Complete Water Solutions’ comprehensive glossary of terms.

AAAtomic Absorption Spectroscopy
AAMI Grade WaterWater meeting quality standards established by the Association for the Advancement of Medical Instrumentation and used mainly for hemodialysis systems
ABSAlkylbenzene Sulfonate.
Absolute Filter RatingFilter rating meaning that 99.9% of the particles larger than a specified micron rating will be trapped on or within the filter. Standard test procedures, are listed in the ANSI/NSF standards for particulate and cysts reduction by drinking water treatment units, should be used to determine and substantiate absolute filter ratings.
Absolute pressureThe pressure above a perfect vacuum. It is expressed as psia (pounds per square inch absolute).
Absorbed DoseThe amount of a chemical that enters the body of exposed organism.
AbsorptionThe process of one substance actually penetrating into the structure of another substance. This is different from adsorption in which one substance adheres to the surface of another.
Absorption FactorThe fraction of a chemical making contact with an organism that is absorbed by the organism.
Acceptable Daily Intake (ADI)Estimate of the largest amount of chemical to which a person can be exposed on a daily basis that is not anticipated to result in adverse effects.
Accessible EquipmentWater treatment equipment that when installed and operating is exposable and available for proper and thorough cleaning and inspection using only simple tools such as a screwdriver, pliers or an open-end wrench. Equipment which is easily available for cleaning and inspection without having to use any tools at all is often referred to as readily accessible equipment
Accumulation TankA vessel or tank which received and stores product water for use on demand.
Accumulation TestA pressure test used to ensure that the safety valve has sufficient relieving capacity to vent all of the excess steam that the boiler can produce.
AccuracyHow closely an instrument measures the true or actual value of the process variable being measure or sensed.
AcidA substance which releases hydrogen ions when dissolved in water. Most acids will dissolve the common metals and will react with a base to form a neutral salt and water. An acid is the opposite of an alkali, has a pH rating lower than 7.0, will turn litmus paper red, and has a sour taste.
Acid DewpointThe temperature at which acidic vapors begin to condense out of the flue gases.
Acid Mine DrainageDrainage of water from areas that have been mined for coal or other mineral ores; the water has low pH, sometimes less than 2.0 (is acid), because of its contact with sulfur-bearing material; acid drainage is harmful because it often kills aquatic organisms.
Acid RainPrecipitation which has been rendered (made) acidic by airborne pollutants.
AcidicThe condition of water or soil which contains a sufficient amount of acid substances to lower the pH below 7.0.
AcidificationThe addition of an acid (usually nitric or sulfuric) to a sample to lower the pH to below 2.0. The purpose of acidification is to "fix" a water sample to it won't change until it is analyzed. The sample is then said to be "acidified"
AcidityThe quantitative capacity of a water or solution to neutralize an alkali. Acidity is usually measured by titration with a standard solution of sodium hydroxide and expressed in ppm or mg/L of calcium carbonate equivalent.
Acre-FootThe volume of water which would cover an area of one acre to a depth of one foot. It is equal to 43,560 cubic feet or 325,851 gallons.
AcrylicIon exchange resin base made of polyacrylate rather than the more common polystyrene.
Action LevelThe concentration of lead or copper in the water specified at Code of Federal Regulations 141.80(C) Which determines, in some cases, the treatment requirements contained in sub-part I of this code that a water system is required to complete.
Activated AluminaA medium made by treating aluminum ore so that it becomes porous and highly absorptive. Activated alumina will remove several contaminants including fluoride, arsenic, and selenium. When exhausted, activated alumina requires a two-step regeneration process, consisting of applications of sodium hydroxide (caustic) in the first step, and followed by neutralization with sulfuric acid in the second step.
Activated CarbonA water treatment medium, found in block, granulated or powdered form, which is produced by heating carbonaceous substances (bituminous coal or cellulose- based substances such as wood or coconut shell) to 700°C or less in the absence of air to form a carbonized char, and then activating (oxidizing) at 800°C to 1000°C with oxidizing gases such as steam and carbon dioxide (oxygen is never used as the oxidizing gas because its reaction with the carbon surface is too rapid and violent) to form pores, thus creating a highly porous absorbent material. Activated carbon is commonly used for chlorination and for reducing trace and soluble materials such as organic chemicals and radon from water.
Activated Carbon Block FilterActivated carbon block is a blend of fine activated carbon (e.g., 80 x 325 mesh activated carbon), water, and a suitable binder (such as polyethylene or a similar material) that is mixed and molded and hardened or extruded to a cartridge filter of any size and shape. Sometimes specialized media are added along with activated carbon to provide customized performances for specific contaminants. The binder is particularly designed and chosen to hold the carbon and other media in a fixed solid matrix, yet, not to plug up the pores of the activated carbon. Even though the binder does occlude a portion of the adsorption sites, the finer mesh gives activated carbon block filters faster adsorption kinetics and generally two to four times greater adsorption capacity than equivalent volumes of loose granular activated carbon. Activated carbon block filters typically have a 0.5 to one micron filtration capability, making it also helpful for particulate filtration, insoluble lead reduction, and demonstrating, in some cases, removal of Giardia and Cryptosporidium.
Activated SilicaA negatively - charges colloidal substance generally formed by combining a dilute sodium silicate solution with a dilute acidic solutions (or other activant). Generally used as a coagulant aid.
Active TransportA energy - expending mechanism by which a cell moves a chemical across the cell membrane from a point of lower concentration to a point of higher concentration, against the diffusion gradient.
Actuator A device that receives a control signal from a controller and converts the signal into a proportional movement of the valve.
AcuteOccurring over a short period of time; used to describe brief exposures and effects which appear promptly after exposure.
Acute Exposure A single exposure to a toxic substance which results in severe biological harm or death. Acute exposures are usually characterized as lasting no longer than a day.
Acute ToxicityThe ability of a substance to cause poisonous effects resulting in severe biological harm or death soon after a single exposure or dose. Also, any severe poisonous effect resulting from a single short-term exposure to a toxic substance.
Additive Effect Combined effect of two or more chemicals equal to the sum of their individual effects.
AdsorbateThe liquid, gas, or solid substance which is adsorbed as molecules, atoms, or Ions.
AdsorbentA water treatment medium, usually solid, capable of the adsorption of liquids, gases, and/or suspended matter. Activated alumina and activated carbon are common adsorbents used in water processing.
AdsorptionAdsorption is the binding of a molecule to a surface (solid or liquid) by non-specific physical forces. For example, the removal of free chlorine and chloramines by activated carbon is through the mechanism of adsorption.
AerationThe process whereby water is brought into intimate contact with air by spraying or cascading, or air is brought into intimate contact with water by an air aspirator or by bubbling compressed air through the body of water. Both pressure (Closed) aerators and open (Gravity) Aerators are used. Closed aeration is used chiefly for oxidation; open aeration for degassing.
AerobicAn action or process conducted in the presence of air, such as aerobic digestion of organic matter by bacteria.
Aesthetic ContaminantsCharacteristics of water which affect its taste, order, color, and appearance (and may affect the objects touched by the water) but which do not in themselves have any adverse health effects in otherwise potable water. Suggested Maximum Contaminant Level (MCLs) for various aesthetic contaminants in drinking water are part of the National Secondary Drinking Water Regulations issued by the USEPA. These aesthetic standards are advisory only, not enforceable by the USEPA.
After-treatment The water treatment processes that occur during or after steam generation.
Age TankTank used to store a chemical solution of known concentration for feed to a chemical feeder. Also called a day tank.
AgglomerationThe collection or coalescence of dispersed suspended matter into larger masses or flocs which can settle and be filtered from water.
AggregateA mass or cluster of soil particles, often having a characteristic shape.
AgrochemicalSynthetic chemicals (Pesticides and Fertilizers) used in agricultural production.
Air BindingA situation where air enters the filter media. Air is harmful to both the filtration and backwash process. Air can prevent the passage of water during the filtration process and can cause the loss of filter media during the backwash process.
Air CheckA device which allows water, but not air, to pass through it. An air check is a typical component of a treatment system using a regenerant eductor.
Air DryerA device used to dry out(desiccate) air by removing the water vapor. An air dryer may be used in ozone generation, for example, to produce higher concentration of ozone and lessen the production of corrosive nitrous oxides.
Air GapA clear vertical space between the end of the water treatment device's drainline and the flood level rim of a receptacle which holds water. An air gap is used to prevent cross connection between the water treatment device and a possible source of waste water thereby preventing a reverse flow of water from the sewer into the water supply system. Without an air gap, such reverse flow could occur due to an increase in the pressure in the sewer system or the creation of a negative pressure in the water supply line. Local plumbing codes indicate how wide the air gap needs to be.
Air PaddingPumping dry air into a container to assist with the withdrawal of a liquid or to force a liquefied gas such as chlorine out of a container.
Air Pollutant An airborne substance that produces an adverse effect on humans, animals, vegetation, or materials.
Air StrippingA technique of aeration for the removal of dissolved gases and volatile substances, often pesticides or hydrocarbon products in water supplies. Large volumes of air are bubbled through the water to remove (strip out) the dissolved gases and volatile substances. The equipment used is a tall, open column with baffling or rock-like materials with air forced upward through a descending sprayed stream or water to be treated. SEE ALSO Packed Tower Aeration.
Air-To-Fuel Ratio The ratio of combustion air to fuel. Though not typically expressed as a ratio, it is a reference to the need for proper balance between the relative amounts of combustion air and fuel being delivered to the furnace at any given firing rate.
Alarm ContactA Switch that operates when some preset low, high, or abnormal conditions exists.
AlcoholA class of organic compounds containing one or more hydroxyl groups.
AlgaeA group of single-celled plants which includes both sea water and fresh water varieties.
Algal BloomSudden, massive growths of microscopic and macroscopic plant life, such as green or blue-green algae, which develop in lakes and reservoirs.
AlgicideAny substance or chemical specifically formulated to kill or control algae.
AliphaticA type of organic compound in which the characteristic chemical groups are linked to a straight or branched carbon chain, as opposed to a carbon ring structure. In complex structures, the chains may also be cross-linked. SEE ALSO Aromatic or Heterocyclic.
Aliphatic Hydroxy AcidsOrganic acids with carbon atoms arranged in branched or unbranched open chains rather than in rings.
AliquotPortion of a sample.
AlkaliA substance which creates a bitter taste and a slippery feel when dissolved in water and will turn litmus paper blue. An Alkali has a pH greater than seven and is the opposite of an acid. Highly alkaline waters tend to cause drying of the skin. ALSO SEE Alkalinity and Base
AlkalineThe condition of water or soil which contains a sufficient amount of alkali substances to raise the pH above 7.0.
AlkalinityA measurement of the quantity of chemicals present in water, which can neutralize acids. These include carbon dioxide, bicarbonate, carbonate and hydroxides.
Alkalinity TestThere are 3 different tests used for testing alkalinity. They are usually done in this order. #1 The pH alkalinity test will indicate the presence or absence of hydroxide alkalinity. A pH of 8.3 or above indicates the presence of hydroxide alkalinity. #2 The phenolphthalein test measure "P Alkalinity" Which is made up of all hydroxide alkalinity plus 1/2 of the carbon alkalinity. P alkalinity is that portion of alkalinity above pH 8.3. Phenolphthalein in water changes color from pink about pH 8.3 to clear at pH 8.3. #3 The Methyl Orange Test measures the "M Alkalinity" which is the remaining 1/2 of the carbonate alkalinity plus all of the bicarbonate alkalinity. The methyl orange endpoint is pH 4.5; no alkalinity exists in water below pH 4.5.
Alkylaryl SulfonateA generic term covering a wide range of anionic surfactants and detergent processing aids.
Alkylbenzene SulfonateA major class of alkylaryl surfactants used in detergents: usually sodium salt.
AllotropeOne of several possible forms of a substance.
AlluvialRelating to mud and/or sand deposited by flowing water.
Alpha DecayA type of radioactivity where the nucleus of an atomic species changes or disintegrates via an energetic helium ion being ejected.
Alternating Current (AC) An electric current that reverses its direction at regular intervals.
Alternating SystemA dual automatic softener system functioning with one unit in service and one on standby. When a predetermined gallonage of softened water has passed or when a monitor detects hard water breakthrough, the idle or standby unit automatically goes into service. The spent unit then regenerates and becomes the idea / Standby unit.
AlumThe common name for aluminum sulfate, which is often used as a coagulant in water treatment.
Alumino SilicateSEE Gel Zeolite.
Aluminum SilicateSEE Pumicite.
AmbientEnvironmental or surrounding conditions.
Ambient TemperatureTemperature of the surrounding air.
AmineA chemical that prevents corrosion in a condensate and steam piping.
AmmoniaAn alkaline gas composed of nitrogen and hydrogen.
AmmoniumThe ionic form of ammonia nitrogen, that is usable by plants. ALSO SEE Ammonia.
AmoebaA single-celled protozoan that is widely found in fresh and salt water.
AmperageThe strength of an electric current measured in amperes. The amount of electric current flow, similar to the flow of water in gallons per minute.
AmpereThe unit used to measure current strength.
AmperometricBased on the electric current that flows between two electrodes in a solution.
Amperometric TitrationA means of measuring concentrations of certain substances in water, based on the electric current that flows during a chemical reaction. ALSO SEE Titration
AmphotericA substance, such as aluminum, capable of acting as either an acid or base.
AnaerobicA condition in which there is no air or no available free oxygen.
Anaerobic OrganismAn organism that can thrive in the absence of oxygen. Such as bacteria in a septic tank.
AnalogThe readout of an instrument by a pointer, against a dial or scale.
Analog Signal A continuous signal used in the ongoing control of a continuous process. For example analog signals are used to continuously control the liquid level in a tank, the temperature of material flowing from a heat exchanger etc.
AnalyzerA device which conducts periodic or continuous measurement of some factor such as chlorine, fluoride, or turbidity.
Animal StudiesInvestigations using animals as surrogates for humans on the expectation that results in animals are pertinent to humans.
AnionA negatively charged ion.
Anion ExchangeAn ion exchange process in which anions in solution are exchange for other anions from an ion exchanger. SEE ALSO Ion Exchange.
Anion MembraneSEE Ion Exchange Membrane.
Anionic PolymerA polymer having negatively charged groups of ions; often used as a filter aid and for dewatering sludges.
Annular SpaceA Ring-Shaped space located between two circular objects, such as two pipes.
AnnunciatorAn audible alarm that is created electrically or electronically.
AnodeThe positive pole of an electrolytic system; also the metal which goes into solution in a galvanic cell.
AntagonismInterference or inhibition of the effect of one chemical by the action of another chemical.
Anthracite CoalA geologically older coal that contains a high percentage of fixed carbon and a low percentage of volatiles. Anthracite is also known as hard coal.
AntibioticA Substance produced by certain microorganisms or man-made synthetically, that in dilute solutions, can kill or prevent the growth of microorganisms.
AntiparticleAny of several species of subatomic particles that are identical in mass to ordinary particles, but opposite in electrical charge or in magnetic moment.
AntisepticAnti, against + Sepsis, decay. Preventing or inhibiting the growth and multiplication of microorganisms, especially pathogenic microorganisms, without necessarily destroying them.
AOPAdvanced Oxidation Process.
AppropriativeWater rights to or ownership of a water supply which is acquired for the beneficial use of water by following a specific legal procedure.
AppurtenanceMachinery, appliances, structures, and other parts of the main structure necessary to allow it to operate as intended, but not considered part of the main structure.
AquaticPlants or animal life living in, growing in or adapted to water.
AqueousSomething made up of, similar to, or containing water; watery.
AquiferA natural water-bearing geological formation, which is found below the surface of the earth.
AragoniteA form of calcium carbonate that appears in pearls.
Arithmetic MeanAn average value of data set calculated by determining the sum of all the numbers in the data set and dividing by the number of data values within the set.
AromaticA type of organic compound in which the characteristic chemical groups are linked to a particular type of six- member hexagonal carbon ring which contains three double bonds, typified by benzene. Such rings have peculiar stability and chemical character, and are present in the rather reactive and highly versatile compounds derived from petroleum and cool tar.
ArtesianWater held under pressure in porous rock or soil confined by impermeable geologic formations. An artesian well is free- flowing. ALSO SEE Confined Aquifer.
AsepticA, not + Sepsis, decay. 1. Free or freed from pathogenic organisms and their toxins. 2. A sterile condition, free from germs, infection and any form of life. SEE ALSO Antiseptic, aseptic procedure, disinfect, sanitize, sterilize
Aseptic ProcedureA method used to prevent microbial contamination; equipment and tools are cleaned and sanitized, disinfected, or sterilized.
Ash Fusion TemperatureThe temperature at which ash begins to become molten.
Ash HopperLarge receptacle used to store ashes until they can be disposed of.
ASMECode written by ASME International (American Society of Mechanical Engineers) that governs and controls the types of material, methods of construction and procedures used in the installation of boilers.
AspiratorA device which creates movement of air, liquids, and granular substances by suction.
AssayA test for a particular chemical or effect.
ASTM Grade WaterSEE Reagent Grade Water.
"A" Style Watertube BoilerA watertube boiler design with a top steam and water drum and two smaller bottom mud drums.
AsymmetricNot similar in size, shape, form, or arrangement of parts on the opposite sides of a line, point or plane.
Atmospheric PressureThe force exerted by the weight of the atmosphere bearing on the Earth's surface.
AtomThe smallest possible component of an element. An atom is comprised of a nucleus and one or more electrons which revolve around the nucleus.
Atomic Absorption Spectroscopy (AA) A spectroscopy Chemical analytical technique used for determining the metal elements in water by measuring the well defined characteristic light wave lengths absorbed by each respective element when the element has been thermally excited into an atomic vapor.
AtomizationThe process of breaking a liquid fuel stream into a mist of tiny droplets.
AttritionThe gradual lessening of the capacity or effectiveness of a medium. This may occur due to friction, sacrificial properties of the medium, chemical attack on the medium, or contaminant saturation of the medium.
Automatic Water SoftenerA water softener that is equipped with a clock timer which automatically initiates the backwash and/or regeneration process at certain preset intervals of time. All operations, including bypass of treated or untreated water, backwashing, brining, rinsing, and returning the unit to service are performed automatically.
Autotrophicauto, self + Trophe, nourishment. Capable of obtaining food or nourishment from simple raw materials. ALSO SEE Heterotrophic.
AutotrophsSEE Autotrophic
Available ChlorineA measure of the amount of chlorine available in Chlorinated line, hypochlorite compounds, and other materials that are used as a source of chlorine when compared with that of elemental chlorine.
Available ExpansionThe vertical distance from the sand surface to the underside of a trough in a sand filter. Also called Freeboard.
AverageSEE Arithmetic Mean
Avogadro's NumberThe number of molecules in a gram- molecular weight or the number of atoms in a gram-atomic weight of any substance.
Axial FlowSEE Longitudinal Flow.
Axial to ImpellerThe direction in which material being pumped flows around the impeller or flow parallel to the impeller shaft.
Axis of ImpellerAn imaginary line running along the center of a shaft.
BackflowThe flow of water in a pipe or line in a direction opposite to the normal flow. Backflow is a problem if there is a back siphonage or back pressure causing reverse flow from a cross connection. ALL SEE Back Siphonage and Cross Connection.
Backflow PreventerA device or system installed in a water line to stop backflow from a nonportable source. ALL SEE Air Gap.
Background LevelIn contaminant monitoring, the average presence of a substance in the environment, originally referring to naturally occurring phenomena.
Back PressurePressure which creates resistance against a flow of water.
Back Siphonage A form of backflow which occurs due to negative pressure. SEE ALSO Backflow, Vacuum Breaker.
BackwashThe up flow or countercurrent flow of water through a filter medium or ion exchange medium for the purpose of thoroughly expanding the media bed to remove foreign particulate matter accumulated during the service cycle and to flush it to the drain.
Back-SeatingThe situation where a slow-opening valve such as a gate or globe valve is fully opened until it stops.
BacteriaBacteria are single cell micro-organisms capable of replicating on their own. They can be divided into two broad categories, aerobic (requiring oxygen) and anaerobic (not requiring oxygen). Bacteria can live in a very broad range of habitats. Some, for example pseudomonads, can thrive in environments containing a very low level of nutrients. These bacteria are frequently slime producers and are a major problem in water treatment systems. Other bacteria, which adhere to surfaces, secrete a gelatinous material that serves to protect the bacteria from chemical disinfectants. This combination of bacteria and their protective coating is sometimes referred to as biofilm. The concentration of bacteria in water is commonly given in terms of colony forming units (cfu) per mL. A colony forming unit is viable bacterium able to replicate to form a whole colony when incubated in each environment.
Bacterial LyonSEE Iron Bacteria.
Bactericide Any substance or agent which kills bacteria, both disease causing and non disease causing. Spores and non bacterial microorganisms are not necessarily killed by bacteria.
BacteriostaticHaving the ability to inhibit the growth of bacteria without destroying the bacteria.
Badge PlateA data plate attached to a boiler.
BaffleA metal or refractory-covered panel that directs the flow of gases of combustion for maximum boiler heating surface contact.
BagA protruding bubble or bulge in the steel plate of a boiler.
BailerA 10 to 20 foot long pipe equipped with a valve at the lower end.
Baking SodaSEE Sodium Bicarbonate
Balanced FlowA flow pattern which is controlled to achieve the flow specified for that water treatment system.
BallastThe power supply to activate and regulate voltage in an ultraviolet lamp.
Ball Check ValveAn automatic self-closing gauge glass valve.
Ball Valve A quick-acting, two position shutoff valve.
Banking A FireThe process of greatly slowing the burning of coal or some other solid fuel.
BarA unit of pressure. One bar equals 14.5 Pounds Per Square Inch (PSI) or about 0.987 Standard Atmospheres.
Barium FoulingIn ion exchange deionization, a condition where the cation exchange resin becomes coated with a very insoluble coating of barium sulfate. This occurs in the decationization unit when regenerated with sulfuric acid, where a barium bearing water is being processed. Generally, the remedy must be to replace the cation resin and install up steam water softening to remove the barium prior to the deionization treatment.
Barometric DamperA free swinging adjustable balanced damper used on smaller boilers to automatically limit the amount of air pulled through the combustion chamber.
BaseAn alkali which releases hydroxyl ions when dissolved in water and causes pH of the water to rise. SEE ALSO Alkali and Alkalinity.
Base ExchangeSEE Cation Exchange.
Base MetalA metal (Such as iron) which reacts with dilute hydrochloric acid to form hydrogen. SEE ALSO Noble Metal.
Batch TreatmentA method in which a fixed quantity of water is processed through a single treatment device in a single vessel.
BatteryA group of boilers that feed steam into the same steam header.
BaumeAn arbitrary scale of specific gravities used in the graduation of hydrometers.
Bay SaltA relatively coarse salt made from seawater.
BeadSEE Resin Bead
Bead CountA method of evaluating the physical condition of the resin in a bed by determining the percent of whole, cracker, or broken beads in a wet sample of the resin.
Beaver FeverSEE Giardia Iamblia
BecquerelThe SI unit of radioactivity equal to one nuclear disintegration per second.
BedThe mass or volume of ion exchange resin or other media through which the water passes in the process of water treatment.
Bed DepthThe height of the resin or other media in a bed, usually expressed in inches or centimeters.
Bed ExpansionThe effect produced during backwashing when the resin or other medium becomes separated and rises in the tank or column.
Bed VolumeA term used as a measurement of a volume of incoming in gallons or liters equal to the volume of ion exchange or filter media product in a tank, including voids.
BellowsA flexible device that expands and contracts with changes in pressure.
Bench Scale Bench scale testing is usually conducted in the lab, but is a simulated test in which conditions are approximate to those with which the item will be used.
Bent-Tube Watertube BoilerA boiler design in which the tubes are bent to some degree.
Best Available Technology (BAT)The best technology treatment techniques, or other means which the administrator finds, after examination for efficacy under field conditions and not solely under laboratory conditions, that are available.
Best Management Practices (BMPs)Structural, nonstructural and managerial techniques that are recognized to be the most effective and practical means to control nonpoint source pollutants yet are compatible with the productive use of the resource to which they are applied.
Beta-Minus DecayA type of radioactivity where the nucleus of an atomic species changes or disintegrates via negatron emission - an energetic negative electron being emitted.
Beta-Plus DecayA type of radioactivity where the nucleus of an atomic species changes or disintegrates via an energetic positron being created and emitted, along with a neutrino.
Bended Fuel Oil A mixture of distillate oils and residual oils that may contain some crude oil.
BiasAn inadequacy in experimental design that leads to results or conclusions not representative of the population under study.
Bicarbonate AlkalinityThe alkalinity of a water due to the presence of bicarbonate ions.
Bicarbonate HardnessThe hardness of a water due to the presence of a calcium and magnesium bicarbonates, usually the major component of carbonate hardness or total hardness. Also called carbonate hardness.
Bicarbonate of SodaA common name, along with baking soda, for sodium bicarbonate.
BioaccumulationThe retention and concentration of a substance by an organism.
BioassayTest which determines the effect of chemical on a living organism.
Biochemical Oxygen Demand (BOD)The amount of oxygen required in the oxidation of organic matter by biological action under specific standard test conditions. Widely used to measure the amount of organic pollution in waste water and streams.
BiocideA chemical which can kill or inhibit the growth of living organisms such as bacteria, fungi, mold and slimes.
BioconcentrationThe accumulation of a chemical in tissues of an organism to levels that are greater than the level in the medium in which the organism resides. ALSO SEE Bioaccumulation
BiodegradableSubject to degradation into simpler substances by biological action.
BiodegradationDecomposition of a substance into more elementary compounds by the action of microorganisms such as bacteria.
BiofilmAn accumulation of sessile microbial growth imbedded in a film of adhesive polymer and attached on the surface of a support material, such as the interior surface of water pipe or water storage vessels. Bacteria within the film may be protected from the action of disinfectants and sanitizers. SEE ALSO sessile.
BiogasSEE Methane
Biological GrowthThe activity and growth of any and all living organisms.
Biologically Activated CarbonActivated carbon which maintains active microbiological growth to aid in the degradation and reduction of organics that have been adsorbed on the surface and in the pores of activated carbon.
BioremediationA process of adding nutrients to groundwater to speed up the natural process in which bacteria breakdown gasoline into harmless compounds.
BiostatAn agent similar to a bacteriostat but prevents the growth of all living organisms. SEE ALSO Bacteriostatic.
BiotaAn overall term for all living organisms in an ecosystem.
BiotransformationConversion of a substance into other compounds by organisms.
BIRMThe trade name for a manganese dioxide- coated volcanic aluminum silicate used as an oxidizing catalyst filter for iron and manganese reduction.
BitternsSEE Mother Liquor
Bituminous CoalA geologically younger coal that contains a high percentage of volatiles and a low percentage of fixed carbon. Bituminous coal is also known as soft coal.
BivalentHaving a valence of two. Also called Divalent.
Black WaterLiquid and solid human body waste and the carriage water generated through toilet usage.
BlankA bottle containing only dilution water or distilled water.
BleachA strong oxidizing agent and disinfectant formulated to break down organic matter and destroy organisms. Commonly refers to a 5.25% nominal solution of sodium hypochlorite which is equivalent to 3% to 5% available commercially in concentrations of between 5% and 15% available chlorine.
Blind SpotPlaces in the filter medium or membrane where no filtration takes place.
Blinding The reduction or shutting off of flow due to filter medium or membrane fouling. SEE ALSO Fouling.
Blister A lamination of steel plate or tube surfaces or where the steel plate splits into layers.
Block CarbonSEE Activated Carbon Block Filter.
Blowback The drop in pressure in the boiler that occurs after the safety valve has opened.
Blowby1. The technique sometimes used for recycling concentrate back to the feed. 2. Contaminate leakage through or by the water treatment device.
Blowdown The amount of pressure in a pressure vessel that must be reduced before a safety valve reseats. Removal of impurities from the boiler water by draining some of the water.
Blue-Green AlgaeSEE Cyanobacteria.
BODBiochemical Oxygen Demand.
Boiler Heating SurfaceAny part of the boiler metal that has hot gases of combustion on one side and water on the other.
Boiler Horsepower (BHP)The energy required for the evaporation of 34.5 lb of water at 212°F into steam at atmospheric pressure and at 212°F in 1 hr.
Boiler Load The amount of steam being produced by a boiler.
Boiler MasterA controller that determines the appropriate quantities of fuel and air that need to be provided to a boiler's combustion equipment in order to produce the required quantity of steam.
Boilers In BatteryTwo or more boilers connected to a common steam header.
Boiler Thermal EfficiencyThe percentage of the heat liberated that is transferred into the boiler water.
Boiler VentA section of steel pipe about 1/2" to 1" ID connected to the top of a boiler. The boiler vent allows air to be removed from the boiler when filling and when heating. It also allows air to be drawn in when steam in the boiler collapses into vacuum conditions during cool-down, or when draining the boiler.
Boiler WaterA representative sample of the water or steam condensate circulating in a boiler system, taken after the generated steam has been separated and before the incoming feedwater or any added chemical has become mixed with the sample to change its composition.
Boil-Out ProcedureThe process of removing oily residues from a boiler by adding chemicals to the boiler water and boiling the mixture for a period of time.
Bone CharA black pigment substance, with a carbon content of about 10%, made by carbonizing animal bones. Boone char is used for decolorizing sugar and water treatment. It has been used as a selective anion exchanger for fluoride and arsenic reduction.
BonnetThe cover on a gate valve.
Bored WellA shallow (10 to 100 Feet or 3 to 30 Meters) large diameter well (8 to 36 inches or 20 to 90 CM) constructed by hand operated or power driven augers.
Bottled Artesian WaterBottled water from a well tapping a confined aquifer in which the water level stands above the water table.
Bottled Distilled WaterBottled water which has been produced by a process of distillation and meets the definition of purified water in the most recent edition of the United States Pharmacopeia. SEE ALSO Bottled Water and Distilled Water.
Bottled Fluoridated WaterBottled water containing Fluoride.
Bottled Mineral WaterBottled water coming from an approved source tapped at one or more boreholes or natural springs, originating from a geologically and physically protected underground water source.
Bottled Natural WaterBottled spring, mineral, artesian or well water which is deprived from an underground formation, and is not derived from a municipal system or public water supply.
Bottled Spring WaterBottled water derived from an underground formation from which water flows naturally to the surface of the Earth or is pumped through a borehole from a spring source.
Bottled WaterWater that is placed in a sealed container or package, and is offered for sale for human consumption or other consumers uses.
Bottled Water PlantAny place or establishment in which bottled water is prepared for sale.
Bottom BlowdownThe process of periodically draining part of the boiler water to remove heavy sludge that settles to the bottom of the boiler.
Bourdon TubeThe tube inside a mechanical pressure gauge. It is bronze or stainless steel tube bent into a question mark shape and flattened into an elliptical shape.
Brackish WaterWater containing dissolved solids in the range of > 1,000 to <15,000 PPM.
Brake Horsepower1. The horsepower required at the top or end of a pump shaft. 2. The energy provided by a motor or other power source.
Branch LineThe piping that takes steam from the steam mains to individual pieces of steam using equipment.
BrassA metal alloy of copper, zinc and usually some lead.
Breakpoint ChlorinationA Chlorination procedure in which the chlorine is added until the chlorine demand is satisfied and a chlorine residual occurs.
BreakthroughThe first appearance in the product water of an amount of the contaminant which exceeds the design performance criteria.
BreechingThe ductwork that carries cooled flue gases from the exit of the boiler to the stack.
Bridge WallA firebrick wall built across a boiler furnace.
Bridging1. Bridging occurs in water softening when salt sticks together to form one large solid mass of pellets, or by the salt caking in a dry-salt brine tank which causes failure of the liquid or brine beneath the dry salt to become saturated. 2. The ability of particles to form a crustlike film over void spaces within a filter medium or membrane. SEE ALSO mushing.
BrineA Solution of salt and water.
Brine CollectorA device used to gather and retrieve brine from a brine tank or ion exchange bed.
Brine DrawUsually means the process of drawing a brine solution into a cation or anion exchange water treatment device during regeneration.
Brine Ejector (Eductor)A device used to draw brine from a brine tank and force it into a cation and/or anion water treatment device.
Brine Tank GridA perforated platform in the bottom section of a brine tank of home water softeners which creates a zone where water can come in contact with the lower side of the dry salt stored above. As the water reaches up to the salt layer, it creates the brine makeup for regeneration.
BrinellingTiny indentations high on the shoulder of a water pump's bearing race or bearing. A type of bearing failure.
British Thermal Unit (BTU)The amount of heat necessary to raise the temperature of 1 Pound of water by 1°F.
BromineA nonmetallic usually univalent or pentavalent element that lies between chlorine and iodine in the halogen group on of the periodic table.
Brownian MovementThe random movement of microscopic particles suspended in a fluid.
Bubbler ControlA set of components that use a small flow of compressed air or another gas to detect the level of liquid in a vessel such as a storage tank.
Bubble SizeThe average diameter of the gas bubbles discharged from a a diffuser at the bottom of the contractor in an ozone or aeration system.
BuckstayA metal brace used to attach a wall to steel framework that supports the wall.
BufferA Chemical substance which stabilizes pH values in solutions.
Buffer CapacityA measure of the capacity of a solution or liquid to neutralize acids or bases. This is a measure of the capacity of water for offering a resistance to chance in pH.
BuilderA material that upgrades or protects the cleaning efficiency of the surfactant.
Bunker OilOne of the heavy oils formed as crude oil is stabilized after the lighter components have been distilled off.
Burnt LimeSEE Lime.
Butterfly Valvea valve that consists of a circular disc that is rotated by the valve stem so that the disc is parallel to the flow through the valve, perpendicular to the flow or somewhere in between.
Bypass DamperControls the air temperature in air heaters to prevent corrosion.
Bypass LineA pipeline that passes around a control, heater or steam trap. Used so that a plant can operate while equipment is serviced or repaired.
CACellulose Acetate.
CAGCarcinogen Assessment Group.
CaissonA Structure or chamber in water well construction which is usually sunk or lowered by digging from the inside. Used to gain access to the bottom of a stream or other body of water.
Calcite1. Calcium Carbonate. 2. A trade name for finely ground grades of marble or limestone, very high in calcium carbonate, which are used to raise the pH reading or low pH water or to filter out sediment.
CalciumOne of the principal elements making up the earth's crust. When dissolved it makes water hard.
Calcium CarbonateChemical compound found in nature as calcite and in plants ashes, bones and many shells.
Calcium Carbonate EquivalentThe weight or concentration of calcium carbonate that would have the same number of ionic charges to a certain amount of another material.
Calcium ChlorideA soluble salt, some uses of which are similar to those of sodium chloride. Since its most striking property is its ability to draw moisture from the air and so dissolve itself, it is often used as an air dryer and as a de-icing salt.
Calcium HydrateSEE Hydrated Lime.
Calcium HydroxideSEE Hydrated Lime.
Calcium HypochloriteA chemical compound used as a bleach and source of chlorine in water treatment.
Calcium OxideSEE Lime.
Calcium Sulphate SaturationThe point beyond which any further addition of calcium sulfate to a given solution with case precipitation.
CalibrateAdjusting an instrument to optimize its accuracy.
CalibrationA procedure which checks or adjusts an instrument's accuracy by comparison with a standard or reference.
CalorieThe amount of heat necessary to raise the temperature of 1 gram of water by 1°c.
CalorimeterA laboratory instrument used to measure the heat content of a substance, such as a sample of a fuel to be used for a boiler.
CalyxSEE Lime.
CAP Grade WaterWater which meets standards established by the College of American Pathologists. The standards cover 3 types of lab grade water, clinical, cell or tissue and Cultural.
CapacityThe maximum performance of a devise i.e., condensate flow through a steam trap, steam generation of a boiler or liquid delivery by a pump.
Capacity Curve (Ion Exchange)A graph of the ion exchange capacity vs regenerant levels for an ion exchange unit or system.
Capillary ActionA phenomenon in which water or other liquids will rise above the normal liquid level in a tiny tube or capillary due to the attraction of the molecules in the liquid for each other and for the walls of the tube.
Capillary ForcesThe molecular forces which cause the movement of water through very small spaces.
Capillary FringeThe porous material just above the water table which may hold water by capillary in the smaller void spaces.
Capillary TubeA long, small-diameter tube, usually of stainless steel or a copper alloy.
Capital CostsCost of financing construction and equipment.
CarbonAn element which is found in almost all living or formerly living material including plants, proteins, organics and hydrocarbons.
Carbon BlockSEE Activated Carbon Block Filter.
CarbonaceousContaining carbon and derived from organic substances such as coal, coconut shells, and wood.
Carbonaceous ExchangerCation Ion exchangers or limited capacity, prepared by the sulfonation of coal, lignite or peat.
Carbonate AlkalinityAlkalinity due to the presence of the carbonate ion.
Carbonate HardnessThe hardness in water caused by bicarbonates and carbonates of calcium and magnesium.
Carbonated WaterSEE Soda Water.
Carbon Chloroform Extract (CCE)A measure of the organic matter in a water. To get this measurement, the matter adsorbed from the water by activated carbon is extracted from the carbon by using a specific standardized procedure involving chloroform.
Carbon DioxideA naturally - occurring as, present in the atmosphere and formed by the decay of organic matter.
Carboxylic A specific acidic group having a chemical formula that contributes cation exchange ability to some resins.
CarcinogenAny substance which tends to produce cancer in an organism.
CarryoverThe entrainment of small water droplets with steam leaving the boiler.
CartridgeAny removable preformed or prepackaged component containing a filtering medium, ion exchanger, membrane, or other treatment material which fits inside a housing to make up a cartridge filter.
Cartridge FilterA device often used for single faucet water treatment, made up of a housing and a removable cartridge.
CAS Registration NumberA number assigned by the Chemical Abstracts Service to identify a chemical.
Cascading ControlA Control scheme in which one process variable is measured and used to set the setpoint of another controller.
CatalystA substance that changes the speed or yield a chemical reaction without being consumed or chemically changed by the chemical reaction.
Catalyst MediaThose filter media which can cause certain reactions to occur in water treatment, such as activated carbon, calcite, manganese greensand, magnesium oxides, and dissimilar metal alloys.
Catalyst/ Oxidizing FiltersA class of media bed filters which contain manganese treated greensand, zeolites, or pumicites.
Catalytic Activated CarbonActivated carbon with modified surface properties that enhance the functionality of the activated carbon in converting the oxidation state of various elements.
Catalytic Ozone DestructorA type of ozone destruction unit that uses a catalyst to enhance the performance of the off gas treatment system.
CatalyzeTo act as a catalyst, or to speed up a chemical reaction.
CatalyzedTo be acted upon by a catalyst.
CathodeA negative pole of an electrolytic system; An electrode where reduction occurs.
Cathodic ProductionThe sacrificial use of one metal to protect against the surface corrosion of another surface.
CationAn ion that has a positive electrical charge.
Cation ExchangeThe ion exchange process in which cations in solution are exchanged for other cations available from an ion exchange product. Formerly called Base Exchange. SEE ALSO Ion Exchange.
Cation Exchange ResinAn ion exchange material possessing reverse exchange ability for cations. Sulfonated polystyrene copolymer divinylbenzene Exchange resin is used almost exclusively today in ion exchange water softeners.
Cation Exchange Water SoftenerAn equipment unit capable of reducing water hardness by the cation exchange process.
Cation ExchangerSEE Cation Exchange Resin.
Cation MembraneSEE Ion Exchange Membrane.
Cation PolymerA polymer having positively charged groups of ions; often used as a coagulant aid.
Caustic1. Caustic soda or any compound chemically similar to caustic soda. 2. Any substance capable of burning or destroying animal flesh or tissue. The term is usually applied to strong bases.
Caustic EmbrittlementA problem in which boiler metal becomes brittle and weak because of cracks in the crystalline structure of the metal.
Caustic LimSEE Hydrated Lime.
Caustic SodaSEE Sodium Hydroxide.
CavitationThe condition caused when a portion of the water or other liquid entering the eye of a pump impeller flashes into steam bubbles.
CCECarbon Chloroform Extract.
CellulaseAn enzyme which causes the decomposition of cellulose.
Cellulose AcetateA synthetic polymer derived from naturally occurring cellulose and widely used in the fabrication of membranes. The polymers used for water purification membranes may be diacetate, triacetate or blends of these materials.
Cellulose Ion ExchangersCellulose - base products which have been cross linked and then modified with either anion or cation groups capable of selective ion exchange.
Cellulose Triacetate (CTA)SEE Cellulose Acetate.
CentrateThe water leaving a centrifuge after most of the solids have been removed.
Centrifugal PumpA pump in which a rotating impeller throws liquid from its vanes through centrifugal force.
CentrifugeA mechanical device that uses centrifugal or rotation forces to separate solids from liquids.
C FactorA factor or value used to indicate the smoothness of the interior of a pipe.
CFUColony - forming units.
Chain-Grate StokerA stoker in which the grates are composed of thousands of small staggered segments that are interlaced by support bars or rods, forming a heavy chain conveyor.
Challenge WaterWater specifically prepared for testing the performance of water treatment equipment products.
ChannelingThe high and unbalanced flow of water or regenerant through a limited number of passages in a filter or ion exchanger bed, as opposed to an evenly distributed flow through all passages in the bed.
CharcoalAn adsorbent carbon product which has about 1/3 the surface area of activated carbon.
Charged Polysulfone MembraneNormal polysulfone membranes contain physical pores that can pass salts; they are sued in ultra filtration water treatment.
Check ValveA One-way flow valve for fluids.
CharacterizationThe relationship between the amount a valve is open and the amount of flow through the valve.
ChelantA chemical that helps keep the hardness in the water dissolved so that it does not crystallize on heating surfaces.
Chelating AgentA chemical or complex that interacts with an ion, usually a metal, causing the ion to join that chemical or complex by both ordinary and coordinate valence forces.
Chelating Ion ExchangerA special selective resin which will adsorb one metal ion to the exclusion of any other present in a stream of water. SEE ALSO Chelation.
ChelationThe process of forming complex chemical compounds in which certain metal ions are bound into stable ring structures, keeping the ions in solution and eliminating or reducing normal effects of the ions.
Chemical ConcentrationThe amount of a specific chemical found in a solution, i.e. boiler water, condensate etc.
Chemical EnergyEnergy in the fuel that converts to heat energy during the combustion process.
Chemical Feeder (Feed Pump)A system used to introduce and feed, on a proportional basis, a Chemical solution into a stream of water.
Chemical LimeSEE Calcium Oxide; Lime.
Chemical Oxygen Demand (COD)An indirect measure of the amount of oxygen used by inorganic and organic matter in water. The measure is a lab test based on chemical oxidant and, therefore, does not necessarily correlate with biochemical oxygen demand.
Chemical Precipitation SofteningSEE Lime Softening; Lime- Soda Ash Softening.
Chemical StabilityResistance to attack by chemical action.
Chemically Reactive MediaThose granular or bead form materials used in filtration processes which can react chemically with constituents in the water and serve to modify the water quality.
ChemisorptionA process related to adsorption in which atoms or molecules of reacting substances are held to the surface atoms of a catalyst by electrostatic forces having about the same strength as chemical bonds.
ChillerA component designed to remove heat from a gas or liquid.
ChimneyUsed to create draft. Also an outlet to the atmosphere for the gases of combustion.
ChloraminesChemicals used to disinfect municipal water. They are formed by reacting ammonia and free chlorine and may occur naturally when free chlorine combines with ammonia arising from the breakdown of vegetation. Chloramines are strong oxidants that are highly toxic in hemodialysis applications.
Chlorinated HydrocarbonsA group of organic chemicals formed by reacting petroleum derived chemicals with chlorine. Such chemicals include pesticides and herbicides and are frequently potent carcinogens.
Chlorinated Polyvinyl Chloride (CPVC) A rigid, high - Strength thermo- plastic polymer that is practically inert towards water, inorganic reagents, hydrocarbons, and alcohols over a broad temperature range, uses for pipe and pipe fitting.
ChlorinatorA mechanical device specifically designed to feed chlorine gas, pellets or solutions such as hypochlorites into a water supply in proportion to the flow of water.
ChlorinationThe treatment process in which chlorine gas or a chlorine solution is added to water for disinfection and control of microorganisms.
ChlorineA gas widely used in the disinfection of water and as an oxidizing agent for organic matter.
Chlorine, CombinedSEE Combined Available Residual Chlorine.
Chlorine Contact ChamberThe part of the water treatment plant where effluent is disinfected by chlorine.
Chlorine DemandA measure of the amount of chlorine which will be consumed by organic matter and other oxidizable substances in water before a chlorine residual will be found.
Chlorine, FreeSEE Free Available Residual Chlorine.
ChlorophenolicCompounds that are phenolic compounds combined with chlorine.
ChlorophenoxyA class of herbicides that may be found in domestic water supplies and cause adverse health effects.
ChlororganicOrganic compounds combined with chlorine. Associated with life processes such as those of algae in water.
ChromatographyA chemical analytical technique which utilizes a process of separating gases, liquids, or solids from mixtures or solutions by selective adsorption.
ChronicOccurring over a long period of time.
Chronic ExposureLong term, low level exposure to a toxic chemical.
Circle of InfluenceThe circular outer edge of a depression produced in the water table by the pumping of water from a well.
CircuitThe complete path of an electric current.
CisternA Small tank or storage facility used to store water for a home or farm. Often used to store rainwater.
ClarifierA large circular or rectangular tank or basin in which water is held for a period of time, during which the heavier suspended solids settle to the bottom.
ClassThe working pressure rating of a specific pipe for use in water distribution systems which includes allowances for surges.
ClassifierA spinning set of vanes located at the coal and air outlet from the pulverizer that separates very fine coal dust from larger coal particles.
Class of FireThe five classes of fires are Class A, started from wood, paper or other combustible materials containing carbon; Class B, started from oil, grease, or flammable liquids; Class C started from electrical devices; Class D started from combustible metals; and Class K, started from grease in commercial cooking equipment.
ClayA type of naturally occurring hydrated aluminum silicate soil. Natural clay is activated used as a coagulant adsorbent filter aid.
CLBsCyanobacteria - like bodies.
Clear WaterA reservoir for the storage of filtered water of sufficient capacity to prevent the need to vary the filtration rate with variations in demand.
ClinkerA mass of coal and ash that has fused together during burning.
Clinker GrinderLarge set of steel rollers with heavy teeth that grind ash and clinkers to reduce their size before they enter the ash hoppers.
Closed Feedwater HeaterFeedwater heater in which steam and feedwater do not come into direct contact. Steam is in the shell of the heater while water passes through tubes.
Closed Heat ExchangerA heating unit in which the heating medium and the fluid being heated do not mix but are separated by tube walls or other heating surfaces.
Closed ImpellerAn impeller that has shrouds on both sides of the vanes.
Closed SystemA steam system in which the condensate is recovered and returned to the boiler.
CoagulantA chemical which causes dispersed colloidal particles to become destabilized thereby aiding in their removal during municipal water treatment. Aluminum and iron salts are commonly used for this purpose.
Coagulant AidA material which is not a coagulant, but which improves the effectiveness of a coagulant.
CoagulationA practice common in municipal water treatment in which a chemical (coagulant), most commonly alum, is added to water to destabilize colloidal particles by neutralization of their electrical charges. Coagulation is used, together with flocculation, as a process for colloid removal.
Coal BunkerAn overhead bin where large quantities of coal are stored.
CoalescenceThe union of growing together of colloidal particles into a group or larger unit as a result of molecular attraction on the surfaces of the particles.
Coal FeederControls the flow of coal entering the pulverizer
Coal GateUsed to control the depth of coal entering the boiler furnace on chain grate stokers.
Coal RamDistributes coal evenly into the center retort on underfeed stokers and forces the coal up to the top where it is burned.
Coal ScaleMeasures and records the amount of coal fed to stoker-fired or pulverized coal-fired boilers.
Coarse MeshThe large end of the water treatment media and resin bed size spectrum.
CODChemical Oxygen Demand.
CodeA regulation or law.
Coefficient of expansionThe property of a given material that expresses how much a standard unit of length of the material expands or contracts under a specific change in temperature.
CogenerationThe process of generating electricity and then using the leftover heat from the generating process for heating buildings, providing process heat, or for further electrical generation
CohesionMolecular attraction which holds two particles together.
Coil Watertube BoilerA boiler design in which the tubes are formed into a continuous coil, with the combustion gases passing through the interior of the coil.
CokingThe separation of heavy carbon-based fractions from the oil, resulting in precipitation of solids that may plug the piping.
Cold SterilizationThe use of submicron filtration to screen out bacteria from a water or fluid.
Coliform BacteriaA particular group of bacteria primarily found in human and animal intestines and wastes. These bacteria are widely used as indicator organisms to show the presence of such wastes in water and the possible presence of pathogenic bacteria.
CollectorA device or system designed to collect backwash water from a filter or ion exchange bed. A collector may also be used as an upper distributor to spread the flow of water in down flow column operations.
ColloidUndissolved, submicron-sized suspended particles that are well dispersed in a solution and will not readily settle out on standing.
Color Wheel Comparator TestA relatively simple test used to determine the quantity of iron in the condensate or makeup water.
Color ThrowThe discharge throw of color into the effluent of an ion exchange or filter media system by any component.
Colorimetric MeasurementA means of measuring unknown chemical concentrations in water by measuring a samples color intensity.
Column A vessel, usually a cylindrical and vertical tank, with an inlet at one end and an outlet at the other end, with some means of holding the medium in place so that a stream of water passing through it is processed.
Column of waterWater of some specified depth or height.
Column OperationThe process in which the solution to be treated is passed through a column in either an up flow or down flow pattern.
Combined Available Residual ChlorineThe concentration of residual chlorine which is combined with ammonia and/or organic nitrogen in water as chloramine yet is still available to oxidize organic matter and utilized its bacteria properties. The combined chlorine compounds are more stable then free chlorine forms, but are somewhat slower in reactions.
Combined-cycle BoilerAn electric power generating system that uses both a gas turbine-driven generator and a steam turbine-driven generator.
Combustion Air PreheaterA piece of equipment provided to preheat the combustion air to some degree before the combustion air enters the furnace.
Combustion ChamberThe area of a boiler where the burning of fuel occurs.
Combustion EfficiencyThe percentage of the British Thermal Unit (BTU) content of fuel that is liberated as heat by a boiler's fuel-burning equipment.
CommissioningThe process of inspecting, preparing, and testing each major component of a system prior to operation.
Community Water System (CWS) A Public water system which serves at least 15 service connections used by year round residents or regularly serves at least 25 year round residents.
CompactionThe undesirable physical compression of a reverse osmosis or ultrafiltration membrane that results in reduced flux rates. The phenomenon is accelerated at higher temperatures, pressures, and fouling.
Compensated HardnessA calculated value based upon the total hardness, the magnesium to calcium ration, and the sodium, iron, and manganese concentrations in a water. This value is used to correct for the reduction in hardness removal capacity of a cation exchange water softener, which is caused by the presence of the substances.
Complete CombustionA fire where the fuel is burned with a slight excess of oxygen so that the fuel is completely consumed without forming any smoke, and only a minimal amount of oxygen is left over.
Complete TreatmentIn municipal water treatment, a methods of treating water which consists of the addition of coagulant chemicals, flash mixing, coagulation- flocculation, sedimentation, and filtration. Also called Conventional Filtration.
ComplexationThe inactivation of an ion by addition of a reagent that combines with it and, in effect, prevents it from participating in other reactions. Also called Sequestration.
ComplexesCompounds formed by the union of two or more simple salts.
Compliance CycleThe 9 year Calendar year cycle during which public water systems must monitor for regular drinking water contaminants.
Compliance PeriodAs defined by the USEPA National Primary Drinking Water Regulations a compliance period is a 3 year calendar period within a compliance cycle.
Composite MembraneA semipermeable membrane used in water treatment, consisting of rejecting barrier layer of one chemical composition supported by one or more layers of porous materials with different compositions.
CompoundA substance composed of two or more elements whose composition is constant.
CompressionThe exertion of equal forces from opposite sides of an object that push toward the middle.
ConcentrateIn cross flow filtration, the portion of a feed stream which does not permeate the medium but retains and is increased in the amounts of ions, organics, and suspended particles which are rejected by the medium.
Concentration Polarization1. The ratio of the salt concentration in the membrane boundary layer to the salt concentration in the bulk stream. The most common and serious problem resulting from concentration polarization is the increasing tendency for precipitation of sparingly soluble salts and the deposition of particulate matter on the membrane surface. 2. Used in corrosion studies to indicate a depletion of ions near an electrode. 3. The basis for chemical analysis by polarograph.
Concentrate RecycleA Technique for increasing the amount of product water by recycling a fraction of the concentrate stream back through the membrane or membrane stack.
Concentrate StreamThe stream into which rejected ions and materials are concentrated.
Concentrated SolutionA solution which contains a relatively high quantity of the solute.
Concentration1. The process of increasing the dissolved solids per unit volume of solution, usually bu evaporation of the liquid or separation of the liquid by passage through a semipermeable membrane. 2. The amount of the material dissolved in a unit volume of a solution.
CondensateThe water formed when steam condenses to water.
Condensate PolisherAn ion-exchange water softener similar to a sodium zeolite water softener but with resin that can withstand the high temperatures encountered with condensate.
Condensate PumpUsed to return condensed steam to the open feed water heater.
Condensate receiverA tank or other collection point where condensate is accumulated and saved for reuse.
Condensate Return LineA pipe that carries the condensate and air discharged by the steam traps.
Condensate TankWhere condensed steam (water) is stored before it is delivered back to the open feedwater heater by the condensate pump.
Condensation The process of a vapor reverting to liquid when heat is removed.
Conditioned WaterAny water which has been treated by one or more processes to improve the water's usefulness and/or aesthetic quality by reducing undesirable substances or undesirable conditions.
ConductanceThe quantitative measure of the ability of an electric circuit to allow current flow.
ConductionA method of heat transfer in which heat moves from molecule to molecule.
ConductivityThe ability of an aqueous solution to carry electric current depends on the presence of ions in the solution. Conductivity is a quantitative measure, in which describes this ability. Solutions of inorganic ions are relatively good conductors, whereas solutions of organic molecules are rather poor conductors. Highly purified water is also a poor conductor. Conductivity is expressed in units of Siemen/cm (also known as µs/cm). Conductivity measurements are frequently encountered in monitoring the performance of reverse osmosis equipment. Conductivity is temperature dependent and should be measured with a temperature-compensated meter. The usual reference temperature is 25°C. Conductivity measurements are sometimes used to estimate total dissolved solids (TDS) in water. While convenient, this practice is imprecise.
ConductorA substance, body, device, or wire that readily conducts or carries electrical current.
Cone of DepressionThe depression, roughly conical in shape, produced in the water table by the pumping of water from a well.
Cone of InfluenceThe depression, roughly conical in shape, produced in the water table by the pumping of water from a well.
Confined AquiferAn aquifer in which groundwater is confined under pressure which is significantly greater than atmospheric pressure. SEE ALSO Artesian Aquifer
Confined SpaceA space that has limited or restricted means for entry and exit, has unfavorable natural ventilation such that a dangerous atmosphere could exist inside that does not naturally vent out, and is not intended for continuous employee occupancy.
Confluent GrowthA continuous bacterial growth covering the entire filtration area of a membrane filter, or a portion thereof, in which bacterial colonies are not discrete.
Confounding FactorsVariables other than controlled exposure level which can affect the incidence or degree of parameter being measured.
Connate WaterWater which was deposited, by geological means, simultaneously with the surrounding rock formations and held without flow. Usually this water occurs deep in the earth and is high in minerals due to long contact with the rock.
Consumptive UseWater removed from available supplies without direct return to a water resource system for uses such as manufacturing, agriculture, and food preparation.
Contactor 1. An electrical switch, usually magnetically operated. 2. Equipment used promote contact and mass transfer between treatment materials and the water and other substances to be treated.
Contact Time The time in minutes the water is in contact with an ion exchange medium or filter medium
Contaminant1. Any undesirable physical, chemical, or microbiological substance or matter in a given water source or supply. 2. Any foreign component present in another substance
ContaminationThe introduction of any contaminant into a water source or supply.
Continuous BlowdownThe process of continuously draining water from a boiler to control the quantity of impurities in the remaining water.
Continuous Flow OperationThe process wherein a continuous and steady flow of water is processed for treatment through the media.
Continuous Sample A flow of water from a particular place in a plant to the location where samples are collected for testing.
ControllerA device that takes an input signal, compares the signal to a setpoint, performs a computation and sends an output signal to a final control element.
Control LoopThe collection of control devices and other components necessary for automatic control of a process or sub-process.
Control SystemA system which senses and controls its own operation on a close, continuous basis in what is called proportional control.
Control ValveA valve used to modulate the flow of fluid.
ConvectionA method of heat transfer that occurs as heat is conveyed by a fluid.
Convectional Filtration In municipal water treatment, a method of treating water to remove particulates.
Conventional Filtration TreatmentIn municipal water treatment, as series of processes including coagulation-flocculation, sedimentation, filtration resulting in substantial particulate removal.
Conveyance LossWater lost in conveyance (pipe, channel, conduit, ditch) by leakage or evaporation.
Cooling WaterWater used in the condensation step of a distillation system.
Coordinated Phosphate TreatmentA boiler treatment process using phosphate buffers to avoid the presence of hydroxyl alkalinity.
Core SampleA sample of the medium obtained to represent the entire bed depth when the bed is being analyzed for capacity or usefulness.
CoronaAn electrical discharge effect which causes ionization of oxygen and the formation of ozone.
Corporation StopA water service shutoff valve located at a street water main.
Corresponding PressureThe pressure associated with steam at a given specific temperature.
CorrosionThe loss of metal that occurs in boilers, duct work, etc. as a result of chemical or electrochemical attack.
Corrosion inhibitorA substance that slows the rate of corrosion of metal plumbing materials by water, especially lead and copper materials, by forming a protective film on the interior surface of those materials.
Corrosion - Resistant MaterialA material which resists corrosion after prolonged placement in the environment in which the material was intended to be used.
CorrosivityAn indication of the corrosiveness of water.
CounterflowPrinciple used in heat exchangers where the medium being heated flows in one direction and the medium supplying the heat flows in the opposite direction.
CPVCChlorinated Polyvinyl Chloride.
Crenothrix PolysporaOne of several types of bacteria which utilize iron in their metabolism and are capable of depositing gelatinous ferric hydroxide.
Critical PressureThe pressure at which the density of the water and the density of the steam are the same.
Critical TemperatureThe temperature above which gas cannot be liquefied solely by an increase in pressure
Cross Connection1. A physical connection through which the quality of processed water could be degraded. 2. The condition wherein a nonpotable pipe line is directly piped into a potable water line, resulting in possible back flow or back siphonage and contamination of the drinking water supply.
Cross Contamination1. Contamination which occurs in a mixed bed deionizer unit when anion and cation resins are mixed together after regeneration due to the malfunction of the system. 2. The intermixing of 2 water streams which results in unacceptable water quality for a given purpose.
Crossflow FiltrationA type of filtration that uses the shear force of tangential flow across the membrane surface to keep the particle buildup to a minimum.
Cross - LeakageWater leakage between the demineralized and the concentrate streams in the membrane stack used in the electrodialysis process.
Cross - LimitingThe configuration of boiler combustion controls such that, with an increase or decrease in the firing rate, the combustion conditions never become oxygen deficient.
Cross Linked Polyethylene (XLPE or PEX)Polyethylene that, by cross-link via irradiation of linear polyethylene with an electron beam of gamma radiation, or with a chemical cross linking agent, is made to be a non toxic thermosetting white solid with superior strength and durability, high temperature and pressure resistance, and inertness towards chemical attack and corrosion.
Cross - linkingA comparatively short connection composed of either an element, chemical group, or a compound that bridges between neighboring chains of atoms in a complex chemical molecule.
Cross "T"Used on connections on a water column for inspection of steam and water lines to ensure they are clean and clear.
CryptosporidiosisThe illness produced by infection with Cryptosporidium. Symptoms include fever, headache, nausea, vomiting, anorexia, abdominal cramping, and water diarrhea.
CryptosporidiumA waterborne protozoan that forms oocysts and causes acute gastrointestinal illness in humans.
CT or CTcalcThe product of residual disinfectant concentration in mg/L determined before or at the first customer, and the corresponding disinfectant contact time in minutes.
CTACellulose Triacetate.
Cumulative ExposureThe summation of exposures of an organism to a chemical over a period of time.
CyanobacteriaSingle celled Organisms similar to bacteria, except it contains the green pigment chlorophyll, which traps the energy of sunlight and enables these organisms to carry on photosynthesis.
CyanosisA dusty bluish or purplish discoloration of the skin or mucous membranes due to insufficient oxygen in the blood, as could be caused by excessive nitrates in drinking water and methemoglobinemia in infants
CycleA series of steps which ultimately lead back to the starting point.
Cycles of ConcentrationThe measure of the concentration of a specific impurity in the boiler water divided by the concentration of the same impurity in the feedwater.
Cyclone SeparatorA Cylindrical device that separates water droplets from steam through centrifugal force.
CyclosporaA genus of protozoa parasites belonging to the order Coccidia and the phylum Apicomplexa. Carried in viably unfiltered water supply.
DamperA device that partially or totally inhibits the flow of air or combustion gases through ductwork.
Data PlateA plate attached to a piece of equipment such as a motor or safety valve that provides important information about the equipment.
DateometerA small calendar disk attached to motors and equipment to indicate the year in which the last maintenance service was performed.
Day TankA tank used to store chemicals.
Dead EndThe end of a water main which is not connected to other parts of the distribution system by means of a connecting loop of pipe.
Dead-End FiltrationA flow pattern in which all water flows through the medium or membrane thus allowing a buildup of particulate layer on or near the surface of the medium and requiring periodic back washing, repeated cleaning or cartridge replacement.
DeaeratorAn open heat exchanger that removes dissolved gases from the feedwater going to a boiler.
DealkalizationAny process for the reduction of alkalinity in a water supply. Usually done by a chemical feed process or combined cation and anion ion exchange systems.
DecantTo draw off the upper layer of liquid after the heavier material has settled.
Decatherm10 Therms or 1,000,000 Btu.
DecationizeThe exchange of cations for hydrogen ions by strong acid cation exchanger operated in the hydrogen form.
DechlorinationThe deliberate removal of chlorine from water. The partial or complete reduction or residual chlorine by any chemical or physical process.
DecolorizationThe process of removing color bodies such as tannins or humic acid from water by means of oxidation, coagulation/filtration, adsorption, or ion exchange.
DecompositionThe conversion of chemically unstable materials to more stable forms by chemical or biological action.
Decross-LinkingThe alteration of an ion exchange resin structure by destruction of the cross-link polymer as result of a very aggressive chemical attack or heat.
DefluoridationThe removal of excess fluoride in drinking water to prevent the mottling of teeth.
Degassing/ Degasify/ DegasificationThe removal of dissolved gases such as carbon dioxide, methane, hydrogen Sulfide and oxygen.
DegradationThe removal of all ionized minerals and salts from a solution by a two phase ion exchange procedure.
DeionizationRemoval of ions from water by exchange with other ions associated with fixed charges on a resin.
Delivered WaterThe finished product water from a public or private utility water plant which is carried through a water main network of pipes and arrives at the point of use.
Delta PThe pressure drop or loss by flowing water in a pressurized system as the result of the velocity and turbulence of the flowing water, restrictions the water flow through, and roughness of surfaces the water flows past.
Demand Initiated Regeneration (DIR)A method of automatically initiating regeneration of recycling in filters, deionizers, or softeners after a predetermined metered volume of water has been processed.
DemineralizerA highly efficient ion-exchange process generally used for high-pressure boilers.
DenitrificationThe biochemical conversion of nitrate and nitrite nitrogen in the soil dissolved in water to gaseous nitrogen.
Depth FiltrationA filtration process in which water flows through progressively smaller pore spaces in a filter media bed.
DesaltingThe removal of dissolved inorganic solids from a solution such as water to produce a liquid which is free of dissolved salts.
DesiccantA drying agent, such as activated alumina, calcium chloride, silica gel or zinc chloride.
DesiccationA process used to thoroughly dry air.
DesiccatorA closed container into which heated weighing or drying dishes are placed to cool in a dry environment.
DesiliconizationAn ion exchange process designed for reduction of silica from a water supply.
DesorptionThe opposite of adsorption.
DestratificationThe development of vertical mining within a lake or reservoir to eliminate separate layers of temperature, plant, or animal life.
DesulfovibrioA sulfate reducing bacteria in water which can convert sulfates and elemental sulfur to sulfide, thereby creating hydrogen sulfide gas and the concomitant "rotten egg" order in water supplies.
DesuperheatingRemoving heat from super heated steam to make it suitable for process.
Detention LagThe time period between the moment a change is made and the moment when such a change is finally sensed by the associated measuring instrument.
Detention TimeThe theoretical time required for a small amount of water to pass through a tank at a given flow rate.
Dew PointThe temperature to which air must be cooled to cause condensation of water vapor it contains.
DewaterTo remove or separate a portion of the water present in a sludge or slurry.
DezincificationA corrosion process that removes zinc from brass but leaves the copper in place.
Diagonal StaysBraces that are installed in a firetube boiler to keep the upper portions of the tube sheets above the tubes from bulging outward due to internal pressure.
DialysisThe separation of components of a solution by diffusion through a semi permeable membrane which is capable of passing certain ions or molecules while rejecting others.
Diaphragm PumpA positive displacement pump in which the reciprocating piston is separate from the solution by a flexible diaphragm, thus protecting the piston from corrosion and erosion and avoiding related problems with packing seals.
Diaphragm ValveA valve that uses a flexible diaphragm as the movable sealing surface.
DiatomA type of microscopic algae with cell walls that contain silica.
Diatomaceous EarthA fine, siliceous earth composed mainly of the skeletal remains of diatoms, a type of free floating, microscopic plant found in the ocean.
Diatomaceous Earth Filtration (DE Filtration) A filtration method resulting in substantial particulate removal, that uses a process in which, a precoat cake of diatomaceous earth filter media is deposited on a support membrane and while the water if filtered by passing through the cake of the septum, additional filter media, known as body feed, is continuously added to the feed water to maintain the permeability of the filter cake.
Diatomic MoleculeA molecule containing only 2 atoms.
DICDissolved Inorganic Carbon.
Dielectric FittingA plumbing fitting made of an electrical nonconductor used to control galvanic corrosion when joining pipes of dissimilar metals.
Differential PressureThe difference between to pressures measured at different points within the same process.
Differential TemperatureThe difference between to temperatures measured at different points within the same process.
DiffusionThe movement of suspended or dissolved particles from a more concentrated to a less concentrated region as a results of the random movement of individual particles.
Diffusion FeederA chemical feed system in which chemicals are added to a water stream in controller quantities for pipe line or metal surface protection and/or disinfection methods.
Diffusion RingA stationary vane in the pump casing.
DigestionThe process by which complex organic materials are broken down and decomposed into simpler substances as result of a chemical or biological reaction or a combination of reactions.
Digital ReadoutUse of numbers to indicate the value of measurement of a variable. The readout of an instrument by a direct, numerical reading or the measured value.
Digital SignalAn instantaneous signal used to implement a one-time action. For example, digital signals are used to shift the position of solenoid-operated valves, to detect the position of a level switch.
Dihydrogen OxideWater.
Dilute SolutionA solution that has been made weaker usually by the addition of water.
DilutionThe act of adding more solvent or water to a given solution to make it less concentrated.
DimicticLakes and reservoirs which freeze over and normally go through two stratification and two mixing cycles within a year.
DIRDemand Initiated Regeneration.
Direct FiltrationA filtration method of treating water which consists of the addition of coagulant chemicals, flash mixing, coagulation, minimal flocculation and filtrations.
Dirt PocketThe pipe nipple installed on the bottom of the drip leg that catches rust and weld slag.
Discharge HeadThe pressure measured at the center line of a pump discharge and very closely to the discharge flange, converted into feet.
Discharge PipingThe piping attached to the outlet side of a component, that carries the outlet flow.
Disc Steam TrapA comparatively small steam trap that uses a flat, round disc as the means of opening and losing the outlet orifice.
DisinfectionDisinfection is the process of killing microorganisms, usually by one of a variety of chemical agents, such as formaldehyde and sodium hypochlorite. Disinfection lowers the number of microorganisms without necessarily killing all those present. Although total killing of all organisms is virtually impossible, sterilization will reduce the number of organisms to a safe predetermined level. Sterilization can generally only be achieved routinely by heat, gamma irradiation, ethylene oxide, and in certain cases, special filtration. Of these methods, only filtration is suitable for mass sterilization of water and none is suitable for sterilization of water treatment equipment used in hemodialysis facilities. However, a proprietary chemical disinfectant incorporating peracetic acid as the active ingredient has been qualified as a sterilant and this agent may be suitable for sterilization of certain water system components.
Disinfection Byproduct A compound formed by the reaction of a disinfectant such as chlorine with organic material in the water supply.
DispersantA chemical added to water which causes particulates in water to remain in suspension.
Dispersing AgentA material that increases the stability of particles in a liquid.
DisplacementThe volume of fluid forced out of a full container when another body is forced into the container.
DisplacerA long, fairly heavy cylindrical float of small diameter used to measure liquid level in a tank or vessel.
Disposable ComponentAny component of a piece of water treatment equipment or water treatment system which is manufactured to be disposed of instead of repaired or used.
DissociationThe process by which a chemical combination breaks up into simpler constituents such as atoms, groups of atoms, ions or multiple different molecules.
Dissolved Inorganic Carbon (DIC)The fraction of inorganic carbon in water that passes through a 0.45 micron pore diameter filter.
Dissolved GasesGases that have gone into solution in water.
Dissolved MatterThe potion of matter or solids, exclusive of gases, which is dispersed in water to produce a homogenous liquid. By definition should pass through a 0.45 micro pore diameter membrane filter.
Dissolved Organic Carbon (DOC)The fraction of total organic carbon in water that passes though a 0.45 micron pore diameter filter.
Dissolved Oxygen (DO) Measure of water quality indicating free oxygen dissolved in water.
Dissolved SolidsSolid impurities that have gone into solution.
DistillateThe product water or condensate, which is mineral free and potable from a distiller unit.
Distillate Fuel OilA fuel produced by distilling crude oil.
DistillationThe process of separating the water from the organic and inorganic contaminants through a combination of evaporation, cooling, and condensation.
Distilled WaterWater which has been cleansed by passing through one or more evaporation condensation cycles unit it contains a very low amount of dissolved solids.
DistributorA fitting, usually installed at the top and bottom of the tank in a loose media system, which is designed to produce even flow through all sections of an ion exchanger or filter media bed and to function as a retainer of the media in the tank.
DiavalentHaving a valence of two, such as the ferrous ion.
DiversionThe use of part of a stream flow as a water supply.
Divinylbenzene (DVB)A polymerization monomer used as cross linking agent.
DOCDissolved Organic Carbon.
DolomiteA Carbon mineral of calcium and magnesium found in nature in extensive beds of compact limestone and marble that are rich in magnesium carbonate.
DosageThe quantity of a chemical administered to an organism.
DoseThe actual quantity of a chemical to which an organism is exposed.
Dose EquivalentThe product of the absorbed does from ionizing radiation and such factors as account for differences in biological effectiveness due to the type of radiation and its distribution in the body as specified by the International Commission on Radio-logical Units and Measurements (ICRU).
Dose ResponseA quantitative relationship between the dose of a chemical and an effect caused by the chemical.
Dose Response CurveA graphical presentation of the relationship between degree of exposure to a chemical and observed to a substance and the extent of toxic injury or disease.
Dose Response EvaluationA component of risk assessment that describes the quantitative relationship between the amount of exposure to a substance and the extent of toxic injury or disease.
Dose Response RelationshipThe quantitative relationship between the amount of exposure to a substance and the extent of toxic injury produced.
Double-Acting PumpA reciprocating pump that moves fluid in both directions of stroke.
Double Block and BleedA valve configuration that consist of two automatic shutoff valves arranged in series, with a vent or bleed valve between them that vents outdoors.
Double-Seated ValveA control valve that has two discs on one stem and two seats in the body.
Double-Suction PumpA Pump with a casing and impeller designed to allow a liquid to flow into both sides (eyes) of the impeller at once.
Downcomer TubesTubes that contain the cooler, descending water.
DownflowThe term used to designate the direction in which water or regenerant flows through an ion exchange or filter media bed.
Downflow SofteningThe softening process in which raw water enters at the top of the softener bed column and passes downward through the cation resin and out the bottom.
DPDA method of measuring the chlorine residual in water.
DraftThe movement of air and/or gases of combustion from a point of higher pressure to a point of lower pressure.
Draft LossThe loss of available draft due to friction and other pressure losses as the flue gases flow through the combustion gas passageways.
Draft SystemConsists of the equipment, controls, and ductwork that deliver air to the boiler furnace area for combustion of the fuel, and then conduct the spent combustion gases to the atmosphere.
DrainA pipe, conduit, or receptacle in a building which carries liquids by gravity to waste.
Drainable SuperheaterA superheater configured so that condensate in the super heater tubes migrates to a low point from which it can be drained.
Drainage BasinThe area of land that drains water, sediment, and dissolved materials to a common outlet at some point along a stream channel.
Drain LineA pipeline which is used to carry back wash water, regeneration wastes, and/or rinse water from a water treatment system to a drainage receptacle or waste system.
DrawdownThe drop in water table or level of water in the ground when water is being pumped from a well.
Drift (Cooling Water Treatment)The loss of water that is en-trained in the stack discharge.
Drilled WellA well constructed by either cable tool or rotary methods which operates by cutting or abrasion.
Drinking WaterA water, treated, or untreated, which is intended for human use and consumption and considered to be free from harmful chemicals and disease causing bacteria, cysts, viruses or other microorganisms.
Drinking Water StandardsStandards that define allowable water quality limits for potable and domestic water supplies.
Drip LegA downward extension from a steam distribution line or piece of heat exchange equipment where condensate is allowed to drain.
Driven WellA shallow, usually small well, constructed without the aid of any drilling, boring or jetting device bu driving a series of connected pipe lengths into unconsolidated material to a water-bearing stratum.
Drum DesuperheaterAn attemperator that diverts part of the super-heated steam through a heat exchanger in the boiler mud drum.
Drum Pressure Control ValveA control valve that is configured so as to maintain a constant pressure on the steam drum of a watertube boiler or the shell of a firetube boiler at all times.
Dryback Scotch Marine BoilerA firetube boiler with a refractory-lined chamber at the rear of the boiler that is used to direct the combustion gases from the flue furnace to the first pass of tubes.
Dry PipeAn upside-down T-shaped pipe connected to the main steam outlet from either a firetube or watertube boiler that removes entrained droplets of boiler water from the steam.
Dry Salt Saturator TankA brine tank, usually full of undissolved salt and with saturated brine below the undissolved salt.
Dry SheetThe metal that is an extension of the cylindrical shell of a firetube boiler, past the tube sheet. The dry sheet forms the smoke box.
"D" Style watertube boilerA watertube boiler with a top steam and water drum and a bottom mud drum that are interconnected by banks of tubes that form a "D" shape. The open area of the "D" is for the combustion of the fuel.
D-slide ValveA valve that controls the movement of steam into and out of the steam cylinder in a duplex pump.
Dual ChamberA water processing system composed of two separate tanks vertically connected, one above the other and operated by one common set of valve controls.
Dual Function MediaAny filter or ion exchange media which is used to perform two treatment steps in an application.
DuctilityThe plasticity exhibited by a material under tension loading.
Duplex PumpA steam-driven, reciprocating, positive-displacement, double-acting pump with two steam cylinders and two liquid cylinders.
Duplex StrainersRemove solid particles from the fuel oil in fuel oil systems.
Dug WellA shallow large diameter well constructed by excavating with power machinery or hand tools instead of drilling or driving.
DWELL (Drinking Water Equivalent LevelEstimated exposure which is interpreted to be protective for noncarcinogenic endpoints of toxicity over a lifetime of exposure.
Dynamic PressureWhen a pump is operating, the vertical distance from a reference point to the hydraulic grade line in the dynamic head.
Dynamic ReactionAn ion exchange reaction which takes place as the water moves past the exchange resin or resins.
Dynamic SystemA process or system in which motion occurs, as compared to static conditions with no motion.
Dynamic Water PressureThe water pressure at the inlet to a dynamic water processing system.
E. ColiEscherichia Coli Bacteria.
EconomizerA series, or bank, of tubes used to recovery heat from the boiler flue gas by using it to heat the boiler feedwater.
EddyA circular movement or whirlpool occurring in flowing water due to currents created by various obstructions or dynamic forces in the water.
EDTAAethylene Diamine Tetraacetic Acid.
EductorA venturi with an opening at the throat which will educt air or liquid.
Effective Corrosion Inhibitor ResidualA concentration of corrosion inhibitor sufficient to form a protective coating on the interior walls of a pipe, reducing its corrosion.
Effective RangeThe portion of the design range in which an instrument has acceptable accuracy.
Effective SizeA measure of the diameter of particles in a media bed or resin bed.
EfficiencyThe comparison of energy output to energy input in a piece of equipment or in a system.
EjectorA device used to disperse a chemical solution into water being treated.
Ejector PumpA shallow or deep well pump operating on the venturi principle. Also known as Jet Pump.
Electric BoilerBoiler that has heat produced by electric resistance coils or electrodes.
Electrochemical ReactionChemical changes produced by electricity or the production of electricity by chemical changes.
Electrochemical SeriesA list of metals with the standard electrode potentials given in volts.
ElectrodialysisA dialysis process using semipermeable membranes in which ions migrate through the membranes from a less concentrated to a more concentrated solution as a result of the ions' respective attractions to a positive electrode and a negative electrode.
ElectrolyteA substance which, when dissolved in water, separates into two or more ions which can carry an electric current.
Electrolytic CellA device in which the chemical decomposition of material causes an electric current to flow.
Electromotive Force (E.M.F.)The electrical pressure available to cause a flow of current when an electrical circuit is closed.
Electromotive SeriesA list of metals and alloys presented in the order of their tendency to corrode.
ElectronA negatively charged particle that revolves around the nucleus of an atom.
Electronic Flue Gas Analyzer Device used to analyze flue gas for temperature, gases, draft, and smoke.
Electrostatic Precipitator A device used to separate flash particles from the flue gas stream before it goes out the stack.
ElutionThe process of separating or washing out adsorbed material, especially by use of a solvent.
Emergency PlanA document that details procedures, exit routes, and assembly areas for facility personnel in the event of an emergency.
Emission FactorAn expression of the rate of pollutant production per unit of fuel input.
Emission SpectroscopyA chemical analytical technique used to determine metal elements in water by measuring the well defined characteristic radiation given off by each respective element as the thermally excited element returns from an atomic vapor state to its fundamental state.
Empty Bed Contact TimeThe empty bed contact time (EBCT) is used as a measure of how much contact occurs between particles, such as activated carbon, and water as the water flow through a bed of the particles. As the EBCT increases, the time available for the particles to absorb solutes from the water also increases, as does the amount of solute removed from the water during its transit through the bed. EBCT is calculated from: EBCT = Vm/Q where Vm is the colume of particles in the bed the Q is the volumetric flow rate. A consistent set of units must be used when calculating EBCT with this equation. For example, if Vm is given in ft³ then Q must be expressed in ft³/min for the EBCT to have units of minutes. Values of Q can be converted from other units, such as GPM, to ft/min using the conversion factor.
EmulsificationThe dispersion or suspension of fine particles or globules of one or more liquids in another liquid.
End BellsDevices used to hold the rotor and stator of a motor in position.
Endothermic A term used to describe a process or change in which heat is absorbed and that requires high temperature for initiation and maintenance.
EndotoxinBacterial lipopolysaccharide, a substance released from the cell walls of gram-negative bacteria when the organism is broken down.
EndrinA pesticide toxic to freshwater and marine aquatic life that produces adverse health effects in domestic water supplies.
Energy Grade Line (EGL)A line that represents the elevation of energy head of water flowing in a pipe, conduit, or channel.
EntericOf intestinal origin, especially applied to wastes or bacteria.
Enthalpy Total heat in the steam.
EntrainTo trap bubbles in water either mechanically through turbulence or chemically through a reaction.
EntrainmentThe process where solid or liquid particles are carried along with steam flow.
EntropyThe capacity of a system or a body to hold energy that is not available for changing the temperature of the system or for doing work.
EnzymesA large class of complex proteinaceous molecules, which act as catalysts in biochemical reactions, and, as produced by living cells, can bring about digestion of organic molecules into smaller units that can be used by living cells.
Equalizing LineA small line used to equalize the temperatures and/or pressures on both sides of a large valve before opening it. This is sometimes called a bypass line.
ErrorThe amount of deviation of a measurement from the set point.
EsterA compound formed by the reaction between an acid and an alcohol with the elimination of a molecule of water.
EtchingThe deterioration by chemical change on the surface of glassware caused by the action of high temperatures and detergents.
Ethyl AlcoholThe most common variety of alcohol. Also known as Grain alcohol or Ethanol.
Ethylene Diammine Tetraacetic Acid (EDTA)A Chelating agent.
EutrophicationThe increase in the nutrients levels of a lake or other body of water.
Evaporation The process by which a substance is changed from the liquid to the vapor state.
Evaporation ChamberThe part of a distillation system in which water is changed into vapor.
Evaporation TestA test that allows a low water condition to occur in the boiler in order to test the low water fuel cutoff switch.
EvaporatorA set of heat exchangers that produces water suitable for boiler use from water that contains large quantities of impurities.
EvaporiteA mineral precipitated as result of evaporation, such as the solids left behind in the distillation process.
EvapotranspirationThe combined processes of evaporation and transpiration.
Excess AirThe amount of air added to the combustion process over and above that which is theoretically necessary.
Exchange SitesLocations on each bead of ion exchange resin which hold mobile ions that are available for exchange with other ions in the solution that passes through the resin bed.
Exchange VelocityThe rate at which one ion is displaced in favor of another in an ion exchange.
ExemptionA state with primary enforcement responsibilities under the US Safe Drinking Water Act may relieve a public water system from a requirement respecting an MCL, treatment technique, or both, by granting an exemption if certain conditions exist. These are 1) The system cannot comply with an MCL or treatment technique due to compelling factors which may include economic factors; 2) the system was in operation on the effective date of the MCL or treatment technique requirement; 3) the exemption will not result in an unreasonable public health risk.
ExhaustionThe state of an ion exchanger or other adsorbent that is no longer capable of useful ion exchange due to the depletion of the initial supply of available exchangeable ions.
Exhaustion Wave FrontThe boundary between the absence and presence of a contaminant as it passes through a media bed.
ExothermicA term used to describe a chemical process in which heat is released.
ExposureContact with a chemical or physical agent.
Exposure AssessmentThe determination or est of the magnitude of exposure to a chemical.
Exposure CoefficientTerm which combines information on the frequency, mode, and magnitude of contact with contaminated medium to yield a quantitative value of the amount of contaminated medium contacted per day.
Exposure LevelThe amount of a chemical at the absorptive surfaces of an organism.
Expansion BendA section of piping, commonly formed in a "U" shape, that provides flexibility for expansion and contraction of the piping with changes in temperature.
Exposed-tube (dry-top) vertical boilerA firetube boiler with fire tubes extending several inches through the steam space at the top before ending at the tube sheet.
External Header Cast Iron SectionalContains cast iron sections individually connected to external manifolds with screwed nipples.
Externally fired firetube boilerA boiler with a separate furnace area that is usually built of refractory brick.
External Treatment Boiler water treated before it enters the boiler to remove scale-forming salts, oxygen, and noncondensable gases.
Extractive CEMSA monitoring system that withdraws a sample of the flue gas stream, conditions the sample, analyzes the conditioned sample, and then provides a readout of the flue gas condition.
ExtrapolationEstimation of unknown values by extending or projecting from known values.
FACFree Available Chlorine.
Factor Of EvaporationThe heat added to the water in a actual boiler in Btu/lb and divided by 970.3.
Facultative OrganismsFacultative microbes can use either molecular oxygen or oxygen obtained from food material such as sulfate or nitrate ions.
Fast RinseA rinse process in which the rinse water is applied to the softener bed at the end of brine regeneration at a faster rate of flow than that for which the brine was applied.
FeatheringThe point when a safety valve is about to lift.
Fecal Coliform BacteriaBacteria found in the intestinal tracts of mammals and there in fecal matter.
Feed and BleedAn ultrafiltration term borrowed from old fashioned boiler operators.
FeedbackThe circulating action between a sensor measuring a process variable and the controller which controls or adjusts the process variable.
Feedback Transmitter A transmitter used to provide confirmation that a valve or damper actuator has made a change as commanded.
Feed PressureThe pressure at which water is supplied to a water treatment device.
Feedwater A mixture of condensate and makeup water that is provided to the boiler to make steam.
Feedwater Water entering a purification system or an individual piece of purification equipment, such as an ultrafilter or reverse osmosis system.
Feedwater Line The piping that carries the feedwater from the feedwater pump to the boilers.
Feedwater Pump A pump that sends the returned condensate and any makeup water into the boiler.
Feedwater System Consists of all equipment, controls and piping that prepare and treat the water for use in the boiler, put the water into the boiler, and maintain a normal, safe amount of water in the boiler.
Ferric IronSmall solid iron particles containing trivalent iron, usually as gelatinous ferric hydroxide or ferric oxide, which are suspended in water and visible as rusty water.
Ferrous IronA divalent iron ion, usually as ferrous bicarbonate which when dissolved in water, produces clear solution.
Fick's Law of DiffusionA law of chemistry and physics; the rate of diffusion of one substance in another is proportional to the negative gradient of the concentration of the first substance.
Field-Assembled Boiler A boiler of large size that cannot be shipped as a completed unit by the manufacturer to the site where it will be placed in service.
Field-Erected Boiler Boiler that must be erected in the field because of its size and complexity.
Filming Amine A chemical that prevents corrosion of condensate piping by providing a protective barrier.
FilterA device installed as part of the water system through which water flows for the purpose of removing turbidity, taste, color, iron, or odor.
Filter - AGThe trade name for an aluminum silicate granular product used as a general purpose filter medium.
Filter AidAn Agent that improves filtering effectiveness in some way, such as enhancing the retention of particles or increasing the permeability of the filter to water flow.
Filter CakeSolids deposited on top of a filter media bed, often by use of chemically feeding a coagulant or filter aid.
Filter MediaThe selected materials in a filter that form the barrier to the passage of filterable suspended solids or dissolved molecules.
Filtrate1. The effluent liquid for a filter system. 2. The liquid remaining after removal of solids.
FiltrationThe process of separating solids from a liquid by means of a porous substance such as a permeable fabric or membrane or layers of inert media.
Final Element The device that actually causes the change in the process.
Fine MeshThe smaller end of the size spectrum from water treatment media such as ion exchange resin beads.
FinesExtremely small particles which are smaller than the specific size for the medium.
Finished WaterProduct water as it leaves the municipal treatment plant for delivery to consumers.
Firebox The part of the boiler where combustion of fuel takes place.
Firebox Boiler A fire-tube boiler In which an arch-shaped furnace is surrounded on both sides by a water leg area.
Fired Vessel A pressure vessel that includes a burner or combustion equipment of some kind.
Fire Extinguisher Portable unit used to put out small fires or contain larger fires until the company fire brigade or the fire department arrives.
Fire Point The lowest temperature at which the vapor given off by a substance will ignite and burn for at least 5 sec when exposed to an open flame.
Firetube Boiler Has heat and gases of combustion passing through tubes that are surrounded by water.
Firing Rate The rate at which fuel is being burned by a burner at any particular time.
First DrawThe water that immediately comes out when a tap is opened.
First Draw SampleA one-liter sample of tap water, collected in accordance with CFR Section 141.89(b)(2), that has been standing in plumbing pipes at least six hours and is collected without flushing tap.
First Law Of Thermodynamics Energy cannot be created or destroyed, but can be changed from one form to another.
Fittings Trim found on the boiler that is used for safety, and/or efficiency.
Fit-up The process of fitting and rolling the tubes into the drums of a new watertube boiler.
Fix (Sample)A sample is fixed in the field by adding chemicals that prevent the water quality indicators of interest in the sample from changing before final measurements are preformed in the lab.
Fixed BedThe filter or ion exchange medium retained in a vessel.
Fixed Carbon The burnable remainder of coal left when coal is heated and the volatile matter is driven off.
Fixed MatterThe residue that remains behind despite action to expel it.
Fixed SolidsThe term used in the lab analysis of the solid's content of water to define the residue of total suspended and/or dissolved solids after ignition or heating for specified time at specified temp.
FixtureAny permanently installed receptacle that will hold water, sink, lavatory or water closet.
FlagellatesMicroorganisms that move by the action of tail like projections.
Flame Failure A situation where the flame in a furnace fails to light properly or goes out during operation as a result of a problem with the burner-related equipment.
Flame Impingement A condition where flame from burning fuel continually strikes the boiler surfaces or refractory brick.
Flame PolishedMelted by a flame to smooth out irregularities.
Flame Propagation Rate The rate at which the flame can ignite the incoming air-fuel mixture, in feet per second.
Flame Safeguard System The collection of automatic control devices that ensure safe operation of the combustion equipment.
Flame ScannerA device that proves that the pilot and main burner flames have been established and remain in service.
Flame SensorA device in a flame scanner used to sense the pilot and the main flame in the burner.
FlarebackFlames discharging from the boiler through access doors or ports, caused by delayed ignition or furnace pressure buildup.
FlashThe portion of a super heated fluid that is converted to vapor when its pressure is reduced as in flash distillation.
FlashbackThe condition where a flame travels upwind and into the burner assembly.
Flash DistillationA distillation process in which hot incoming water flows into a chamber in which pressure is low, causing some of the water to flash (turn quickly to steam).
Flash EconomizerA heat recovery system used to reclaim the heat from the boiler blowdown water and used in conjunction with the continuous blow down system.
Flash PointThe lowest temperature at which the vapor given off by a substance will make a flash of flame, but not continue to burn, when an open flame is passed over it.
Flash SteamSteam that is instantly produced when very hot water is released to a lower pressure and, thus a lower boiling temperature.
Flash TankA pressure vessel in which condensate or other very hot water under a high temperature and pressure is allowed to partially flash into steam.
Flat Gauge GlassType of gauge glass used for pressures over 250 PSI.
Flexible JointIs used to allow for expansion and contraction of steam or water lines.
Flexible Tube Watertuber BoilerA boiler design in which the tubes exposed to the combustion gases are sharply bent to provide the maximum possible flexibility.
Float1. A device that is lighter than water, that floats in or on the surface of the water. 2. The inventory of resin in portable exchange deionization operations.
Float & Thermostatic Steam TrapContains a thermostatic bellows or other thermostatic element and also contains a steel ball float connected to a discharge valve by a linkage.
Floc1. A very fine, fluffy type mass formed by the coming together of a number of fine suspended particles. 2. A clump of solids formed in sewage by biological or chemical reaction.
FlocculationA practice common in municipal water treatment in which destabilized colloidal particles are formed into larger particles (flocs), usually by stirring. The floc is removed from the water by settling or filtration. The process may also incorporate the addition of such compounds as synthetic poly-electrolytes, which increases the size of the flocs, thereby making them more easily removed by settling or filtration. Removal of colloids by flocculation is done in combination with coagulation.
FlocculentA substance, used in combination with coagulants, which causes submicroscopic suspended matter (colloids) to aggregate into larger particles which can be removed by settling or filtration.
Flow ControllerAn in-line device or orifice fitting which will regulate and control flow of water or regenerant over a broad range of inlet water pressures.
Flow Control ValveA cylindrical pressure compensating valve installed to regulate the flow of water.
Flow RateThe quantity of water or regenerant which passes a given point in a specified unit of time, often expressed in US GPM.
Flow Sensor A device that measures flow rate and can control or measure an action when the actual flow rate falls outside the present limits.
Flow SwitchA device which, according to preset flow rate conditions, causes an action when the actual flow rate falls outside the preset limits.
Flow Velocity The flow of fluid at any point in a water treatment system may be expressed quantitatively in two ways, either in terms of the volume of fluid passing the point in a given timer or in terms of the velocity with which fluid passed the point. The flow velocity depends on the geometry of the conduit through which the fluid flows and is related to the volumetric flow by: V=Q/A Where A is the cross-sectional area of the conduit. As an example the table below shows the volumetric flow rate as a function of flow velocity in PVC Schedule 80 pipe of different diameters.
Flue Gas RecirculationThe process of reintroducing a stream of the spent flue gases from the breeching or stack back into the combustion airstream.
FluidAny material that can flow from one point to another. Fluids can be liquids or gases.
Fluidization A flowing liquid impinging on a bed of particles imparts some of its momentum to each particle. The imparted momentum is in the direction of the fluid flow. The particles are held to the floor of their container by gravity and to each other by adhesive forces. If the fluid flow is upward through the bed of particles, and if the transfer of momentum from the fluid to the particles is sufficient to overcome both the gravitational and the adhesive forces, the particles become suspended, or fluidized, in the fluid stream.
Fluidized Bed BoilerA boiler in which fuels are burned in a bed of inert materials such as limestone pellets or sand.
FluoresceinAn orange- red compound that exhibits intense fluorescence in alkaline solutions and is used to dye water in order to trace its course and movement.
FluorideAn ion of hydrofluoric acid which may occur naturally in water supplies or be added by municipal processes for the prevention of dental cavities. Fluoride is considered toxic in the hemodialysis setting and has been implicated with renal bone disease.
FluorosisAn abnormal condition caused by excessive intake of fluorine, characterized by mottling of the teeth.
FlushTo open a cold water tap to clear out all the water which may have been sitting for a long time.
FlushingIn municipal water systems, a method used to clean water distribution lines.
FluxIn crossflow filtration, the flow rate of product water through a reverse osmosis, electrodialysis, or ultrafiltration membrane.
Flux Rate The rate per unit of area at which water passes through a semi-permeable membrane, such as those used for ultratfiltration or reverse osmosis.
Fly AshAsh from the combustion of coal or other solid fuels that is carried along with the draft through a boiler furnace and ductwork.
FMAFree Mineral Acidity.
FoamingThe development of froth on the surface of the boiler water.
Foot-PoundA unit of work equal to the movement of a 1-lb object over a distance of 1 ft.
Foot ValveA check valve installed at the bottom of the suction line on a negative suction pump that keeps the suction line primed when the pump shuts down.
Forced Circulation A variation in watertube boiler design in which boiler water circulation through the tubes is enhanced by a pump.
Forced DraftThe discharge of combustion air from a fan into a furnace to combine with the fuel for combustion.
FoulingThe deposition of insoluble materials, such as bacteria, colloids, oxides and water-borne debris, on to the surface of a reverse osmosis or ultrafiltration membrane. Fouling is associated with decreased flux rates and may also reduce the rejection rates of reverse osmosis membranes.
FractionateTo separate into fractions or parts.
Free Acid FormThe regenerated form of a weak acid cation exchanger.
Free Available Chlorine (FAC)The portion of the total available residual chlorine composed of dissolved chlorine gas, hypochlorous acid and or hypochlorite ion remaining in water after chlorination.
Free Base FormThe regenerated form of a weak basic anion exchanger.
FreeboardThe vertical distance between the top of a filter media bed and the overflow or collector.
Free Carbon DioxideCarbon dioxide present in water as gas or as carbonic acid but not including that carbon dioxide in combination as in carbonates or bicarbonates.
Free Residual ChlorinationThe application of chlorine to water to produce a free available chlorine residual equal to at least 80% of the total residual chlorine.
FrequencyThe number of cycles of the AC sine wave in one second. Frequency is measured in hertz (Hz) or cycles per second.
FriabilityAn expression of the ability of ion exchange beads to resist cracking under hydrostatic operation.
Friction Head (Loss)The pressure loss associated with friction in the pump piping and fittings, converted into equivalent feed of static head.
Fuel NoxNox that is formed as a result of the oxidation of nitrogen in the fuel.
Fuel SystemConsists of all the equipment, controls and piping that deliver the fuel to the boilers combustion equipment control the combustion process.
Fuel-To-Steam EfficiencyThe percentage of the heat content of the fuel that is transferred into the boiler water.
Fullers EarthA clayish substance of hydrous aluminum silicate used as a filter aid in coagulation.
Fulvic AcidsAcidic substances which are found in humus soils and which may become suspended in water.
Furnace Volume:Amount of space available in a furnace to complete combustion.
Fusible PlugA temperature sensitive device that causes an audible alarm when exposed to excessive temperature.
Fyrite AnalyzerInstrument used to measure percentage of carbon dioxide in the gases of combustion.
GaggingApplication of a clamp on a safety valve spindle to keep the valve in full closed position during a hydrostatic test.
Gallionella FerrugineaOne of several types of bacteria that use iron in their metabolism and are capable of depositing gelatinous ferric hydroxide.
Galvanic CellA cell, consisting of dissimilar metals in contact with each other and with electrolyte, which generates an electrical current.
Galvanic CorrosionForm of corrosion which occurs in a galvanic cell in which one of the metals dissolves and goes into solution.
Galvanic SeriesA list of metals and alloys presented in the order of their tendency to corrode.
GalvanizeTo coat a metal with zinc.
GalvanometerUsed to measure small electric currents.
Gamma DecayA type of radiation, gamma radiation, where gamma rays are photons and are without rest mass or charge.
GarnetA group of hard, reddish, glassy, mineral sands made up of silicates of base metals.
GA SaltA very coarse grainy salt of "Ground Alum" size, which was formerly used for regeneration zeolite water softeners, sometimes used coincidentally with alum as a coagulant.
Gas AnalyzerUsed to analyze the gases of combustion to determine combustion efficiency.
Gas CalorimeterUsed to determine the Btu content of natural gas.
Gas ChromatographySample mixture is vaporized and injected into a stream of carrier gas such as helium or nitrogen which is moving through a column containing solid medium or medium coated with a relatively nonvolatile liquid.
Gas CockA manual quick-closing shutoff valve.
Gases Of CombustionGases produced by the combustion process.
Gas Leak DetectorDevice used to locate gas leaks in a boiler room.
Gas Mixing ChamberWhere air and gas mix before they enter the furnace in low pressure gas burners.
Gas Pressure RegulatorUsed to supply gas to the burner at pressure needed for combustion of the gas.
Gas Tungsten Arc WeldingA welding process in which a non-consumable tungsten electrode is used to provide the arc for welding.
Gas TurbineA rotating machine used to generate electricity from the flow of hot gases of combustion.
Gate ValveA valve used to stop or start flow. It has a wedge-like disc that is lowered into or raised out of the path of the fluid that flows through the valve.
Gauge GlassA tubular or flat glass connected to a water column that allows an operator to see the water level in the water column, and thus in the boiler, at a glance.
Gauge Glass Blowdown Valve Valve used to remove any sludge and sediment from gauge glass lines.
Gauge Pressure The pressure above atmospheric pressure. It is expressed as psig.
Gear Pump A rotary positive-displacement pump in which the liquid being pumped fills the open spaces between the teeth of rotating cylindrical gears and the pump housing.
Gel ResinA gellular resin form of ion exchanger as opposed to macroporous exchangers.
Gel ZeoliteA synthetic sodium alumina silicate cation exchange product that was very widely used in residential water softeners prior to the development of DVB/styrene cation resin.
Germicidal UltravioletAn ultraviolet light that peaks at 2,537 angstrom wave-length and is in a wavelength that lies between 200 and 300 nanometers.
Glauber's SaltAn anhydrous sodium sulfate salt compound.
Glauconite SandA mineral which is frequently used in depth filters.
Globe ValveA valve that has a tapered, rounded, or flat disc held horizontally on the stem.
GlutaraldehydeA general disinfectant for drinking water treatment equipment.
GlycerinA trihydroxy alcohol with sweet taste and syrup - like consistency.
GooseneckA portion of a service connection between the distribution system water main and a meter.
GPDGallons per day.
GPGGrains per gallon.
GPMGallons per minute.
GradeThe size of the pieces of coal.
Grains of HardnessAlthough the theoretical hardness of water is the sum of the concentrations of all metallic ions, other than alkali metals, it is commonly expressed as the equivalent concentration of calcium carbonate in grains. Ionic concentrations can be expressed in terms of their combining potential, the number of moles, or their masses in any of several conventions. In the English system masses are expressed in terms of pounds which contain 7000 grains each. Although considered outdated in most of the world, the US water purification industry continues to express hardness in units of grains/gal expressed as calcium carbonate. Grains/gal expressed as calcium carbonate can be converted to metric units by multiplying the former by 17.1 grains/gal expressed as calcium carbonate can also be converted into meq/L of a univalent ion, such as sodium (Na+) by multiplying by 0.342. Care must be taken in using these conversion factors to size equipment based on ion exchange principles since the ionic content of the water will depend on the type of ions present as well as their total mass.
GratesThe collection of horizontal or semi horizontal cast iron or steel components that support a burning mass of solid fuel and allow combustion air to pass through the fuel.
Gravel Support BedVarious layers of different sized gravel and coarse sand placed above the under-drain network to support filter or ion exchange media beds.
GravimetricA means of measuring unknown concentrations of water quality indicators in a sample by weighting a precipitate or residue of the sample.
Gravimetric MeasurementMeasurement on the basis of weight.
GrayThe SI unit of absorbed dose of ionizing radiation.
Grey WaterWaste water other than sewage.
GreensandA dark, coarse, sandy material sometimes used in iron removal.
Gross Alpha and Beta Particle Activitythe total radioactivity due to alpha or beta particle emissions as inferred from measurements on a dry sample.
Ground WaterWater found beneath the surface of the ground.
GroutingCement like fluid which is poured or injected into the bore hole during well drilling to seal crevices and to prevent contamination or loss of drilling mud.
Gulmite ScrewThe screw which holds the swivel part of a yoke connector for a portable exchange tank in place.
Gunning Materials Plastic refractory materials that are gunned, or sprayed, under pressure onto a surface.
GypsumA moderately insoluble calcium sulfate, containing 20.9% water, which is often used as a soil amendment to aid in building soil structure.
Half-LifeThe time required for half of the substance present at the beginning to dissipate or disintegrate.
HaliteA geological term for rock salt, mineral which is more than 95% sodium chloride. Also called native salt or fossil salt.
HalogensA family group of elements, including bromine, chlorine, fluorine, astatine, and iodine, which are extremely active chemicals.
HalophilicThriving in a salt environment.
Halophilic BacteriaSalt tolerant bacteria often found in solar salt which has not been fully kiln dried or in salt which may have been exposed to unsanitary conditions over a long period of time.
Hammer TestA test performed on the stays inside the boiler to check the integrity of each, relative to the others.
HandholeA small access hole used for looking and reaching into the boiler shell during inspections.
HardnessHardness was originally defined as a measure of the ability of water to precipitate soaps made from fatty carboxylic acids. These soaps precipitated in the presence of calcium and/or magnesium ions. Today hardness is used to describe the total concentration of calcium and magnesium, expressed as mg/L or calcium carbonate. It is generally calculated from measurement of calcium and magnesium ion present as well as their total mass.
Hardness as Calcium CarbonateThe value obtained when the hardness forming salts are calculated in terms of equivalent quantities of calcium carbonate.
Hard WaterWater containing total hardness in the amount of one grain per US gallon measured as calcium carbonate equivalent.
Hazardous MaterialA substance that could cause injury to personnel or damage to the environment.
HeadA vertical column of liquid that, due to its weight, exerts pressure on the bottom and sides of its container.
HeaderA large central pipe with two or more side outlets which is located at the bottom of a vessel containing water that has passed through a filter bed or ion exchange media bed.
Head LossThe reduction of water pressure, measured in psi, in hydraulic or plumbing system.
Health ContaminantAny substance or condition that may have any adverse effect on human health.
Health Effects ConcernExposure to contaminants at a toxicologically significant level as defined by the maximum contaminant levels for regulated contaminants or action levels for nonregulated contaminants
Health or safety ClaimMeans one or more of the following. 1) Any claim that the water treatment device or treatment component will remove or reduce a health related drinking water contaminant. 2) Any claim that the water treatment device or treatment component will remove or reduce a contaminant for which a national primary drinking water standard or treatment requirement has been established. 3) Any claim that the water treatment device or treatment component will remove or reduce a contaminant which has been determined to present a health risk by the United State Environmental Protection Agency.
Heat EnergyKinetic energy caused by molecular motion within a substance.
Heat ExchangerAny piece of equipment that transfers the heat from a heating medium into some other material.
Heating SurfaceThe part of the boiler that has heat and gases of combustion on one side and water on the other.
Heating ValueExpressed in BTU per gallon or per pound. Heating value varies with the type of fuel used.
Heat of VaporizationThe amount of additional heat needed for one medium to another or used to remove heat from or add heat to a fluid.
Heat SensorA device that opens and closes a switch in response to changes in the temperature.
Heat TransferMovement of heat from one substance to another that can be accomplished by radiation conduction or convection.
Heavy MetalsMetallic elements with atomic weights greater than 5, e.g. mercury, chromium, cadmium, arsenic, and lead.
HectareA measure of area in the metric system similar to an acre.
HeelThe lower zone of the ion exchange bed that is "passed by" in either the softening, deionization, or dealkalization mode or during the application of regenerates.
Helicobacter PyloriA pathogenic bacterium that has been shown to be associated with peptic duodenal ulcers in humans, although not all persons who have been found to harbor the organism are affected by ulcers.
HemeOrganic Iron, with deep red pigment which contains reduced iron.
Hemodialysis Grade WaterWater which meets the requirements set forth by the American National Standards for Hemodialysis Systems and covered in the Association for the Advancement of Medical Instrumentation standards.
Henry's LawA law of chemistry that states that the weight of a gas dissolved in a liquid is proportional to the pressure of the gas above the liquid.
HertzThe number of complete electromagnetic cycles or waves in one second of an electrical or electronic circuit.
HeterocyclicA type of organic compound in which the characteristic chemical groups are linked in a closed ring structure and in which one or more atoms in the ring is an element other than carbon, e.g. silica, sulfur, or nitrogen.
Heterotrophic MicroorganismsBacteria and other microorganisms that use organic matter synthesized by other organisms for energy and growth.
Heterotrophic Plate Count (HPC)A procedure for estimating the total number of live nonphotosynthetic bacteria in water.
HexametaphosphateA chemical that is used as a sequestering agent.
Higher Heating ValueThe total heat obtained from the combustion of a specified amount of fuel under perfect combustion conditions, and before subtracting the heat required to evaporate the water vapor formed during the combustion process. Also known as gross heating value.
High Frequency OzonationOperation of an ozone generator at frequencies equal to or greater than 1,000 cycles per second or 1,000 hertz.
High Line JumpersPipes or hoses connected to fire hydrants and laid on top of the ground to provide emergency water service for an isolated portion of a municipal distribution system.
High Performance Liquid Chromatography (HPLC)A general term applied to modern instrumental techniques adopted to greatly increase the scope and precision of the liquid chromatography analytical method.
High Pressure Steam BoilerBoiler that operates at a steam pressure over 15 psi and over 6 BHP.
High SaltingThe use of 15 pounds or more of salt to regenerate each cubic foot of cation resin.
High Temperature Water BoilerA boiler in which the maximum operating temperature of the water may reach temperatures in excess of 250°F and the operating pressure may exceed 160 psig.
High Voltage Electrode (Ozonation)The outlet post on the voltage transformer which produces more than 1,000 volts.
HOHVariation of the chemical formula for water.
HomogeneousHaving the same composition throughout.
Horizontal Return Tubular Boiler (HRT)A firetube boiler consisting of a horizontal shell set above a refractory brick-lined furnace.
Horizontal Split-Case PumpA pump that has a horizontally split pump casing where the top half of the pump casing can be lifted off for inspection and maintenance without disturbing the shaft, impeller, or bearings.
Horizontal Through StaysBraces that are installed in a firetube boiler to keep the upper portions of the tube sheets above the tubes from bulging outward due to the internal pressure.
Horsepower (HP)A unit of power equal to 33,000 foot-pounds of work done in 1 minute.
Hot Lime-Cation SofteningThe combination of two stage hot line softening process followed by hot cation exchange softening for complete hardness removal.
Hot Lime SofteningA partial softening method Which requires adding a lime slurry to water which is at about 212°F and then chemically precipitating and removing the calcium and magnesium, hardness via sedimentation and filtering.
Hot Process SofteningA term used to encompass several softening/clarifying process using lime, lime and soda ash, or lime and cation softening to treat water which is at or near the boiling point.
Hot Process Water SoftenerA pressure vessel that uses steam to heat makeup water by direct contact and uses chemical injection to precipitate the hardness out of the water.
Hot Water BoilerA boiler that generates hot water, not steam. The heated water produced by a hot water boiler is usually between approximately 170°F and 190°F
Hot WellA reservoir located at the bottom of a condenser where condensate collects.
HPCHeterotrophic Plate Count
HPLCHigh performance liquid chromatography.
HTHHigh test Hypochlorite. HTH is the trademark for a high test calcium hypochlorite product containing 70% available chlorine that is commercially available in both water - soluble granular and tablet forms.
Huddling Chamber Part on a safety valve that increases the area of the safety valve disc, thus increasing the total upward force, causing the valve to pop open.
Huddling RingAn adjustment in a safety valve that controls the degree to which the escaping steam is directed against the safety valve disc.
Human Exposure EvaluationA component of risk assessment that involves describing the nature and size of the population exposed to a substance and the magnitude and duration of their exposure.
Human Health RiskThe likelihood that a given exposure or series of exposures may have or will damage the health of individuals experiencing the exposures.
Humic AcidHumic Substances that are soluble in strong base solutions but insoluble in acidified water, and that affect water quality through exchange of species, such as cations or organic materials.
Humic SubstancesThe organic portion of soil that remains after prolonged microbial decomposition, and that is formed by the decay of leaves, wood, and other vegetable matter.
HumidificationThe process of increasing the water vapor and moisture content.
HuminHumic Substances that remain insoluble in both strong base solutions and in water.
HumusSEE Humic Substances.
HydrateA substance formed by combining water with a compound.
Hydrated LimeA strong alkali chemical, calcium hydroxide, obtained by treating lime with water in a heating producing reaction until the calcium oxide has been converted to calcium hydroxide.
HydrationThe chemical combination of water into another substance.
HydraulicReferring to water or other fluids in motion.
Hydraulic classificationThe rearrangement, during back washing, of ion exchange or other media particles according to size.
Hydraulic ConductivityThe capacity of rock or soil formations to transmit water to a pumping well.
Hydraulic Grade LineThe surface or profile of water flowing in an open channel or pipe flowing partially full.
Hydraulic GradientThe slope of the hydraulic grade line.
Hydraulic StagingMultiple passes of water between electrodes used in an electrodialysis or through a sequence of subsequent membranes or filters used in a reverse osmosis or filtration system to achieve further treatment.
HydrazineA liquid compound used as a strong reducing agent for transition metals and as an oxidation inhibitor for boiler feedwater and cooling water.
HydrocarbonAn organic compound containing only carbon and hydrogen.
Hydrochloric Acid (HCI)A water based solution of hydrogen chloride which is a strong, highly corrosive acid.
HydrocycloneThe basic form of most separators which act on the principle of centrifugal force and are used to remove sand and abrasives from well water.
Hydrogen BondThe week attraction between hydrogen atom carrying a partial positive charge and some other atom with a partial negative charge.
Hydrogen CycleA cation exchange cycle in which the cation medium is regenerated with acid and all cations in the water are removed by exchange with hydrogen ions.
Hydrogen PeroxideA strong disinfectant and oxidizing agent use mostly in dilute water based solutions.
Hydrogen SulfideA corrosive and flammable gas often found dissolved in well water and often accompanied by iron and low pH values. Naturally occurs from decaying material.
Hydrogeologic ConditionsConditions stemming from the interaction of ground water and the surrounding soil and rock.
HydrogeologistA person who studies and works with groundwater.
HydrogeologyA graph of that rate of runoff plotted against time for a point on a channel.
HydrologicThe complete circuit pursued by water in nature, including 1) the falling of precipitation. 2) the journey of fallen water over and through the earth's surface formations, 3) eventual evaporation of the water and its return to the atmosphere to again fall as precipitation.
HydrologyThe study of the occurrence, distribution and circulation of the natural waters of earth.
HydrolysateThe product of hydrolysis.
HydrolysisA Chemical process resulting from reactions with water; frequently used in reference to the breakdown of polymers.
HydropmetallurgyThe treatment of ores by wet processes as in leaching and accompanying operations, and the technology of separation or recovery of heavy or noble metals from liquid solutions by ion exchange methods.
HydrometerA device for measuring the density of specific gravity of liquids.
HydrophilicPertaining to a substance which readily absorbs water.
HydrophobicPertaining to a substance that does not readily absorb water.
Hydropneumatic SystemA system that uses both air and water in its operation.
Hydrostatic PressureThe pressure at a specific elevation exerted by a body of water at rest.
Hydrostatic TestA test in which the boiler is filled with approximately 70°F water and then pressurized to 1 1/2 times its MAWP. Any leaks are exposed by observing water drips.
HydroxideThe ion formed by an oxygen and a hydrogen atom.
Hydroxide AlkalinityAlkalinity caused by Hydroxyl ions.
HydroxylThe univalent group of radical, consisting of one atom of oxygen and one of hydrogen, that is characteristic of hydroxides such as sodium hydroxide, which is used as a regenerant for anion exchange resins.
Hygroscopic Having the characteristic of drawing moisture in from the atmosphere such a silica gel, calcium chloride or zinc chloride.
HyperfiltrationA water treatment process in which desalination of water is achieved by forcing sale solutions, under pressure, through a membrane which generally passes water more readily than salts.
HypochlorinationThe application of hypochlorite compounds to water for the purpose of disinfection.
HypochlorinatorsChlorine pumps, chemical feed pumps, or devices used to dispense chlorine solutions made from hypochlorites such as bleach or calcium hypochlorite into the water being treated.
HypopchloriteDominate reaction product of chlorine in water at pH greater than 8. Calcium and sodium hypochlorites are commonly used as disinfecting bleaching agents.
hypochlorous Acid (HOCI)The dominant reaction product of chlorine in water at pH less than 7.
IgnitionThe initiation of the combustion process.
Ignition ArchThe curved refractory brick arch directly above the location where green coal enters the furnace in a chain-grate stoker-fired boiler.
Imhoff ConeA clear, cone shaped container marked with graduations.
ImmiscibleNot capable of being mixed.
ImpellerThe rotating element found in a centrifugal pump that converts centrifugal force into pressure.
ImpermeableNot easily penetrated.
ImpingementThe condition in which flame continually strikes brickwork or boiler heating surfaces, causing localized overheating and soot deposits. The condition in which steam from a soot-blower element directly strikes the tube surfaces in a boiler, causing erosion of the tube metal.
ImplosionAn inward collapse from external pressure.
Impound WaterWater which is stored in an artificial man made basin or dammed ravine by diverting flowing streams or collecting rainfall runoff, as in a reservoir.
Incomplete CombustionA fire where the fuel is burned without the proper amount of oxygen, without enough mixing of fuel and oxygen, or at a temperature too low to allow satisfactory reaction of the fuel and oxygen.
Indicator1. A chemical material or solution which can be used to show the endpoint of a chemical reaction or chemical concentration. 2. A device which indicates the results of a measurement.
Induced DraftThe use of a fan to simulate the effect of a stack by drawing the combustion gases from the furnace and through the flue gas passages.
Induced InfiltrationThe recharging of a groundwater source by a flow of water into the groundwater reservoir as a result of lowered groundwater head caused by a previous withdrawal of groundwater.
Inert MediaSynthetic resin beads or water treatment material that are nonreactive.
InfiltrationThe movement of water into rocks or soil through interstitial pores, small cracks or crevices in the soil.
InfluentThe stream of water to be treated as if flows into any kind of water treatment unit or device, such as hard water into a softener or turbid water into a filter.
Inhibitor Any chemical substance that is added to a water supply, which interferes with a chemical reaction.
InjectorA motive fluid pump that uses the velocity of steam to draw water and pump into a boiler.
Inleakage AirAir that leaks into a furnace.
In-Line FiltrationThe addition of chemical coagulants directly to the filter inlet pipe. The chemicals are mixed by the flowing water.
In-line Steam SeparatorA cylindrically shaped vessel that is installed in a steam pipe to remove moisture droplets after the steam has left the boiler.
Inorganic MatterChemical substances which do not arise from the process of living growth, are composed of matter other than plant or animal matter, and don't contain hydrocarbons or compounds of basically carbon structure.
In-Parallel FlowA piping arrangement which directs separate streams through two or more units of a treatment system in a balanced manner, with equal flow to each devices, so that a higher total flow rate that that from a single unit can be achieved.
Input HorsepowerThe total power used in operating a pump and a motor.
Input SignalThe flow of control information provided to a control device.
In-Series FlowA piping arrangement in which the entire effluent flow from one unit of water treatment system in fed to a second succeeding unit.
In Situ CEMSA monitoring system that directly measures the concentration of a specific constituent in the stack, without conditioning, and provides a readout of that concentration for the boiler operator.
InstallationThe connecting or setting up and startup operations of any water treatment system.
In-Stream UsesWater uses that can be carried out without removing the water from its source, as in navigation and recreation.
InstrumentA device that measures, indicates, records, or controls a specific variable condition such as pressure, temperature, level, flow or pH.
InsulationMaterial used to cover hot piping or other hot surfaces to reduce heat losses and prevent thermal burns. Material used cover cold piping and other cold surfaces to prevent external corrosion due to condensation of moisture from the surrounding air.
Integrated Exposure AssessmentA summation over time, in all media, of the magnitude of exposure to a toxic chemical.
IntegratorA calculating device that totalizes the amount of flow over a specified time period.
Interfacethe surface which forms a common boundary between two spaces or two parts of matter, such as the surface boundary formed between oil and water. The term is often used to refer to the space between two different ion exchange resins in a mixed bed or to the resin surface at the regeneration grid in a mixed bed deionization system.
InterlockThe configuration of control devices such that two or more pieces of equipment cannot be operated independently of each other.
Intermittent FlowThe interrupted patterns of water usage which occurs in the home or in commercial business, opposed to the steady constant flow patterns common in industry, such as factories.
Intermittent PilotA pilot that is lit at the appropriate time to light the main burner and then stays on during the entire period that the burner is on.
Internally Fired Firetube BoilerA boiler with a furnace area surrounded by the pressure vessel.
Internal TreatmentThe addition of chemicals directly into the boiler water to control pitting, scale, and caustic embrittlement.
Interrupted PilotA pilot that is lit at the appropriate time to light the main burner and then extinguished as soon as the main burner is lit.
Inverse SolubilityThe tendency of certain impurities in water to crystallize and precipitate as the temperature of the boiler water increases.
IntersticesThe pores and other spaces which are not occupied by solid matter and may be found between filter medium particles, ion exchange resin beads, or other similar treatment media.
InvertThe lowest point of the channel inside a pile, conduit, or canal.
Inverted Bucket Steam TrapContains an upside-down steel cup, called a bucket, that is attached to a linkage that opens and closes a discharge valve as the cup rises and falls inside the trap.
IodineA nonmetallic element which is the heaviest and least reactive of the naturally occurring halogens.
IonAn atom or molecule having either a positive or negative electrical charge. Positively charged ions are referred to as cations and ions having a negative charge are termed anions.
Ion ExchangeIon exchange is based on the principle of electroneutrality, that is, charged species are stable only when they exist as balanced pairs of positive and negative charges. Ion exchange resins, the materials used to carry out the process of ion exchange, are particles which contain fixed charges on their surface. To maintain electroneutrality, each of these charges has an ion of equal and opposite charge held to it; these ions are called counter ions. The counter ions are mobile and can leave the fixed charge if some other counter ion is available to replace it. The replacement ion must be of the same charge as the initial counter ion in order to maintain electroneutrality. The initial counter ion is established by washing the resin with a concentrated solution of the desired counter ion. For example, the softener resins are cation exchangers containing carboxylic acids on their surfaces. If these resins are washed with strong NaCL solutions, the predominant cation in solution is Na+ and it will become the counter ion. In use the water will provide competing counter ions, such as Ca2+. Because of the preference of carboxylic acids for Ca2+ over Na+ in dilute solutions, the water will be depleted of Ca2+ in exchange for Na+ initially present.
Ion Exchange membraneA water tight and electrically conductive membrane which is either ion exchange resin cast in sheet form or powdered ion exchange resin laminated to a membrane fabric.
Ion ExchangerA permanent insoluble material which contains ions that will exchange reversibly with other ions in a surrounding solution.
Ionic ConcentrationA measure of the concentration of any ion in solution, usually expressed in moles per liter.
Ionic ConstantA measure in absolute units of the extent to which a chemical compound or substance in solution will dissociate into ions.
Ionic WeightThe weight of an ion as determined by the sum of the atomic weights of its components.
IonizationThe process in which a chemical combination breaks up into simpler electrically charged components called ions.
Iron (FE)A very common element often present in groundwater.
Iron BacteriaBacteria which thrive on iron and are able to actually use ferrous iron in their metabolic processes.
Iron Filter A pressure vessel used to remove iron from the raw water supply so that the iron will not interfere with the operation of other water treatment equipment or contribute to water-related problems in boilers.
Iron FoulingThe accumulation of iron on or within an ion exchange resin bed or filter medium in such amounts that the capacity of the medium is reduced.
Irreversible EffectEffects characterized by the inability of the body to partially or fully repair injury caused by toxic agent.
Jar TestA lab procedure that simulates a water treatment plants coagulation/flocculation units with differing chemical doses and also energy of rapid mix, energy of slow mix and settling time.
Jet PumpA combined centrifugal and ejector pump.
Jetted WellA shallow well constructed by a high velocity stream of water directed downward into the ground.
JoggingThe frequent starting and stopping of an electronic motor.
Kjeldahl NitrogenNitrogen in the form of organic proteins or their decomposition product ammonia, as measured by the Kjeldahl Method.
KYNARTrade name for polyvinylidene fluoride.
Laminar FlowThe movement of fluid in a particular direction in smooth,m continuous, non-turbulent parallel layers which do not mix with each other.
Langelier Saturation Index (LSI)The precipitation of calcium and magnesium carbonates in water purification systems is a serious cause of system failure. The insolubility of these compounds is a complex function of the pH of the water, the dissolved carbon dioxide content, the carbonate content, the presence of other salts and the temperature. The Langelier Saturation Index is a method of predicting whether or not carbonate deposits will form under given conditions. Reverse osmosis vendors may use the index in dtermining the maximum recovery and rejection rates that can be obtained from a reverse osmosis system before carbonate deposits will seriously reduce water quality and recovery. It should be noted that the utility of such determinations is limited to those situations in which a softener is not used as part of the pre-treatment scheme for reverse osmosis.
Large Public Water SystemA public water system that serves more than 50,000 persons.
Latern RingA spacer installed between of the rings of packing in a pump to allow cooling water to cool the packing and the pump shaft.
Lap JointA riveted joint with tow overlapping plates that are drilled through and riveted together at the edges.
LASLinear Alkylate Sulfonate.
LatencyTime from the first exposure to a chemical unit the appearance of a toxic effect.
Latent HeatThe Btu content of a substance that represents the heat absorbed or given up as it chages state between solid, liquid, and gas.
Laying UpThe procedure used to protect a boiler from internal corrosion if it is to be taken out of service for a longer than normal period.
LeachTo dissolve out by the action of a percolating liquid.
LeachateWater which has percolated or filtered through soil, filter medium or other substances containing soluble substances so that it now contains certain amounts of these substances in solution.
Leach FieldThe area where the effluent from a septic stank system is distributed by horizontal underground piping designed to aid in the process of natural leaching and percolation through the soil.
LeachingThe process by which soluble substances are dissolved and transported down through the soil by recharge.
Lead (Pb)A heavy metal that is hazardous to health if breathed or swallowed.
Lead Service LineA service line made of lead which connects the water main to the building inlet and any lead pigtail, goose-neck, or other fitting which is connected to such lead line.
LeakageThe presence in the effluent of the type of ions, present in the feedwater to be treated, which the ion exchange process was supposed to remove.
LegionellaOver 26 species of bacteria, which cause pneumonia like illness called "Legionnaires' Disease". They live in humidifiers, cooling tower water, and shower rooms. Infected by inhalation.
Level ControlA float device which sense changes in a measured variable and opens or closes a switch in response to that change.
Lift The condition where the level of the liquid to be pumped is below the elevation of the pump.
Lift and Turn ValveA master control valve for operating and manually regenerating softeners and filters.
LigamentThe portion of the drum wall between the tube holes.
Lighting OffThe initial ignition of the fuel.
LigniteVery young and very soft coal that has a high moisture content.
LimeA calcined chemical material, calcium oxide.
Lime ScaleHard water scale formed in pipes and vessels containing a high percentage of calcium carbonate or magnesium carbonate.
Lime SoapThe insoluble calcium and magnesium salts formed from fatty acid portion of soap when it combines with minerals in hard water, commonly referred to as soap curd.
Lime-Soda ProcessA process that uses lime and soda ash to soften water.
Lime SofteningA water treatment, often used by municipalities, for partial reduction of water hardness.
LimestoneA sedimentary rock composted mostly of calcium carbonate and usually some magnesium carbonate.
Limit StopsSeveral types of diaphragm valves which have adjustments used to control flow rates during various processes when brine is pumped in during batch regeneration of resin for portable ion exchange tanks.
Limulus amebocyte lysate (LAL)An extract from horseshoe crabs which forms a gel or clot in the presence of bacterial endotoxin and is widely used for quantitive measurements of these substances.
Linear Alkylate Sulfonate (LAS)Readily biodegradable form of alkylbenzene sulfonate surfactant.
LinearityHow closely an instrument measures actual values of a variable through its effective range.
Line DesuperheaterA device that automatically removes superheat from superheated steam so that the steam becomes saturated steam.
LiquificationThe transformation to the liquid state.
Liquid ChromatographyChromatography in which the mobile phase is a liquid. Separation of the sample components is accomplished via 3 modes 1) Liquid/Liquid in which the relative solubilities of sample components in two immiscible fluids create separation. 2) Liquid/Solid, in which the relative adsorption of sample components on a solid adsorptive medium surface creates separation. 3) molecular- size, in which separations are created because of the variation in effective molecular dimensions of the sample components in solution.
LiquorA solution of one or more chemical substances.
Live Steam Steam in its pure, invisible form.
Lobe PumpA rotary positive-displacement pump in which liquid being pumped fills the open spaces between the lobes of matched rotors and the pump housing.
Local ControlA control device that is installed directly on or very near the equipment on which it is being used.
LockoutThe use of locks, chains, and other physical restraints to prevent the operation of specific equipment.
Longitudinal FlowA flow pattern in which water travels from the bottom to top or vice versa, in either a cartridge type or loose media tank type filtration system.
LoopThe plumbing network designed to continuously circulate ultrapure grade water in high purity water systems between storage and disinfection modes to maintain microbiological cleanliness.
Loose Media FiltersThose filter units which have medium products positioned in a filter bed such that the individual medium grains or particles can be repositioned or lifted relative to each other with the flow of water or backwash water.
Loose MediumFilter or ion exchange media which can be expanded during backing washing and rinsing.
Lower Heating ValueThe quantity of heat remaining after subtracting the latent heat used in evaporating the water formed in the combustion of the hydrogen. Also known as net heating value.
Low Pressure BoilerBoilers that operate at a steam pressure of no more than 15 psi
Low Water Fuel Cutoff A device located slightly below the NOWL that turns off the boiler burner in the vent of low water.
Lug & Roller MethodA support method where steel lugs are welded or riveted to the front and rear of the boiler shell.
LyeSodium Hydroxide.
LyseTo undergo Lysis
LysimeterA device for measuring the percolation and drainage of water through soil.
LysisA process of disintegration or destruction of bacteria or microbiological cells by chemically breaking them down into their component parts.
Macroporous ResinA special grade of ion exchange resins which have large pores and higher resistance to oxidation and organic fouling.
Macroscopic OrganismsOrganisms big enough to be seen by the eye without the aid of a microscope.
MagnesiaMagnesium oxide that has been specially processed.
MagnesiumOne of the elements that make up the earth's crust as part of the many rock-forming minerals such as dolomite.
MagnetiteA black magnetic oxide of iron that is extremely dense and used as a coagulant and filter medium in water treatment.
Main Steam Outlet Lines Consist of the piping and valves that direct the steam from the boilers to the steam header.
Main Steam Stop ValveA gate valve in the main steam line between the boiler and the steam header used for isolating the steam side of a boiler that is to be out of service.
Main Trial for Ignition A period of about 5 sec to 10 sec for the flame scanner to sense the presence of flame from the main flame.
Makeup WaterWater used to replace condensate that is not returned to the boiler.
Makeup Water FeederAn automatic float-operated valve that feeds makeup water to a low-pressure heating boiler to replace condensate that has been lost from the system or water that has been lost in the form of steam leaks.
Makeup Water LineA city water pipe or well water pipe through which makeup water is added to a boiler.
MalleabilityThe ability of a material to deform permanently under compression without rupture.
ManganeseAn element sometimes found dissolved in groundwater, usually in combination with - but in lower concentrations than - iron.
Manganese DioxideA dark brown or gray black insoluble compound found in nature as pyrolusite, made synthetically, and used as an oxidizing agent in water treatment and as a starting material for permanganate compounds such as potassium permanganate.
Manganese Dioxide Coated PumiciteAn oxidizing catalyst medium used to remove iron and manganese.
Manganese GreensandGreensand which has been processed to incorporate the higher oxides of manganese into its pores and onto its surface.
Manganese Zeolitea synthetic gel zeolite which has been converted to the manganese form by the same process as manganese greensand and is used for the same treatment applications.
ManganiteA Form of manganese ore, consisting of manganic hydroxide, which is used in filters designed to reduce iron, manganese, and/or hydrogen sulfide and requires a very high backwash rate because of its very high density.
ManholeOpening found on the steam and water side of a boiler that is used for cleaning and inspection of the boiler.
ManifoldA large pipe to which a series of smaller pipes are connected.
ManometerAn instrument that measures draft by comparing pressure at two locations.
Manual Reset Valve:A safety shutoff valve that automatically closes by spring action when it's hold-open mechanism is electrically or pneumatically tripped by a connected interlock sensing a dangerous condition. It must be reopened by hand after the dangerous condition is rectified and the hold -open mechanism re-energized.
Marine SaltAn early chemical name for salt, partly because its source.
Master Control:Unit that receives the primary signal and relays signals to individual control units.
Material Safety Data Sheet:MSDS Printed material used to relay chemical hazard information from the manufacture importer or distributor to the user.
MAWP (Maximum Allowable Working Pressure)The highest pressure at which a boiler or pressure vessel may be safely operated.
Maximum Capacity:The maximum rating in pounds of steam that a boiler is designed to produce in 1 hour at a given pressure and temperature.
MCLMax Contaminant Level.
MCLGMax Contaminant Level Goal.
Mean Particle DiameterThe weighted average particle size, in millimeters, of the media particles or beads in a filter or ion exchange bed.
Measured VariableA characteristic or component part that is sensed and quantified by primary element or sensor.
Mechanical DraftDraft created by fans and blowers.
Mechanical FilterA pressure or gravity filter designed to physically separate and remove suspended solids from a liquid by mechanical means rather than by the chemical means.
Mechanical JointA flexible device that joins pipes or fittings together by the use of lugs and bolts.
Mechanical SealAn assembly installed around a pump shaft that prevents leakage of the pumped liquid along the shaft.
MediaA selected group of materials used in filters and filter devices to form barriers to the passage of certain solids or molecules which are suspended or dissolved in water.
MediumThe Singular form of media.
Medium Size Public Water SystemA public water system that serves greater than 3,300 and less than or equal to 50,000 persons.
MembranesMembranes are thin films made with structures designed to provide selective transport of solutes. In general, the selectivity of a membrane is based on its ability to pass or exclude species according to their size. Membrane structures may become homogeneous or asymmetric. Homogeneous membranes have structures which are uniform in cross-section, at least to a magnification of 100x. Most homogeneous membranes have been developed for micro-filtration and hemodialysis. Membranes reduce not only the flow of undesirable solutes, but also the flow of solvent. In order to minimize the reduction in solvent flow, asymmetric membranes have been developed. These membranes are made with asymmetric cross-sections, that is they consist of two parallel layers. The resistance to flow of the skin layer, which gives the membrane its filtration selectivity, is minimized by reducing its thickness. The resistance to flow of the thicker support layer, which provides structural strength, is minimized because of its open pore structure. These different layers may be made from the same material as in asymmetric cellulose acetate membranes or from different materials as in thin-film composite membranes. Membranes used in water treatment equipment are fabricated in two forms as flat sheets or as hollow fibers.
Membrane FiltrationA lab analytical technique fir the quantitative and qualitative analysis of bacterial or particulate matter in a water sample.
Membrane Watertube BoilerA boiler design in which rows of tubes are formed into solid panels through the use of welded steel strips that fill the spaces between each of the waterwall tubes.
Membrane WaterwallsWaterwalls that are formed into a solid airtight panel by welding a strip of steel between each of the waterwall tubes.
MeniscusThe curved top of a column of liquid, in a small tube.
Mercury SwitchA switch that uses the movement of mercury in a glass tube to start or stop electrical current flow in a circuit.
Mercury Vapor Ultraviolet LightThe UV light given off as the result of an electron flow through an ionized mercury vapor between electrodes in an UV lamp.
Mesh SizeMesh is the number of openings in a square inch of a screen or sieve.
Metering ControlAn approach to control where the flows of fuel and air are precisely measured by flow-measuring devices and then adjusted by the control system so as to always be in the correct proportions.
Metering Feedwater Regulating SystemA control that continually measures the boiler condition and adjust the feedwater control valve.
Metering PumpA small-capacity pump used to pump a closely measured amount of a liquid.
MethaneA colorless, odorless, flammable gas consisting of hydrocarbon.
Methyl OrangeAn acid base indicator that turns red in a solution below three on the pH scale and yellow between pH of 4.4 and 7.0.
Methyl Orange AlkalinityA measure of the total alkalinity in a water sample.
Methyl Tertiary Butyl Ether (MTBE)Incorporated in gasoline mixtures as an antiknock replacement for aromatics and as an oxygenator to reduce carbon monoxide emissions.
mg/LMilligrams per Liter.
Microbial GrowthThe activity and growth of microorganisms such as bacteria, algae, diatoms, plankton, and fungi.
Microbiologically Unsafe WaterWater that is 1) known to contain disease. 2) Shows a positive test for an indicator organism such as coliform, fecal coliform or E coli Bacteria. 3) is determined unsafe by health or regulatory agency.
MicroporousIn the context of water purification, membranes having an average pore size, which is between 0.1 and 1.0 microns in diameter.
Microporous ResinIon exchange resin with low porosity, usually polystyrene cross linked typically with about 3% divinylbenezene.
Microsiemensone-Millionth of a siemens.
Midpoint DistributorThe lateral distribution system located at the interface where stratified anion and cation beds in a mixed bed ion exchange deionizer meet.
Mineral1. An inorganic substance which occurs naturally in the earth and has composition that can be expressed as a chemical formula and set of characteristics common to all minerals. 2. Term used in the water treatment industry to refer to a naturally occurring inorganic cation exchangers formerly used in water softeners.
Mineral Acidity Acidity in water due to the presence of strong inorganic acids such as hydrochloric, nitric, and sulfuric acids as opposed to weak acidity due to such acids as carbonic acid and acetic acid.
Mineral Free WaterWater produced by either distillation or deionization.
MineralizationThe microbial conversion of an element from an organic to an inorganic state.
Mineral SaltA chemical compound formed by the combination of mineral acid and a base.
Mineral WaterWater which is naturally or artificially impregnated with mineral salts or gases.
Miner's SaltAnother name for mined rock salt.
Miniature BoilerA small boiler that meets several criteria for dimensions and capacity.
MiscibleAble to be mixed together or dissolved into each other to produce a homogeneous substance.
Mixed BedThe intermix of two or more filter or ion exchange products in the same vessel during a service run.
Mixed LiquorA mixture of activated sludge and waters containing organic matter undergoing activated sludge treatment in the aeration tank of a waste water treatment system.
Mixed MediaThe use of two or more media products in a single filtration loose media bed where the products are intermixed, rather than in stratified layers.
Modulating Feedwater Regulating System Continually adjusts the position of a feedwater regulating valve as needed in an effort to maintain a constant boiler water level by matching the position of the valve to the change in the boiler water level.
Modulating MotorA small electric motor and reduction gear assembly enclosed in a metal box, used for positioning a valve and/or damper.
Modulating Pressure ControlA control device that regulates the burner for a higher or lower fuel-burning rate, depending on the steam pressure in the boiler.
ModuleThe membrane element and its housing in a reverse osmosis unit.
MonelTrade name for a series of corrosion resistant alloys made of nickel and copper.
MonitoringMeasuring concentrations of substances in environmental media or in human or other biological tissues.
Monitoring WellWells used to collect groundwater samples for analysis to determine the amount, type and spread of contaminants in groundwater.
MonoBedA product trade name for a fully regenerated ion exchange mixed bed.
MonochromaticConsisting of radiation or rays, such an UV,of a single wavelength or of a very small range of wavelengths.
Monovalent IonA cation or anion having a single deficit or extra electron.
Most Probable Number (MPN) Term indicating the number of organisms in a sample water which, according to statistical theory, would most likely produce the results observed in the multiple tube fermentation bacteriological tests.
Motive Fluid PumpA pump that uses the force of a secondary fluid to pump the primary fluid.
Mother LiquorResidual brine's, containing chiefly calcium and magnesium chlorides, obtained after the salt has been crystallized and removed from solution.
MotileCapable of self propelled movement.
Motive FlowThe water flow rate through a venturi injector that provides the suction at the injection port of the injector to induce the flow of another liquid.
Motor EfficiencyThe ratio of energy delivered by a motor to the energy supplied to it during a fixed period or cycle.
MudballsMaterial that is round in shape and varies from pea size to 2 or more inches in diameter. Formed in filters and gradually increase in size when not removed by backwashing.
Multifunctional MediumA single filter or ion exchange medium used to treat water for the removal of more than one constituent.
Multilayered BedA media bed in which more then one filter or ion exchange medium is used in the same vessel with each medium retaining its stratified position as a layer - even after specified backwashing is performed- due to differences in media densities.
Multiple-Pass BoilerA boiler equipped with one or more baffles that direct the flow of combustion gases such that the gases pass over two or more successive sections of heating surfaces.
Multiport ValveA master control valve used in a filter, deionizer or water softener to control all necessary steps in the regeneration process or the backwashing and rinse down filters.
Multistage PumpA pump that has more then one impeller.
Municipal SofteningA hardness reduction process performed at municipal central treatment plants to deliver water in the range of 5 to 12 grains per gallon total hardness.
Municipal WaterWater that has been processed at a central plant to make it potable or safe to drink and which is then distributed to homes and businesses via water mains.
MushingMushing of water softener salt occurs when salt pellets break down into their crystallized form.
NAICSNorth American Industry Classification System.
NanofiltrationA membrane treatment process which falls between reverse osmosis and ultrafiltration on the filtration spectrum.
Natural DraftDraft that occurs without mechanical aid.
Naturally soft WaterGround, surface, or rain water sufficiently free of calcium and magnesium salts so that no curd will form when soap is used and no calcium based or magnesium base scale will form when the water is heated.
Needle ValveA valve that is very similar to a globe valve, except that the opening/closing mechanism on the end of the valve stem is usually a sharp tapered cone that seats in a matching cone-shaped seat.
Negative-Suction Pump InstallationAny installation where the pump must draw (lift) liquid up from a source below the pump.
NephelometricA means of measuring turbidity in a sample by using an instrument called a nephelometer.
NeutralMidpoint reading on pH scale.
NeutraliteA trade name for a calcite mineral product which is used in loose media bed filters to modify the pH of low pH water sources.
NeutralizationThe addition of either an acid to a base or a base to an acid to produce a more nearly neutral solution.
Neutralizing AmineA chemical that neutralizes the pH of the condensate.
NitrateAn anion comprised of one nitrogen atom and three oxygen atoms. Nitrates are considered toxic in hemodialysis water and are also harmful to infants when consumed orally.
NitrificationThe biochemical transformation of ammonium nitrogen to nitrate nitrogen.
Nitrification InhibitorA chemical that slows down the conversion of ammonium to nitrate nitrogen.
Nitrogen FixationThe biological or chemical process by which elemental nitrogen, from the air, is converted to organic or available nitrogen.
NitrogenousA term used to describe chemical compounds containing nitrogen in combined forms.
Noble (Metal)Chemically inactive. Not reactive.
Nominal Filter RatingFilter rating indication the approximate size particle, the majority of which will not pass through the filter.
Nominal Pipe SizeThe designation of a water pipe base on the approximate size of its inside diameter.
Noncarbonate HardnessHardness caused by calcium or magnesium existing in compound form with chloride, sulfate and nitrate anions rather than with the more common carbonate or bicarbonate anions.
Noncondensable GasA gas that does not change into a liquid when its temperature is reduced to room temperature.
Nondestructive Testing (NDT)A method of determining the condition of components without causing damage and impairing their future usefulness.
Nondrainable Superheatera superheater that does not have condensate drain connections.
Nonhardening SaltSalt containing amounts of agents such as calcium or magnesium chloride which become soft or liquid by attracting and absorbing moisture from the air and preventing salt caking and bridging.
Non-Permit Confined SpaceA confined space that does not contain or with respect to atmospheric hazards, have the potential to contain any hazards capable of causing death or serious physical harm.
NonpotableWater that contains objectionable pollution's, contamination, minerals or infective agents and is considered unsafe.
Non-return Valve A combination shutoff valve and check valve that allows steam to pass out of the boiler, but not return into the boiler.
Nonrising Stem ValveA valve that has a disc in the valve that threads up onto the stem as the stem is turned, and the stem does not back out of the valve.
Normal Flow FiltrationThe flow of the entire feedwater stream in one direction directly through the filter media.
Normal Operating Water Level (NOWL)Water level carried in the boiler gauge glass during normal operation.
Normal SolutionA normal solution contains one gram equivalent weight of dissolved substance in a liter of solution.
N0xAn abbreviation used to represent a group of gases that are produced as a result of the chemical reaction between nitrogen and oxygen at high temperatures.
OcclusionAn absorption process by which one substance is taken in and retained in the interior rather than on the external surface of another, sometimes occurring by coprecipitation.
Odor ThresholdThe minimum odor of water sample that can just be detected after successive dilutions with odorless water.
Off GasAir or vapor given off or expelled as a byproduct or result of an operation or treatment process.
Off/Low/High ControlAn approach to steam pressure control in which a burner is either OFF or it is operating with a lower firing rate or with a high firing rate.
OffsetThe difference between the actual value and the desired value; characteristic of proportional controllers that do not incorporate reset action.
Offstream UseWater withdrawn from surface or groundwater sources for use at another place.
Oil of VitriolAn old and now obsolete term once used for sulfuric acid.
OleophilicHaving a strong affinity for oil and thereby exhibiting the characteristic of adsorbing oily type substances.
OlephobicHaving a strong aversion for oil and thereby exhibiting the characteristic of repelling oily type substances.
OleumThe Latin word for oil.
Olfactory FatigueA condition in which a person's nose, after exposure to certain odors, is no longer able to detect odor.
Oligo-Dynamic ActionThe bacteriostatic action exerted by very small amounts of heavy metals such as copper, silver and zine which deactivates bacteria and creates a hostile environment for the growth of bacterial colonies.
ON/Off Control An approach to steam pressure control in which a burner is either ON or OFF.
ON/OFF Feedwater Regulating SystemA Level Control system that uses a water level-detecting device to turn the feedwater pump ON when the boiler water level drops to a preset point, and turn the pump OFF when the water level has risen to an upper setting.
ON/OFF/ with modulation controlAn approach to steam pressure control in which the amount of flame is changed to a degree that is proportional to the need and includes the function of automatically shutting down or starting the burner when necessary.
OpacimeterAn automatic indicator that measures the amount of light blocked by the smoke and ash going up the stack.
OpacityThe capacity of matter to block the passage of light or other radiant energy such as heat.
Open Heat ExchangerA heating unit in which steam or another heating medium and the fluid being heated come into direct contact.
Open ImpellerAn impeller that has vanes that are not enclosed or supported by a shroud on either side.
Operating CycleThe complete filtration process consisting of filter service, backwash and rinse, and return to service.
Operating PressureThe manufacturer's specified range of pressure expressed in pounds per square inch within which a water processing device or water system is a designed to function.
Operating Range The range within which a controlled variable is maintained by a control device.
Operating TemperatureThe manufacturer's recommended feedwater or inlet water temperature for a water treatment system.
Organic Having the characteristics of, or being derived from, a living organisms, plant, or animal.
Organic IronIron that is bound or complexed with organic compounds, such as a naturally occurring humic and fulvic acids.
Orifice PlateA plate having a concentric circular hole of a precise size that is installed in a pipeline. The pressure difference that occurs across the hole is used for measuring the flow of fluid through the pipeline.
Orsat AnalyzerA flue gas analyzer that measures the percentages of carbon dioxide, carbon monoxide and oxygen in the gases.
ORP (Oxidation - Reduction Potential)The electrical potential required to transfer electrons from one compound or element to another.
OSHA The occupational Safety and Health Administration.
OsmosisThe natural tendency for water to spontaneously pass through a semipermeable membrane separating two solutions of different concentrations.
Osmotic PressureWhen a solution, such as saltwater, is separated from pure water by a membrane which is impermeable to the salt, a flow of water will occur from the pure water to the salt solution. The driving force for this flow is called the osmotic pressure and its magnitude depends on the number of salt particles in the solution. Note that the osmotic pressure depends on the number of particles and not on the total mass on particles. For example, 1 g/L of a small solute such as sodium chloride will exert a greater osmotic pressure than 1 g/L of a large solute, such as protein. For water to flow from the salt solution to the pure water, the solution must be exposed to a hydrostatic pressure greater than its osmotic pressure. This is the principle of reverse osmosis.
Osmotic StabilityAn expression of the ability of an ion exchange resin to resist physical degradation due to volume changes imposed by repeated applications of dilute and concentrated solutions.
"O" Style Watertube Boiler A watertube boiler design with a top steam and water drum and a bottom mud drum that are interconnected by banks of symmetrical tubes in an "O" shape.
OrthophosphateA salt that contains phosphorus.
OrthotolidineIs a colorimetric indicator of chlorine residual.
Output SignalThe flow of control information leaving a control device and traveling to another device.
Outside Stem & Yoke Valve (OS&Y)A valve containing a stem that screws out from the center of the valve hand wheel when the valve is opened.
Overall Efficiency PumpThe combined efficiency of a pump and motor together.
OverdraftThe pumping of water from a groundwater basin or aquifer in excess of the supply flowing into the basin.
Overfire AirThe high-velocity secondary air that creates turbulence in the flue gases above the top of the fuel bed. This helps mix oxygen with the combustibles in the flue gases for greater efficiency.
OverfiringForcing a boiler beyond its designed steam-producing capacity.
Overflow RateOne of the guidelines for the design of settling tanks and clarifiers in treatment plants.
Overhead Suspension MethodA support method where the boiler is suspended from an overhead steel beam structure by sling members.
OverrunOperating a filter or ion exchange system beyond its predetermined exhaustion point.
OverturnThe almost spontaneous mixing of all layers of water in a reservoir or lake when the water temperature becomes similar from top to bottom.
OxidantsChemicals which provide oxygen and accept and electron in an oxidation reduction reaction. Free chlorine and chloramines are oxidants which are widely used for disinfection.
OxidationThe process in which a molecule, atom, or ion loses electrons to an oxidant.
OxidizeTo increase a molecule or ion in a positive valence.
Oxidizing AgentA chemical substance that gains electrons and brings about the oxidation of other substances in chemical oxidation and reduction reactions.
Oxidizing FilterA type of filter used to change the valence state of dissolved molecules, making the insoluble and therefore, filterable.
Oxyacetylene WeldingA welding process that uses acetylene which is combined with oxygen to produce a flame with a temperature over 6,000°F.
OxygenateTo impregnate or combine with oxygen such as the forced draft step in aeration.
Oxygen Trim SystemAn automation Control System that makes fine adjustments in the amount of combustion air used in order to minimize excess air.
Oxygen ScavengerA chemical that reacts with any oxygen remaining in the boiler feedwater and changes it into a form that does not cause corrosion.
OzonationThe process of feeding ozone into a water supply for the purpose of decolorization, deodorization, disinfection, or oxidation.
OzoneAn extremely active oxidizing agent who consists of three oxygen atoms. It can be formed by the action of a high voltage electrical field on oxygen gas or ambient air with an oxygen content.
Ozone DestructionThe step by which a component unit of an ozonation system destroys all or some of the ozone present in the off gas being vented.
Ozone EnrichmentA step in the ozonation process in which more ozone is added to a gas which previously contained ozone.
Ozone Half LifeThe period of time required for 50% of a give quantity of ozone to decompose at a specific temperature and pressure.
OzonideA compound which occurs as a byproduct of ozonation.
OzonolysisThe oxidation of an organic material by ozone.
OzonosphereA region in the upper atmosphere containing a relatively high concentration of ozone which absorbs certain wavelengths of solar ultraviolet radiation that are not screened out by other substances in the atmosphere.
Package BoilerA boiler that is supplied from the manufacture complete with controls, burner(s), and appliances attached.
Packed BedA bed of filter or ion exchange medium which is completely retained so that no bed expansion can occur and no backwash step is used to reclassify the filter or resin.
Packed Tower AerationThe method of treating water to remove volatile organic chemical contaminants.
Packing Gland Holds packing or seals in place on valves and pumps to minimize leakage.
PalatableWater at a desirable temperature that is free from objectionable tastes, odors, colors, and turbidity.
ParallelIn water purification, an arrangement of equipment in a side-by-side configuration such that water flow is divided and passes through one or both of these branches.
Parallel Positioning ControlAn approach to steam pressure control in which a master device or controller sense the steam header pressure and modulates the fuel feed and combustion airflow independently to vary the boilers firing rate while maintaining a correct air-fuel ratio.
Parshall FlumeA device used to measure the flow in an open channel.
ParticleA very tiny, separate subdivision of matter.
Particle CountThe results of a microscopic examination of treated water with a special particle counter which classifies suspended particles by number and size.
Particle FiltrationFiltration of particles in the size range of two microns or larger in diameter.
Particle SizeAs used in water industry standards, the term refers to the size, expression in microns, of a particle suspended in water as determined by the smallest dimension.
ParticulateFine ash particles from a burner that ultimately settle back to earth.
Part Per Billion (ppb)The concentration of a solution equal to one part of a chemical in one billion parts of the solution.
Part Per Million (ppm)The concentration of a solution equal to one part of a chemical in one million parts of the solution.
Passes The number of times the gases of combustion flow the length of the boiler as they transfer heat to the water.
PathogensMicroorganisms that can cause disease in other organisms or in humans, animals, and plants.
Peak Operating FlowThe maximum rate of flow under which a treatment unit is designed to properly function and produce a certain quality product water.
Peracetic AcidA strong oxidizing liquid used in a proprietary 1% solution with hydrogen peroxide as an effective sanitizer and disinfectant for both cellulosic and thin film composite reverse osmosis membranes.
Percent RecoveryThe percentage of feedwater which becomes product water.
Percent RejectionThe percentage of TDS in the feedwater that is prevented from passing the membrane with the permeate.
Percent SaturationThe amount of a substance that is dissolved in a solution compared with the amount that could be dissolved in the solution, expressed as a percent.
Perfect Combustion A fire where the fuel is burned with precisely the right quantity of oxygen so that no fuel or oxygen remains and the maximum possible heat results.
Percolating WaterWater that passes through soil or rocks under the force of gravity.
PercolationThe slow seepage of water into and through the ground.
Performance Evaluation SampleA reference sample provided to a lab for the purpose of demonstrating that the lab can successfully analyze the samples within limits specified by the Agency the true value of the concentration of the reference material is unknown to the lab at the time of the analysis.
Peristaltic PumpA self priming pump that achieves pumping action by moving a system of rollers against a flexible tube.
Permanent HardnessA type of hardness that can be reduced only by the use of chemicals or distillation.
PermeabilityThe ability of a body, such as a reverse osmosis or ultrafiltration membrane, to pass a liquid under pressure or to pass ions under the influence of an electric current as an ion exchange membrane in electrodialysis.
PermeateTo penetrate and pass through, as water penetrates and passes through soil and other porous materials.
Permissible DoseThe dose of a chemical that may be received by an individual without the expectation of a significantly harmful result.
PermissiveA process condition that must be met before a certain action may be taken.
PermselectrivityThe ability of a semipermeable membrane to also be an ion exchanger and to allow selective passage of anions or cations under the influence of an electric current.
Permit-Required Confined SpaceA confined space that has specific health and safety hazards associated with it.
Permutite ProcessAn older term for the cation exchange method of water softening.
PeroxideAny compound containing the two oxygen atoms united together into a bivalent -O-O group.
Peroxone ProcessA water treatment process in which ozone is exposed to ultraviolet light or hydrogen peroxide as it is being applied to the water.
PersistenceThe resistance to degradation as measured by the period of time required for complete decomposition of material.
Personal Protective EquipmentAny device worn by a boiler operator to prevent injury.
Petroleum DerivativesChemicals formed when gasoline breaks down in contact with groundwater.
PEXCrossed Linked Polyethylene.
pHWater can dissociate into two ions: hydrogen (H+) and hydroxyl (OH). These ions can also be added to water in combination with other oppositely charged ions. Thus, a solution of hydrochloric acid added to water provides both H+ and chloride anion, Cl-. The concentration of H+ in the water is a measure of the waters acidity and the concentration of OH- a measure of its alkalinity. pH values range from 1 to 14. A pH of 7 is considered neutral. Lower values of pH indicate acidic conditions and higher pH values indicate alkaline conditions.
Pharmaceutical Grade WaterThe collective term for 6 types of water as defined by US Pharmacopeia; 1) Purified Water, 2) Water for infection, 3) Bacteriostatic Water for injection, 4) Sterile water for inhalation, 5) Sterile water for injection, and 6) Sterile water for irrigation.
PharmacokineticsThe dynamic behavior of chemicals inside biological systems.
PhaseA term used in general chemistry to refer to a particular homogeneous form of substance which might exist in other forms or phases.
PhenolphthaleinAn acid based indicator which has no color in acid solutions but turns pink to red as the solution becomes alkaline.
PhosphateA chemical that causes hardness in boiler water to precipitate and settle out as a heavy sludge.
PhosphonateAn organic phosphate that provides multiple functions in water treatment.
PhosphorusA nonmetallic element which is essential to life.
Physical StabilityA measure of the ability of an ion exchanger or filter medium to resist breakdown caused by the physical forces such as crushing, attrition, or high temperatures to which it is a subjected during use.
pi (π)The ratio of the circumference of a circle to its diameter. The circumference of a circle is always equal to the diameter multiplied by pi.
PilotUsed to ignite fuel at the proper time in a firing cycle.
Pilot Trial For Ignition or PTFIA period of about 5 sec to 10 sec for the flame scanner to sense the presence of flame from the pilot.
Piston ValveA valve that contains a finely machined piston that moves up or down in the interior of a cylindrical steel cage.
Plant MasterThe master controller that calculates and distributes the steam production requirements to two or more boiler when they are used to maintain the pressure in a common steam header, such as when the boilers are installed in battery.
Plug FlowA flow pattern in which the water being processed passes through the medium in a piston like fashion instead of in turbulent or mixed flow patterns such as are found in other processes like ultraviolet light disinfection and electrodialysis.
Plug Valve A valve that is similar to a ball valve, except that a plug valve contains a semi-conical plug through which the flow passes.
PneumaticPowered or moved by air pressure or compressed air.
Pneumatic TankA pressurized holding tank which is part of a closed water system and is used to create a steady flow or water and avoid water surges created by the pump kicking on and off.
PneumercatorAn air actuated liquid level measuring device.
POEPoint of Entry.
Point of Entry (POE) TreatmentFull service water treatment applied to the water entering a house or building for the purpose of reducing contaminants in the water distributed throughout the house or building.
Point of Use (POU) Treatment Water treatment applied to a single trap used for the purpose of reducing contaminants in water at the one outlet.
PolarizeTo disrupt the corrosion process by developing a barrier on an anodic or cathodic surface.
Pole ShaderA copper bar circling the laminated iron core inside the coil of a magnetic starter.
PolisherA treatment stage placed at the end of other treatment to bring the water to a more highly conditioned and more perfect state.
Polishing FilterA filter installed for use after the primary water treatment stage, to remove any traces of undesirable matter or to polish the water.
PollutantA contaminant existing at a concentration high enough to endanger the environment or the public health or to be otherwise objectionable.
PolymerA chemical formed by the union of many monomers.
Polymer DispersantA synthetic compound that prevents scale deposits on boiler surfaces.
PolyamideA synthetic polymer of nylon family used in the fabrication of reverse osmosis and ultrafiltration membranes.
PolypropyleneA thermoplastic polymer of propylene resembling polyethylene, and used for making molds and extruded plastic products such as water pipe, tubing and fittings.
PolystyrenePolymerized styrene. forms the skeletal structure of most common ion exchange resin beads.
PolysulfoneA synthetic polymer used in the fabrication of reverse osmosis and ultrafiltration membranes which are characterized by extreme thermal stability and chemical resistance.
Polyvalent IonA cation or anion having a multiple electrical charge.
Polyvinyl Chloride (PVC)A thermoplastic material produced by the polymerization of vinyl chloride. Used extensively in the U.S. for piping, food packaging and injection molded plastic parts. PVC is the most common pipe material used in the U.S. for dialysis applications.
Polyvinylidene Fluoride (PVDF) A thermoplastic fluorocarbon polymer that can be used for infection molded or extruded products.
Popping PressureA predetermined pressure at which a safety valve opens and remains open until the pressure drops.
Pop-Type Safety ValveA spring-loaded valve that opens fully and instantly and causes a definite, measured drop in pressure before closing.
Portable Exchange (PE) TanksTanks containing up to 2 cubic feet of ion exchanger products or filter media which are rented to homeowners or business clients with the beds fully regenerated and ready to use.
Positioning ControlsAn approach to control in which a master device, or controller, and sense the pressure in the steam header and uses compressed air to modulate power units, or actuators which in turn position control linkages.
Positive-Displacement PumpA pump that moves the same amount of liquid with every stroke or rotation.
Positive DraftThe condition wherein the pressure inside the boiler furnace becomes greater than the pressure outside the furnace.
Positive-Suction Pump InstallationAny installation where the pump receives liquid on the suction side from a source above the pump-that is under head.
PostchlorinationThe application of chlorine to a water following other water treatment processes.
Potable Drinking WaterA Water supply which meets USEPA and/or state water quality standards and that is considered safe and fit for hum consumption.
Potassium Chloride (KCI)A colorless potassium salt which can be used as a regeneration of cation exchange water softeners.
Potassium PermaganateAn oxidizing agent commonly used for the regeneration of manganese greensand iron filters and occasionally used as disinfectant. This material can cause significant damage to membrane elements.
PotencyAmount of material necessary to produce a given level of a deleterious effect.
PotentiationThe effect of one chemical to increase the effect of another chemical.
Potentiometric SurfaceThe level to which water will rise in cased wells or other cased excavations into aquifers, measured as feet above mean sea level.
POUPoint of use.
Pour PointThe lowest temperature at which a liquid will flow from one container to another.
PowerThe rate at which work is done.
PrechlorinationThe application of chlorine to a water supply prior to other water treatment processes which may follow.
PrecisionThe ability of an instrument to measure a process variable and to repeatedly obtain the same results.
PrecoatThe application, usually by flurry, of a very fine granular filter medium.
Predictive MaintenanceA study of the history of the plant components and determination of the expected service life of critical components.
Preplumbed InstallationAn installation which allows domestic water treatment equipment to be easily installed because the necessary bypass and valves are already in place.
PrescriptiveWater rights which are acquired by diverting water and putting it to use in accordance with specified procedures.
Pressure ControlA switch which operates on changes in pressure.
Pressure DifferentialThe difference in the pressure between two points in a water system.
Pressure DropExpenditure of a certain amount of energy is required for a fluid flow through any channel such as pipe, particle bed or membrane. The pressure at any point is a measure of the energy content of the fluid at that point. Since some of this energy is expended in flowing to a second point downstream, the pressure at the downstream point is less than at the original point. The amount of energy expended and hence the decrease in pressure (or pressure drop), is dependent on the flow rate and viscosity of the fluid and or PSI or in the SI system kPa (kilopascals) or Kg/cm2. Pressure drop is sometimes referred to colloquially as "delta-P".
Pressure HeadThe vertical distance equal to the pressure at a specific point.
Pressure Reducing Valve (PRV)A valve that is designed to reduce the pressure of a fluid flowing through a pipe to a desired lower pressure, and constantly maintain this desired pressure downstream of the valve.
PretreatmentThe water treatment process that occur before the water enters the boiler.
Preventive MaintenanceThe practice of performing maintenance activities on a piece of equipment to prevent breakdowns from normal or predictable causes.
Primary AirThe initial volume of air that enters the furnace with the fuel for most of the combustion process.
Primary ControlA flame safeguard control that consist of the relays and electronics required to safely start, run and stop the burner under orders from an external control device such as a pressure switch.
Primary Element or SensorA device that measures the process variable and produces a usable output in the form of a mechanical movement, electrical output, or instrument air pressure output.
Primary Treatment The first major treatment in a waste water treatment works, consisting usually of sedimentation.
PrimingA severe form of carryover in which large slugs of water leave the boiler with the steam.
Priming PumpA vacuum pump that ejects air from the suction line of a larger negative-suction pump installation.
Prior AppropriationA doctrine of water law that allocates the right to use water on a first come, first serve basis.
Private OrganizationAn organization that develops standards from an accumulation of knowledge and experience with materials, methods and practices.
ProcessThe collection of equipment and actions required to accomplish a desired objective.
Process VariableThe condition that is being controlled. It is the condition that may vary within the process.
Product WaterThe purified water stream from purification equipment, such as reverse osmosis units and ultrafilters.
Programmable Logic Controller (PLC)A small computer that maybe configured, or programmed, to control a wide variety of processes.
Programming ControlA flame safe guard control that consists of all the components needed to safely perform a desired sequence of operations for a larger commercial or industrial burner.
Proof Of Closure Switch (POC)A sensor that detects the position of a valve to ensure that the valve closes properly.
Proximate AnalysisThe percentages of moisture, volatile, fixed carbon, ash and often the percentage of sulfur and the British Thermal Unit (BTU) content of a coal sample.
PSIPounds per square inch.
PSIGPounds per square inch gauge. Pressure measured with respect to that of the atmosphere.
Pulverized CoalCoal that has been ground to the consistency of talcum powder.
PulverizerA mill that grinds coal to a very fine powder.
Pump ControllerStarts and stops a feedwater pump, depending on the water level in the boiler.
Pumping StationMechanical devices installed in sewer or water systems or other liquid carrying pipelines that move the liquids to a higher level.
Purge PeriodA short period of time, typically 30 sec to about 2 min, when air is blown through the furnace area to ensure that no volatile fuel vapors are present prior to the pilot being lit.
Push-Nipple Cast Iron Sectional BoilerContains hollow cast iron sections joined with tapered nipples and pulled tightly together with tie rods or bolts.
PyriteA common mineral consisting of iron disulfide.
Pyrite Trap A compartment or box in the pulverizer that catches nuggets of pyrite as they are separated from coal.
Pyrogenic ReactionsA physical response to the presence of endotoxin in the blood stream, which is characterized by fever and occasionally, chills or shaking rigors.
PyrometerAn instrument that measures temperatures above the temperature range of mercury thermometers.
Qualification TestTests and verifications performed to validate water treatment equipment conformance to a specific standard.
Quality Of SteamThe dryness of them steam.
Quartz JacketA clear, pure fused quartz tube used to protect the high intensity ultraviolet lamps in ultraviolet systems.
Quick-Closing ValveA valve that requires a one-quarter turn to be fully open or closed.
Quick-Drain TestA test that empties the float chamber or electric probe chamber while that burner is firing in order to test the low water fuel cutoff switch.
QuicklimeLimestone that has been thoroughly dried.
Quick-Opening Valve A valve that requires only a 90° change in the position of a lever arm to move the valve from fully closed to fully open.
Radial FlowThe flow pattern in which water flows from the outside of a filter element to the center core.
Radial to ImpellerPerpendicular to the impeller shaft.
Radiant SuperheaterA superheater that is directly exposed to the radiant heat of the furnace.
RadonA colorless, odorless, short lived radioactive gas which is produced by decay of the uranium series and is soluble in water.
Ramming MaterialsPlastic refractory materials that are rammed into place using heavy bars and other tools.
RankThe hardness of coal.
Ranney CollectorThis water collector is constructed as a dug well from 12 to 16 feet in diameter that has been sunk as a caisson near the bank of a river or lake.
Rated CapacityThe manufacturers rated service cycle statement regarding the expected number of days the equipment will be in service or the expected number of gallons of treated water delivered between servicing of the media.
Rated Service FlowThe manufacturer specified maximum and minimum flow rates at which a particular piece of water treatment equipment will continuously produce the desired quality of water.
Rate Of CombustionThe amount of fuel that is being burned in the furnace per unit of time.
Raw WaterWater, usually from wells, which has had no previous treatment and is entering a water processing system.
Reaction TankA tank or reservoir in which water treatment chemicals are allowed residence time to react with contaminants in the water.
ReaerationThe introduction of air through forced air diffusers into the lower layers of the reservoir.
ReagentA chemical used in a water treatment test to show the presence of a specific substance, such as hardness.
Rear HeaderFound on straight-tube watertube boilers. Connected to front header by water tubes.
RecarbonationA process in which carbon dioxide in bubbled into the water being treated to lower the pH.
RechargeProcess by which rainwater seeps into the groundwater system.
Reciprocating PumpA displacement pump that uses a reciprocating piston or diaphragm to repeatedly displace fluid from a cylinder or chamber.
Recirculation LineA line that provides a minimum flow through a pump to prevent overheating.
Reclaimed BrineThe portion of a previously used brine solution used to regenerate a batch of cation resin for portable exchange softener tanks.
Recorder An instrument that records data such as pressures and temperatures over a period of time.
Recovery (percent recovery)A measurement applied to reverse osmosis and ultrafiltration equipment, which characterizes the ratio of product water to feedwater flow rates. The measurement is descriptive of reverse osmosis or ultrafiltration equipment as a system and not of individual membrane elements.
Rectifier An electrical device that converts alternating current (AC) into direct current (DC).
RadiumNaturally occurring radioactive elements, removed from water by cation exchange softening.
RedoxA shortened term for "oxidation-reduction".
Refractory Brickwork used in boiler furnaces and for boiler baffles.
RegenerantThe chemical solutions used to restore an exhausted bed or ion exchange resin to the fully ionic form necessary for the desired ion exchange to again take place effectively.
RegenerationThe use of chemical solution to displace the contaminant ions deposited on the ion exchange resin during the service run and replace them with the kind of ions necessary to restore the capacity of the exchange medium for reuse.
Regeneration CycleThe several steps including, backwash, applications of regenerant, dilution and fresh or deionized water rinse necessary to accomplish regeneration of an ion exchange bed or oxidizing filter.
Regeneration LevelThe quantity of regenerant, usually expressed in pounds per cubic floor of ion exchanger bed or pounds per regeneration, used in the regeneration cycle of an ion exchange system.
Regeneration TanksLarge Vessels, either gravity or pressurized in which batches of ion exchange resin used in portable exchange tanks are recharged.
Regeneration WaterAll of the water consumed in the regeneration steps, backwash, regeneration, dilution and rinse.
Regenerative Air PreheaterA combustion air preheater that consists of a rotating segmented wheel containing corrugated metal in each segment. As the rotating wheel passes through the hot flue gases, the corrugated metal is heated. As the rotating wheel passes through the combustion air, the combustion air is heated by the hot corrugated metal.
ReinsuranceInsurance purchased by insurance companies for large-loss contingencies.
Rejection (percent rejection)A measure of the ability of a reverse osmosis membrane to remove salts.
Reject StagingA method used to raise the production rates of reverse osmosis systems by using the reject water from the first stage as the feedwater for the second or succeeding states in the RO process.
Reject WaterA term used in distillation, electrodialysis, reverse osmosis and ultrafiltration to describe the portion of the incoming feedwater that has passed across the membranes but has not been converted to product water and is being sent to the drain.
Relative HumidityThe ratio of the actual amount of water vapor in the air to the greatest amount possible at the same temperature.
Relief ValveA valve that opens in the proportion to the excess pressure, rather than popping open fully.
Remote ControlA control device that is installed a considerable distance from the equipment on which it is being used.
Representative SampleA sample that is exactly the same as the item being tested.
ResetThe act of restoring a switch or other control device or system to service-ready condition after it has been tripped by an unsafe or otherwise prohibited condition.
ResidualThe amount of specific material which remains in the water after the water ha been through water treatment steps.
Residual ChlorineChlorine allowed to remain in a treated water after a specified period of contact time and to provide disinfection protection throughout the distribution system.
Residual Fuel OilFuel oil that remains after the lighter, more volatile hydrocarbons have been distilled off.
ResidueThe dry solids remaining after the evaporation of a sample of water or sludge.
ResiliencyThe ability of a material to return to its original shape after being deformed.
ResinAs used in the water processing industry, this term refers to ion exchange resin products which are usually specifically manufactured organic polymer beads used in softening and other ion exchange processes to remove dissolved salts from water.
Resin CleanerOne of the several different chemical compounds used to cleanse ion exchange resin products of dissolved iron, aluminum, and various organics attracted to or bonded to the resin beads.
ResistanceThe measure of the ability of an electric circuit to oppose current flow.
ResistivityResistivity is a measure of the current-resisting characteristics of a substance when an electrical charge is applied. The standard unit of resistance is the Ohm. Because of the variable nature of water, a distance between measuring probes must be maintained if accurate measurements are desired. The almost universal standard distance for this is the centimeter, hence the "Ohm-cm". Resistivity measurements, like conductivity measurements can be used in many ways to improve the management of a water purification system, and are commonly used to assess the quality of water produced by deionizers. Because temperature affects resistivity of water, temperature-compensating devices are frequently used. These adjust the resistance meter to indicate what the water resistance would be at one temperature, usually 25°c.
RetentionIn membrane filtration, retention describes the minimum particle or molecule size retained by the membrane under a set of conditions, namely, pressure, Flux recovery and temperature.
RetortA V-shaped trough, usually about 5' to 12' long, with a back plate enclosing the rear end of the trough opposite the feeding mechanism. Solid fuel is fed by the feeding mechanism into the bottom of the trough and slowly overflows onto grate bars.
Retort ChamberA V-shaped trough, usually about 5' to 12' long, with a back plate enclosing the rear end of the retort opposite the feed ram.
Retort StokerA stoker in which both the fuel and the combustion air are fed from below the combustion zone.
Reverse DeionizationThe use of the anion exchange resin ahead of the cation exchange resin in a deionization system.
Reverse OsmosisA water-purification process in which the water to be treated is pressurized and applied against the surface of a semipermeable membrane.
Ringelmann ChartA comparison chart used to measure opacity.
RinseThe step in the regeneration process in which fresh water is passed through the bed or resin to remove any excess or spent regenerate prior to placing the softening into service
Riser TubesTubes exposed to the highest temperatures in the furnace area and contain rising water.
Rising Stem ValveA valve that has a handwheel and stem that move outward from the body of the valve as the valve is opened.
RotameterA variable-area instrument used for measuring rate of flow.
Rotary Cup BurnerA fuel oil burner that has a spinning cone-shaped cup, usually made of brass or stainless steel. Fuel oil is mixed with air as the oil is sprayed from the rim of the spinning cup.
Rotary PumpA pump with a rotating shaft. A rotary pump may be either a dynamic pump or a displacement pump.
RTDAn acronym for resistance temperature device.
Sacrificial Anode An anode made of suitable metal placed in a water heater tank to protect the tank from corrosion.
Safety Relief ValveA valve specially designed to serve as either a safety valve or relief valve, depending on the application for which it is used.
Safety ValveA valve that opens fully and instantly and causes a definite, measured drop in pressure before closing.
SalimeterThe hydrometer which measures the percent of salt in a brine or other salt solution.
SalineConsisting of, or containing, salt.
Saline SolutionAny solution with the total dissolved solids usually ranging from 15,000 to 30,000 mg/L.
SalinityThe relative concentration of dissolved salts, usually sodium chloride, in given water.
SalinometerAn instrument for determining the salt concentration of brine water by measuring the electrical conductivity of the solution.
SaltA chemical compound formed by neutralization of an acid with a base.
Salt BlockEvaporated salt or fine rock salt which is mechanically compressed into dense block.
Salt BridgingThe creation of salt encrustment and cementing together of salt particles in dry storage brine tanks, which cause tight bonding of the entire salt mass to the walls of the brine take and prevents the salt from dropping into the incoming water for brine makeup.
Salt CakeSodium sulfate which is only 90-99% pure.
Salt EfficiencyThe hardness removal capacity of a water softener unit calculated as grains of hardness removed divided by the weight of salt in pounds that is used to achieve that amount of hardness reduction.
Salt Passage RateA measurement of the passage of salts through a reverse osmosis membrane. Salt passage is related to rejection.
Salt SplittingAn ion exchange process in which neutral salts in water are converted to their corresponding acids or bases.
Salt Splitting CapacityA regular test used on an ion exchange resin to determine the capacity of a used resin versus the standard rated capacity of the resin when fresh.
Salt WaterThe general term for all water over 1,000 PPM total dissolved solids.
Sample CoolerA small, closed heat exchanger that cools condensate or other hot water to a temperature below about 130°F to 140°F before the water emerges from the cooler and into a sample container.
Sample CouponA small, flat strip of steel that is inserted into an elbow or tee fitting in a piping network.
SandSoil particles between 0.05 and 2.0 MM in diameter.
Sand filterThe oldest and most basic filtration process which generally uses two grades of sand for turbidity removal or as the first state of rough filtering.
Sand TrapA mechanical device to separate fine sand or other abrasive material from water in wells with faulty screens.
SanitizeTo reduce the number of bacterial contaminants to a safe level as judged by public health requirements.
SanitizerAn agent that results in the reduction of bacterial numbers to accepted public health limits by sanitizing.
SaturatedMeans that a substance has absorbed as much of another substance as it can absorb.
Saturated SteamA steam that contains no liquid water and is at the temperature of the boiling water that formed the steam.
SaturatorA device which produces a fluoride solution from the fluoridation process.
ScaleDeposits caused by improper boiler water treatment. learn more about scale
ScalingIn reference to reverse osmosis equipment, scaling is the precipitation of sparingly soluble salts such as calcium carbonate onto the surface of the membrane. Scaling is associated with decreased flux and reduced reverse osmosis rejection.
ScannerDevice that monitors the pilot and main flame of the furnace. The scanner is used to prove the pilot and main flame.
ScavengerA polymer matrix or ion exchanger that is used specifically to remove organic species from the feedwater before water is to pass through the deionization process.
Scotch Marine BoilerA firetube boiler that has a flue furnace and horizontal shell.
ScrubberDevice that removes undesirable gaseous elements from flue gas.
Secchi DiscA flat, white disc, lowered into the water by a rope unit it is just barely visible. At this point, the depth of the disc from the water surface is recorded secchi disc transparency.
Secondary AirAir mixed with the fuel to ensure that enough oxygen is available to complete the burning.
Secondary TreatmentThe process which makes up the second step in treating waste water and removes suspended and dissolved solids and biochemical oxygen demand from the waste water which has already undergone primary treatment.
Second Law Of Thermodynamics Heat always flows from a body having a higher temperature toward a body having a lower temperature.
SedimentParticles of solid foreign matter that settle out from a body of liquid.
SedimentationThe process by which solids are separated from water by gravity and deposited on the bottom of a container or basin.
Seize UpSeize up Occurs when an engine overheats and part expands to the point where the engine will not run.
Selective Ion ExchangerAn ion exchange medium which shows selectivity.
Selectivity The tendency of an ion exchanger to prefer certain kinds of ions over others.
Selectivity BandThe respective region and zone within an ion exchanger or adsorption medium bed where individual ions or substances accumulate and are removed from the water in order of their individual respective preferences for the medium.
SEMISemiconductor Equipment and Materials International.
Semiclosed Impeller An impeller that has a shroud on one side of the vanes.
Semiconfined AquiferAn aquifer that is partially confined by a soil layer or low permeability through which recharge and discharge can occur.
Semi-permeableDescriptive of a material such as a reverse osmosis or ultrafiltration membrane, which allows the passage of some molecules and ions and prevents the passage of others.
Sensible Heat The BTU content of a substance that represents the heat absorbed or given up as it changes temperature.
Sensor An electrical or electronic device which measures the quality of the product water leaving the treatment cycle.
SepralatorA spiral wound membrane element or cartridge used in crossflow membrane systems.
SequesterTo keep a substance in solution through the addition of chemical agent that forms chemical complexes with the substance.
Serial FiltrationThe arrangement of two or more filtering steps, one following the other, in order to remove increasingly finer particulates at each stage and provide for filtration of all sizes of suspended solids.
SeriesIn water purification an arrangement of equipment in a successive or end to end configuration.
Service FlowThe rate in US gallons per minute or liters per minute at which a given water processing system can deliver product water.
Service RunThat portion of the operating cycle of a water processing system during which the water is actually being treated.
SessileAttached firmly to a permanent base and not free to move about.
SetpointThe desired point at which an automatic controller maintains a variable condition within a process.
Shakeout The process of operating a new system as needed to expose and correct the major impediments to reliable operation.
Shallow WellA well sunk in easily, penetrated ground to a point which is below the water table.
Shaft SleeveA replaceable sacrificial part covering a pump shaft.
Shear The exertion of equal forces in opposite direction in the same plane.
Shearing ActionThe action of low temperature water flowing at a high rate which splits and separates particles agglomerations, and prevents the formation of floc deposits during the coagulant free/filtration process.
Shear Pin A link used in a mechanical drive that is designed to break under a specific amount of shear stress.
Shielded Metal Arc Welding A welding process that uses an electric arc to heat the metal in the weld area; metal from te electrode is added to the weld pool.
ShieldingThe separation and insulation of metal parts of a pipe joint by a special fitting which will not conduct electric current.
Shock LoadThe arrival at a water treatment system of raw water containing unusual amounts of algae, colloidal matter, color, suspended solids , turbidity and other pollutants.
Short CircuitingA condition that occurs in tanks or basins when some of the water travels faster than the rest of the flowing water.
Signal The language that the control devices use to communicate with each other.
SilicaAs used in water Chemistry, a collective term encompassing all reactive and inert forms of chemically resistant dioxide of silicon or silicates formed from silicon and oxygen combinations with one or more other minerals or metals.
SiltSoil particles between 0.05 to 0.002 Millimeter in approximate diameter.
Silt Density Index (SDI)The silt density index is a measure of the ability of water to foul a membrane element or flug a filter. SDI is measured using an apparatus which typically consists of an inlet pressure regulator and pressure gauge followed by a filter holder containing a 0.45-micron microporous membrane filter. Commercial test kits, complete with instructions on how to calculate the index are available.
Simplex Pump A steam-driven, reciprocating, positive-displacement, double acting pump with one steam cylinder and one liquid cylinder.
Single-Acting PumpA reciprocating pump that moves fluid in only one direction of the stroke.
Single-Loop Control The use of a controller to control a single process variable without any influence from any other controller or process variable.
Single- Stage PumpA pump that has only one impeller.
Single- Stage RecirculationProcess used in a multiple membrane reverse osmosis system in which a portion of the concentrate stream is split off and routed back to the inlet and mixed with the feedwater.
Single- Stage SystemA reverse osmosis system in which the water is passed through the membranes only once by using a single high pressure pump.
SiphonA device used between the source of steam and the Bourdon tube in a steam pressure gauge to prevent the heat of the steam from damaging the Bourdon tube.
Slag The solid deposits that accumulate on furnace walls and boiler tubes.
Slag Screen A loosely spaced bank, or several rows of water tubes placed between the superheater and the combustion area of the furnace.
Slaker A conveyor in which lime is mixed with water to make a soluble paste.
Slinger RingA metallic ring that hands on the rotating shaft of a machine and delivers oil from an oil sump to a bearing.
Slip The difference between calculated and actual displacement of a pump.
SloughingThe action of a medium casting off into the effluent stream any substance intended for removal from the water.
Slow-Opening Valve A valve that requires five or more ful turns of a handwheel to move the valve from fully closed to fully open.
Slow RinseThe portion of the (ion exchange) rinsing stage which usually follows the introduction of the regenerant and during which the rinse water passes through the resin at the same flow rate as the regenerate.
Slow Sand FiltrationA process involving passage of raw water through a bed of sand at low velocity resulting in substantial particulate removal by physical and biological mechanisms.
SludgeAccumulated residue produced from impurities in water.
SlugA temporary abnormally high concentration of an undesirable substance which shows up in the product water.
SluiceA trench through which water flows rapidly to carry away solid materials.
Slurry A watery mixture or suspension of insoluble matter.
Smoke Box The area at the end of a firetube boiler where the flue gases are allowed to reverse direction for the subsequent pass.
Smoke Indicator An indicating or recording device that shows the density of the smoke leaving the chimney.
Soda AshA common water treatment chemical, sodium carbonate, which is used for pH modification.
SodiumA metallic element found abundantly in compounds in nature but never existing alone.
Sodium BicarbonateA mild alkali, commonly called baking soda.
Sodium CarbonateA fairly strong alkaline salt occurring naturally as soda ash.
Sodium ChlorideThe chemical name for common table salt.
Sodium CitrateThe sodium salt of citric acid.
Sodium CycleThe cation exchange water softening process in which sodium ions in the resin are exchanged for hardness ions in the water.
Sodium HexametaphosphateA substance that has a molecular ration of 1.1 parts sodium monoxide to 1 part Phosphorus pentoxide.
Sodium HydrosulfiteA crystalline salt which is a strong reducing agent and the main ingredient in several resin cleaners.
Sodium HydroxideA strong alkaline compound used as a regenerant for anion exchange resin in deionization systems.
Sodium HypochloriteLiquid Bleach, used as a source of chlorine in water treatment.
Sodium MetaphosphateAny of several complex phosphates with excellent sequestering properties.
Sodium SilicateGlassy polymeric silicates used to prevent corrosion by formation of thin passivating film on metal surfaces.
Sodium TripolyphosphateA crystalline salt used chiefly as a water softener, sequestering agent and deflocculation agent, especially in soaps and detergents.
Sodium Zeolite Water Softener An ion-exchange water softener that uses resin beads and a brine solution to soften water.
Softened WaterAny water which has been processed in some manner to reduce the total hardness to 17.1 mg/L or ppm or less expressed as calcium carbonate equivalent.
Soft WaterAny water Which contains less than 1.0 grain per gallon.
Solar Saltcommon salt which is produced by solar evaporation in shallow ponds, under in softener regeneration.
SolderA metallic compound used to seal the joints between pipes.
Solenoid An electric actuator that consists of an iron plunger surrounded by an encased coil of wire.
Solenoid Valve A valve that is snapped open or closed by an electric actuator.
SoluteThe substance which is dissolved in the solvent.
SolutionA mixture in which one or more substances are dissolved into another substance, usually a liquid, in such a way that the solute is equally distributed throughout the solvent.
SolventA liquid substance that dissolves another substance to form a solution.
SorptionA surface phenomenon which may be either absorption or adsorption, or combination of the two.
Soot Carbon deposits caused by incomplete combustion.
Soot Blowers Used to remove soot from around tubes to increase boiler efficiency. Mostly found on watertube boilers.
Sour BrineBrine that contains high concentration of calcium, magnesium, or other substances that would interfere with its use or reuse for effective regeneration of exhausted ion exchange resin.
Spalling Hairline cracks in boiler brickwork (refractory) due to changes in furnace temperature.
Specific Gravity The weight of a given volume of a material divided by the weight of an equal volume of water when both are measured at the same temperature.
Specific Volume The space occupied by a fluid or gas of a particular unit of weight under specified condition of pressure and temperature.
Spectrophotometer An instrument that measures the ability of different frequencies of light to pass through a sample of liquid.
SphericityThe measure of the bead roundness or whole bead count of beads in an ion exchange resin product or other bead form adsorbent or filter medium.
Spiral woundA very common construction configuration for one style of reverse osmosis membrane and cartridge filter element.
Split Stream TreatmentThe art of proportionally blending a stream of treated water with a stream of untreated, from the same source to achieve a lower measurement of a given contaminant in the blended system,thus not removing all of the contaminant but still meeting the water quality desired.
Spontaneous Combustion The process where a material can self-generate heat until the ignition point is reached.
Staged Combustion The introduction of the combustion air at sequential points over the length of the burner housing to control the quantity of oxygen available at any given point.
Staging The placement of more than one impeller on the same shaft in a centrifugal pump.
Standard An accepted reference, practice, or method.
Standard MeshThe typical size of water treatment media, Standard mesh size 16-50 mesh.
Standing Pilot A gas pilot that is always lit.
StartersDevices used to start up large motors gradually to avoid severe mechanical shock to a driven machine and to prevent disturbance to the electrical lines.
Static Discharge Head The vertical distance from the centerline of the pump up to the surface of the liquid in the tank or vessel into which the piping discharges.
Static Suction Head The vertical distance from the centerline of the pump up to the level of the liquid in the supply tank.
Static Suction Lift The vertical distance from the centerline of the pump down to the level of liquid in the supply source below.
Static SystemA system or process in which the reactants are not flowing or moving.
StayboltA short bolt brace that passes through the water leg of a boiler.
Steam The gaseous form of water.
Steam and Water Drum The pressure vessel in a steam boiler that contains both steam and water.
Steam Blanketing A condition that occurs when steam bubbles are generated so quickly from a boiler heating surface that a layer of steam is formed between the water and the heating surface.
Steam BlowingThe process of cleaning impurities from new piping by blowing steam through the pipe.
Steam BoilerA closed vessel in which water is transformed into steam under pressure through the application of heat.
Steambound Condition that occurs when the temperature in the open feedwater heater gets too high and the feedwater pump cannot deliver water to the boiler.
Steam Header A manifold that receives steam from two or more boilers and provides a single location from which steam may be routed through the steam mains and branch lines to various points of use.
Steam MainThe piping that carries steam to a section of a building or plant.
Steam Rate The combination of combustion efficiency and the thermal efficiency at the full range of loads and conditions that the boiler encounters over a typical period of time. The steam rate is expressed as average pounds of steam generated per unit of fuel.
Steam Separator Device sued to increase the quality of steam. Found in the steam and water drum.
Steam Space The space above the water line in the steam and water drum.
Steam System Consists of the equipment, controls and piping that carry the steam generated by the boiler to its point of use.
Steam System Efficiency A measurement of steam usage that takes into account both the equipment supplying the steam and the equipment demanding the steam.
Steam Tracing A small copper or steel tube which is supplied with steam and is usually run alongside a process pipe to keep the fluid within the pipe warm.
Steam Trap A mechanical device used for removing condensate and/or air from steam piping and heat exchange equipment.
Steam Trap Survey The process of identifying, testing and documenting the condition of all steam traps in a facility.
Steam Turbine A rotary steam engine used to drive rotating equipment such as pumps, blowers, compressors, or electric generators.
Steam Working Pressure (SWP) The maximum steam working pressure of the valve.
Stellite An alloy of chromium, cobalt, and tungsten.
SterilizationA physical or chemical process that reduces the number of organisms to a safe predetermined level.
Stirling Boiler A watertube boiler design with three steam and water drums on the top and mud drum beneath, interconnected by a large number of water tubes.
StokerA device that automatically feeds green, unburned coal and other solid fuel to a furnace.
Stoichiometric Combustion The process of burning fuel with precisely the amount of air required so that no unburned fuel or unused oxygen remains.
Stopcock A quick-opening or closing valve usually found on gas lines.
Storage TankA compartment used to accumulate the product water from a water treatment unit.
Straight-Tube Watertube Boiler A boiler design in which the steam-generating tubes are straight rather than bent or curved.
Strainer A pipeline fitting containing a mesh or perforated metal screen used to capture impurities that could damage or interfere with the operation of another component, such as a steam trap, pressure-reducing valve, or turbine throttle valve.
Stratified BedA bed in which 2 exchangers of different classes are different densities have been placed in the same column, such as a weak base anion resin on top of a strong base anion exchanger or in a cation exchange systems a weak acid on top of a strong acid resin.
String Wound ElementA Cartridge style filter element constructed by continuous spiral winding of natural or synthetic yard around a performed product water tube core and then building it up in layers to form a depth type filter element.
Strong Acid Cation ExchangerA cation exchange resin with an exchange site group capable of splitting neutral salts to form their corresponding free bases.
Strong Base Anion ExchangerAn anion exchange resin with an exchange site group capable of splitting neutral salts to form their corresponding free bases.
StyreneA fragrant, liquid, unsaturated hydrocarbon used chiefly in the manufacture of synthetic rubber, resins and plastics.
Submerged Arc Welding (SAW) A welding process in which an electric arc is submerged or hidden beneath a granular material (flux).
Submerged Conveyor A heavy steel pan conveyor or apron conveyor immersed in a water trough.
Submerged-Tube Vertical Boiler A firetube boiler with fire tubes completely covered with water all the way to the upper tube sheet.
SubmergenceThe distance between the water surface and the media surface in a filter.
Submersible PumpA pump designed to fit inside the well casing and to operate below the water level in a drilled well.
Submicron Filter A cartridge type membrane filter used in fine particle separation applications to remove particulates of less than one micron in the size.
Suction Liftthe negative pressure on the suction side of the pump.
Suction Pressure Pressure on the liquid at the suction side of a pump.
Sulfate BacteriaSulfate reducing bacteria.
SulfideAn anion often present in groundwater.
Sulfonic AcidA specific acidic group which forms the exchange site active group in certain cation exchange resins and gives these resins their ion exchange capability.
SulfurA yellowish solid chemical element.
Sulfuric AcidA very strong, corrosive and hazardous acid used as a regenerant for the cation stage of an ion exchange deionization system.
Sulfur WaterWater containing objectionable amounts of hydrogen sulfide, which causes an offensive rotten egg odor.
SuperchlorinationThe addition of excess amounts of chlorine to a water supply to speed chemical reactions or ensure disinfection within a short contact time.
Superficial VelocityThe velocity of a fluid flowing through a tank containing a bed of particles is described in terms of the superficial velocity. The superficial velocity is defined as the velocity that would be achieved by the fluid if it flowed at the same volumetric flow rate through the tank when it was empty of particles.
Superheated Steam Steam that has been heated above the saturation temperature.
Superheater A bank of tubes through which steam passes after leaving the boiler, in which additional heat is added to the steam. This causes the steam temperature to rise significantly above the saturated prior to boiler startup.
Superheater Drain A valve and line installed at the low point of drainable superheaters that allows condensate to be removed from the superheater prior to boiler start up.
Superheater Header Main inlet and outlet line to and from the superheater tubes in the superheater.
Superheater VentA vent to the atmosphere provided at the superheater outlet so that a flow of steam may pass through the superheater and out the roof of the plant while a boiler in battery is being heated before being put on-line.
SupernatantLiquid removed from sludge.
Supersaturated SolutionAn unstable condition or a solution in which the solution contains a substance at a concentration greater than the saturation concentration for the substance.
Support Media BedMaterial of a specific graded particle size used as a subfill to support the primary medium bed.
Surface Blowdown The process of intermittently removing water from a boiler to control the quantity of impurities in the remaining water or to remove a film of impurities on the water.
Surface PumpA mechanism for removing water or waste water from a sump or wet well.
SurfactantA surface active substance that when added to water lowers surface tension and increases the wetting capabilities of the water.
Surge TankA type of pressurized water storage vessel also known as a bladder tank. Used almost exclusively on residential well water systems, they provide a small amount of pressurized water downstream valves or equipment without requiring a pump. When installed on a piston type pump, they reduce violent pressure spikes. Surge tanks typically have large areas of stagnation that offer opportunistic bacteria a favorable environment for multiplication.
Suspended Solids Solid impurities that are suspended in water.
Suspension SlingUsed to support the drum of an HRT boiler.
Sweet BrineBrine that contains sufficient sodium and potassium content and is relatively low in calcium, magnesium or other interfering substances such that it is effective for use of reuse in regenerating exhausted ion exchange resin.
SwellThe rise in the boiler water level that occurs when the steam load on the boiler is increased or when the steam pressure drops.
Synchronize The process of bringing the process variable condition very near the setpoint of an automatic control before switching between manual mode and automatic mode.
SynergismThe combined action of several chemicals which produces a greater effect than would be obtained by simply adding together the effects produced by each chemical separately.
Tagout The used of a danger tag at the source of the hazardous energy to indicate to other personnel that the device is not to be operated until personnel working on the equipment have removed their lockout devices and the equipment is safe to operate.
Tandem Valve A blowdown valve configuration with two valves in series machined into a common valve body.
Taste ThresholdA the minimum concentration of a chemical or biological substance which can be tasted.
TDSTotal Dissolved Solids.
TDS CreepThe appearance of salt in the RO product water which sometimes occurs as a result of the reduction of differential pressure across the membrane as can occur with RO unit has been shut down for a long period of time.
Technical Society An organization made up of personnel having expertise in a particular subject and a common professional interest.
TeflonTrade name for high temperature industrial plastic.
Temperature SensorA device that opens and closes a switch in response to change in temperature.
Temporary Hardness A type of hardness that can be reduced by heating the water.
Tensile Strength The amount of force required to pull an object apart.
Tension The exertion of equal forces pulling in opposite directions that can stretch an object.
Tertiary Air Combustion air added to a burner in addition to and downstream of the secondary air.
Tertiary TreatmentThe third state of treatment that brings water to a high degree of refinement or conditioning following the reduction of substances in the primary and secondary stages of treatment.
Therm A unit of measure indicating 100,000 BTU
Thermal Efficiency The ratio of the heat absorbed by the boiler to the heat available in the fuel per unit of time.
Thermal Fluid Boiler A firetube or watertube boiler that uses a chemical solution instead of water.
Thermal ConductivityThe ability of a substance to conduct heat.
Thermal N0x N0x that is formed as a result of the combustion air when the molecules of nitrogen and oxygen in the air separate under high-temperature conditions and then bond together again as the temperature is reduced.
Thermal Shock The stress imposed on boiler metal by a sudden and drastic change in temperature.
Thermocouple A device used to measure temperature consisting of two dissimilar metals joined together.
Thermohydraulic Feedwater Regulator A modulating control that controls feedwater flow in direct response to changes in the boiler water level. This regulator utilizes changes in temperature to create changes in hydraulic pressure and this hydraulic pressure is used to operate the feedwater regulating valve.
ThermometerInstrument used to measure temperature. Calibrated in degrees Celsius or Degrees Fahrenheit.
Thermostatic Expansion Tube Feedwater RegulatorA modulating control that controls feedwater flow in direct response to changes in the boiler water level. This regulator utilizes the expansion and contraction of a long, slightly tilted expansion tube to create a proportional movement of the feedwater regulating valve.
Thermostatic Steam Trap A steam trap that contains a temperature-operated device, such as a corrugated bellows, that controls a small discharge valve.
Thermowell A receptacle into which a temperature sensing instrument is inserted.
Thin film Composite Membrane (TFC)A class of reverse osmosis membranes made with polyamide based polymer and fabricated with different materials in the separation and support layers.
ThiobacillusA genus of bacteria that obtain their energy from oxidation of sulfides, thiosulfates or sulfur, forming sulfur, persulfates, sulfuric acid and sulfates.
Three-Element Feedwater Regulating System A water level control system that measures the steam flow from the boiler and the feedwater flow into the boiler in addition to the water level.
Threshold Lowest dose of a chemical at which a specified measurable effect is observed and below which is not observed.
Threshold OdorThe minimum odor of a water sample that can just be detected after successive dilutions with odorless water.
Threshold Odor NumberThe greatest dilution of a sample with odor free water that still yields a just detectable odor.
Throughput VolumeThe amount in gallons or liters of water passed through an ion exchange resin bed or water treatment system before exhaustion of the exchanger or system is reached.
Throttling Controlling the amount of flow that passes through a valve by partially closing it.
Thrust BlockA mass of concrete of similar material appropriately placed around a pipe to prevent movement when the pipe is carrying water.
Time LagThe time required for processes and control systems to respond to a signal or to reach a desired level.
Titration Test A test that determines the concentration of a specific substance dissolved in water.
Titratable AlkalinityWhen certain anions, such as carbonate (CO3-), are dissolved in water, they bind hydrogen ions (H+) and thus shift the water equilibrium to produce free hydroxyl ions (OH-). This excess concentration of OH- is termed alakalinity. Titratable alkalinity can be measured by determining the amount of H+ which must be added to water to restore the pH to 7.0 the condition of neutrality.
Total Dissolved Solids (TDS)The sum of all organic, inorganic and ionic contents in a solution (excluding all dissolved gasses). Since a TDS meter cannot measure non-ionic content of water, most TDS readings are an approximation. TDS measurements are widely used in the water and waste water industries monitor final water quality. The TDS meter derives its value from resistivity and conductivity measurements of the product water.
Total Dissolved Solids (TDS) A measurement of the concentration of impurities in boiler water.
Total Dynamic Head The total amount of head produced by the pump and available to perform useful work, after losses have been subtracted.
Total ForceThe pressure (in psi) being exerted on a surface multiplied by the area of the surface.
Total Heat The sum of sensible heat and latent heat.
Total Organic CarbonOrganic compounds dissolved in water are characterized by their carbon content. Total organic carbon is the mass of carbon present in a water sample excluding the carbon present as CO2 and/or carbonates.
Totalizing Flowmeter A flow measuring device that not only measures on an instantaneous basis, but also measures total flow over time.
ToxapheneA chemical that causes Adverse health effects in domestic water supplies.
Trade Association An organization that represents the producers of specific products.
Transducer A device that converts one type of control signal into another type of control signal.
Transient Water SystemA non community water system that does not serve 25 of the same non resident persons per day for more then 6 months of the year.
Transmission LinesPipelines that transport raw water from its source to a water treatment plant.
TransmitterAn instrument used to send information about the condition of a process to a control device. A device that conditions a low-energy signal from the primary element and produces a suitable signal for transmission to other components and devices.
Treated Waste WaterWaste water that has been subjected to one or more physical, chemical and biological processes to reduce its pollution of health hazard.
Tricock A valve used as a secondary water level indicator.
Trigger PointA stage in a demand initiated regeneration water softener or valve control cycle when the unit is ready for regeneration.
Tubercle A bump on a steel boiler surface made up of corrosion products.
TurbidHaving a cloudy or muddy appearance.
Tubular Air Preheater Consist of tubes enclosed in a shell where flue gases heat up incoming combustion air.
TurbidityTurbidity is a measure of the presence of colloidal matter in the water that remains suspended. Suspended matter in a water sample, such as clay, silt or finely divided organic and/or inorganic material will scatter the light from an incident light beam. The extent of scattering is expressed in Jackson or Nephelometric turbidity units (JTU and NTU, respectively).
Turbine Pump A rotary positive-displacement pump that uses a flat impeller with small flat perpendicular fins machined into the impeller rim.
Turbine Stages That part of the turbine where steam gives up its energy to the turbine blades. As the steam pressure drops, the stages (blades) become larger.
Turbine Tube Cleaner A motorized mechanical cutter or knocker that removes scale from boiler tubes.
Turbulator Device that swirls the hot gases of combustion as the gases pass through the center of the tube so that the gases come into more efficient contact with tube walls where heat transfer occurs.
Turbulence 1.) Agitation at the water level inside a boiler. 2.) Agitation of a flame for the purpose of thoroughly mixing the combustion air and fuel.
Turbulence PromoterDevices which are inserted into the feedwater channel or the product water channel to increase the turbulence and improve the mixing characteristics of the fluid flow.
Turndown Ratio The ratio of the maximum firing rate of the burner to the minimum firing rate.
Tuyere (Tweer) A special air-admitting grate designed to start combustion of the entering fuel.
Two-Element Feedwater Regulating System A water level control system that measures the steam flow from the boiler in addition to the water level.
Type 1 ResinA strong base polystyrene/Divinylbenzene anion exchange resin in which the exchange site is a trimethylamine.
Type 2 ResinA strong base polystyrene/Divinylbenzene anion exchange resin in which the exchange site is a dimethylethanol amine.
Ultimate Analysis The percentages of nitrogen, oxygen, carbon, ash, sulfur and hydrogen in the coal. (NOCASH)
Ultra FiltersA membrane based filtration system in which the pore size ranges from .001 to .1 microns
UltrafiltrationA method of crossflow filtration which uses a membrane to separate small colloids and large molecules from water and other liquids.
Ultrapure WaterHighly treated water that is deionized and mineral free with high resistivity and no organics.
Ultraviolet AbsorberSubstances which absorb ultraviolet radiation.
Ultraviolet ChamberThe area where the water is irradiated with UV rays.
Ultraviolet DemandThe amount of ultraviolet rays required to inactivate certain microorganisms.
Ultraviolet DosageThe amount of disinfectant ultraviolet rays delivered to the organisms in the water being disinfected.
Ultraviolet Light (UV)Radiation having a wavelength shorter than 3900 angstroms, the wavelength of visible light and longer then 100 angstroms.
Unaccounted for WaterA term used by public and municipal water systems to describe the difference between the amount of finished water produced and the amount registered on meters sold.
Unconfined AquiferAn aquifer containing water that is not under pressure.
Unfired Vessel A pressure vessel without combustion equipment, such as compressed air tanks, feedwater heating tanks, steam piping, steam jacketed heat exchangers and similar vessels.
Upflow BriningIs a means of forcing the brine solution upward through the cation exchanger for regenerating the resin.
Upflow SofteningA pattern of water flow used in softeners in which the service water flows upward through ion exchange beds.
Utility Watertube Boiler An extremely large watertube boiler that generates steam at a very high pressure and temperature.
U-Tube ManometerA manometer configured in the shape of a long U and calibrated in inches. When filled with mercury, it is used to measure vacuum in inches of mercury. When filled with water, it is used to measure draft conditions in inches of water.
Vacuum A pressure lower than atmospheric pressure.
Vacuum Breaker A check valve that prevents the formation of a vacuum in a tank, pressure vessel, or piping system.
Vacuum DistillationDistillation that occurs at a pressure somewhat below atmospheric pressure.
Vacuum filtrationThe filtration process in which a partial vacuum is applied to increase the rate of filtration by causing the water to be sucked through the filter medium.
Vacuum Freezing A form of desalination using a vacuum to help cool and fast freeze high TDS source water which separates the solids by concentrating them in the portion of the water that doesn't freeze or that freezes last in a similar manner to what occurs in the cloudy centers of ice cubes.
Vacuum GaugePressure gauge used to measure pressure below atmospheric pressure that is calibrated in inches of mercury.
Vacuum PanAn airtight container used to produce granulated water softener salt using a process involving the evaporation of brine turned to steam in a partial vacuum.
Vacuum Pump A pump that withdraws gases or vapors from a closed container and creates a vacuum in the container.
Vane Pump A rotary positive displacement pump that uses a rotating drum located eccentrically inside a cylindrical pump casing.
ValidationDetermination upon testing that a representative sample of a water treatment equipment model has met the requirements of the specified standard.
Vapor Pressure The equilibrium pressure where the number of molecules evaporating from a liquid surface equals the number of molecules condensing back to the liquid.
Vaporstat Control with a large diaphragm that makes it highly sensitive to low pressure.
Variable-Area Flow Meter Measures the flow of a substance by how much resistance is created by a float or piston that changes the area (size) of the flow path.
Variable Frequency Drive (VFD) An electronic system for controlling the speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor.
Vent Condenser An in-line heat exchanger installed in the vent from a deaerator to the atmosphere.
Venturi A nozzle with a slight hourglass-shaped taper.
VersenateA chemical substance used in water analysis for water hardness or with an indicator to colorimetrically measure hardness quality.
Vertical Firetube Boiler A firetube boiler in which the tubes are oriented vertically.
Viable Treatment ProcessA water of waste water treatment process capable of accomplishing the desired water quality.
Vibrating Grate Stoker Inclined grates that vibrate, causing the fuel bed to move slowly toward the lower end.
VirusThe smaller infectious microorganism, made of RNA or DNA in a protein shell and which grow only in other living cells.
Viscosity A measurement of a liquid's resistance to flow.
Viscous Liquid A liquid that is thick and resists flow.
Volatile Matter Gas given off when coal burns.
Volute A spiral-shaped form.
Warping The bending or distortion of metallic components such as boiler tubes, structural framework, etc. usually caused by overheating.
Waste Heat Recovery Boiler A firetube or watertube boiler in which heat that would otherwise be discarded is used to make steam.
Waste WaterWater that has been used.
Waste Water Treatment PlantA facility that receives waste water from domestic and industrial sources and by a combination of physical, chemical and biological processes reduces the waste water to less harmful byproducts.
Waterborne DiseaseA disease, caused by a bacterium or organism able to live in water.
Water Column A metal vessel installed on the outside of the boiler shell or drum at the normal operating water level (NOWL) for the purpose of determining the location of the water level.
Water Column Blowdown Valve Valve on the bottom of the water column used to remove sludge and sediment that might collect at the bottom of the water column.
Water ConditioningThe treatment or processing of water, by any means, to modify, enhance, or improve its quality or to meet specific water quality need, desire or set of standards.
Water GlassThe common name of a sodium silicate substance used for corrosion control in potable waters.
Water HammerThe hydraulic shock in piping caused by the presence of liquids in the steam flow.
Waterlogged TankA tank in which too much water has accumulated and has replaced some of the air in the tank's air cushion causing a disruption in the normal pressure pattern needed for pumping and uniform water flow.
Water, Oil, Gas (WOG) The maximum pressure under which the valve may be used with these fluids.
Water Softener SaltSalt suitable for regenerating residential and commercial cation exchange water softeners.
Water Softening The removal of scale-forming salts from water.
Watertube Steam Boiler Boiler that has water in the tubes with heat and gases of combustion around the tubes.
Waterwall Many tubes placed side by side to create a large, flat surface against the furnace walls in a watertube boiler.
Waterwall Blowdown Valve Approved valve used to remove sludge and sediment from waterwalls and waterwall header.
Weak Acid Cation ExchangersThose cation exchange products with the functional groups which, in the hydrogen form, are not capable of splitting neutral salts to form their corresponding free acids.
Weak Base Anion ExchangersThose anion exchange products with functional groups which are not capable of splitting neutral salts to form corresponding free bases.
Weight-type Alarm Whistle Alarm whistle that signals high or low water by the gain or loss of buoyancy of weights in water within the water column.
WellA bored, drilled or driven shaft, or a dug hole, whose depth is greater than the largest surface dimension and whose purpose is to reach underground water supplies or oil, or to store and busy fluids below ground
Wetback Scotch Marine Boiler A firetube boiler with a water cooled reversing chamber used to direct the combustion gases from the flue furnace to the first pass of tubes.
Wet Salt Saturator TankA type of brine tank, so named because the saturated brine is always above the undissolved salt level, used on large commercial water softeners or older manual residential softeners.
Windbox The plenum to which the forced draft fan (primary air fan) supplies air in order to maintain enough pressure to provide proper air flow through the furnace.
Window Weld A weld made through an opening, or window, in the tube.
Wire Drawing The erosion that occurs as steam or another high-velocity fluid flows through a small opening like a throttled valve.
Working Pressure A shortened term for maximum allowable working pressure, but it may also be used to mean the pressure at which the boiler is normally operated.
XLPECrossed Linked Polyethylene.
YieldThe amount of product water produced by a water treatment process.
Zeolite A synthetic sodium alumina silicate cation-exchange material based on naturally occurring class called zeolites.
Zeolite SofteningA term formerly used for the removal of calcium and magnesium hardness from water by base exchange using natural or synthetic zeolites.
Zero Discharge WaterA discharge limit applied to manufacturing and commercial establishments in which only normal human sanitary waste waters may be discharged to the municipal sewage system.
Zero Soft WaterWater produced by the cation exchange process and measuring less than 1.0 grain per US gallon as calcium carbonate.
Zeta PotentialThe electrical potential which exists across the interface of all solids and liquids.
Zone of SaturationThe layer in the ground in which all available interstitial voids are filled with water.