Adjusted to pH 6.9 with Potassium Hydroxide

CHARGE Amount of refrigerant in a system; to put in the refrigerant charge.

CHARGE DEMAND The anionic or cationic charge needed to attract the conditioning polymer to the sludge.

CHARGE DENSITY The total amount of charge on a given molecule. Charge density is determined by the percentage of charged monomer in a polymer molecule.

CHARGE DISPERSION An overfeeding of polymer that causes ionic charge to overbalance and restabilize the suspension.

CHARGE DISTRIBUTION The arrangement of charged and uncharged monomer units in a specific molecule.

CHARGE NEUTRALIZATION The removal of a portion of the electrical charge on a particle surface by adding a substance with an opposite charge.

CHARGE RADIUS The area that is influenced by an electrical charge.

CHARGE REINFORCEMENT The process of adding a like-charged polymer (usually anionic) to cooling water in order for colloids to adsorb the charge - increasing their repulsive forces.

CHARLES’ LAW The volume of a given mass of gas at a constant pressure varies according to its temperature.

CHECK A condition which results in the development of a series of surface cracks which produces a checkered pattern. The resultant cracks may be superficial or several millimeters in depth and they are usually oriented into a relatively uniform pattern. Checking is most pronounced when the wood is dry. Checking is a characteristic of biological attack although some type of chemical attack can result in surface cracks.

CHECK VALVE A device which permits fluid flow only in one direction.

CHELANT Compounds (EDTA and NTA) that form soluble complexes with hardness. Used to control selective heavy metal deposits.

CHELANT CORROSION A type of corrosion of steel that results from high concentrations of free chelant at high temperature.

CHELATING AGENTS Organic compounds having the ability to withdraw ions from their water solutions into soluble complexes.

CHELATION The act of withdrawing ions into soluble complexes.

CHEMICAL BALANCES Refers to the concentration of soluble compounds in a solution, and generally to those constituents that are important in the cooling system. Chemical compounds that include the NO₃ (nitrate) and NO₂ (nitrite) ions. They are composed of nitrogen and oxygen, are nutrients for growth of algae and other plant life, and contribute to eutrophication.

CHEMICAL EQUATION Symbolic representation of a chemical reaction.

CHEMICAL FAMILY A group of single elements or compounds with a common general name. Example: acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK) are of the "ketone" family; acrolein, furfural, and acetaldehyde are of the "aldehyde" family.

CHEMICAL FEEDING The controlled addition of chemicals into a water system to obtain a specific effect.

CHEMICAL NAME The designation of a chemical in accordance with the Chemical Abstracts Service (CAS) rules of nomenclature or the International Union of Pure and Applied Chemistry (IUPAC) nomenclature system. Any name that will clearly identify the chemical for the purpose of conducting a hazard evaluation.

CHEMICAL OXYGEN DEMAND (COD) The amount of oxygen, expressed in parts per million, consumed under specified conditions in the oxidation of the organic and oxidizable inorganic matter contained in water.

CHEMICAL PRECIPITATION A waste treatment process whereby substances dissolved in the wastewater stream are rendered insoluble and form a solid phase that settles out or can be removed by flotation techniques.

CHEMICAL PRECIPITATION SOFTENING The process of reducing raw water hardness, alkalinity, or silica by adding chemicals that react with the hardness, alkalinity or silica to form insoluble compounds that precipitate and are removed mechanically using solid-liquid separation techniques.

CHEMICAL REFRIGERATION A system of cooling using a disposable refrigerant.

CHEMICAL STABILITY Resistance to chemical change which ion exchange resins must possess despite contact with aggressive solutions.

CHEMICAL TOXICITY The ability of a substance to cause injury as a result of long-term (usually months or years) exposure. Many symptoms of mild chronic toxicity are slow to develop; consequently, the connection between exposure and illness may not be readily apparent.

CHEMTREC Chemical Transportation Emergency Center; a national center established by the Chemical Manufacturers Association (CMA) in Washington, D.C., in 1970, to relay pertinent emergency information concerning specific chemicals on request. CHEMTREC has a 24 hour toll free Telephone Number, (800) 424-9300, intended primarily for use by those who respond to chemical transportation emergencies.

CHILLED WATER LOOP A closed circulating water system which extracts heat from the air or process fluids and, in turn, is cooled by the refrigerant in a chiller.

CHILLER Refrigeration system consisting of five components, the evaporator, the compressor, the condenser, the expansion valve and a closed circulating cooling media.

CHIMNEY EFFECT Tendency of air or gas to rise when heated.

CHIP Integrated circuit created on a silicon slice, containing thousands of electronic circuits.

CHLORIDE Soluble ionic form of element chlorine. Useful as a measure of blowdown or bleed-off control.

CHLORIDE-ANION DEALKALIZATION The is an anion exchange resin system that is regenerated with salt or salt and caustic. It exchanges chloride ions for bicarbonate and sulfate ions in the water being treated.

CHLORINATION The treatment of water by gaseous chlorine or by chlorine releasing agent. Chlorination is most commonly used for making water safe for drinking purposes. In cooling water systems, chlorine is used to control biological fouling.

CHLORINATOR A device used to meter chlorine into a cooling water at a preselected rate.

CHLORINE DEMAND The difference between the amount of chlorine applied to treat a water supply and the amount of free + combined, or total chlorine remaining at the end of a specified contact period.

CHLORINE REQUIREMENT The amount of chlorine, expressed in parts per million, required to achieve under specified conditions the objectives of chlorination.

CHLORINE RESIDUAL The amount of available chlorine present in water at any specified period, subsequent to the addition of chlorine.

CHORDAL THERMOCOUPLE A diagnostic device used during boiler operation to monitor tube metal temperature.

CHROMATE Refers particularly to a chemical type inhibitor containing hexavalent chromium in the compound. Generally considered to be sodium chromate. However, when referring to a chromate treatment, it can include any compound containing the chromate or dichromate radical.

CHROMEpHREE A special zinc/phosphate application that, in one formulation, utilizes the zinc orthophosphate pair along with HEDP for corrosion and scale inhibition, and, in a second formulation, provides copper corrosion control.

CHRONIC EFFECTS Those effects to health which occur following long-term exposure, and which are generally of long duration.

CHRONIC EXPOSURE Applies to symptoms which occur over a period of months or years due to exposure to low level sublethal concentrations.

CHRONIC TOXICITY Adverse (chronic) effects resulting from repeated doses of a substance or repeated exposures over a relatively prolonged period of time. Ordinarily used to denote effects in experimental animals.

-CIDE A term used in this book for those chemicals or preparation that affect any bacterial growth in a system. Instead of using specific terms, such a microbiocide, this term covers all chemicals that affect microbials.

CIRCUIT A tubing, piping or electrical wire installation which permits flow from the energy source back to energy source.

CIRCUIT, PARALLEL Arrangement of electrical devices in which all positive terminals are joined to one conductor and all negative terminals to other conductor.

CIRCUIT, SERIES Electrical wiring: electrical path (circuit) in which electricity to operate second lamp or device must pass through first, and so on; current flow travels through all devices connected together.

CIRCULATING WATER FLOW The amount of hot water flowing into the tower. Units: quantity, lb. per hr. (One U.S. gallon = 8.33 lbs.); volume, GPM; velocity, FPS.

CLARIFICATION The act of removing suspended matter by physical means employing flocculating agents, settling, and filtration.

CLARIFIER A settling basin for separating settleable solids from wastewater.

CLASS I EXPLOSION HAZARD NEMA rating of locations where flammable gases of vapors may be present in the air in quantities sufficient to produce an explosion or ignition (i.e., chemical plants and oil refineries.)

CLASS II EXPLOSION HAZARD NEMA rating of locations where combustible dusts may be present in sufficient quantity to cause hazard. (i.e., flour mills and coal pulverizing facilities.)

CLASS III EXPLOSION HAZARD NEMA rating of locations where the hazardous material consists of easily ignitable fibers of filings that are not normally in suspension in the air in quantities to produce ignitable mixtures (i.e., fiber manufacturing facilities and saw mills.)

CLEARWELL Final collection basin after filtration.

CLOSED CHILL WATER SYSTEMS Closed recirculating cooling water systems usually operated in conjunction with some form of refrigeration or secondary cooling.

CLOSED CIRCULATING WATER SYSTEM Any water system not subjected to evaporation or other losses and having normal make-up demand.

CLOSED COOLING SYSTEM A cooling system that recirculates the same water over and over using secondary heat exchangers to reject waste heat from the system.

CNS Central Nervous System.

CO Carbon monoxide, a colorless, odorless, flammable, and very toxic gas produced by incomplete combustion; also a by-product of many chemical processes.

CO₂ Carbon dioxide, a colorless gas, produced by the combustion and decomposition of organic substances and as a by-product of many chemicals processes. CO₂ will not burn, and is relatively nontoxic although high concentrations, can create hazardous oxygen deficient environments.

COAGULANT A material, which, when added to liquid wastes or water, creates a reaction which forms insoluble floc particles that adsorb and precipitate colloidal and suspended and suspended solids. The floc particles can be removed by sedimentation. Among the most common chemical coagulants used in sewage treatment are ferric chloride, alum and lime.

COAGULANT AID A polymer which is added to a destabilized solution after a primary coagulant.

COAGULATION The clumping together of solids to make them settle out of the sewage faster. Coagulation of solids is brought about with the use of certain chemicals such as lime, alum, or polyelectrolytes.

COALESCENCE The gathering together of coagulatd colloidal liquid particles into a single continuous phase.

COC Cleveland Open Cup; a flash point test method.

COD (Chemical Oxygen Demand) A measure of the amount of oxygen required to oxidize organic and oxidizable inorganic compounds in water.

COEFFICIENT The number of molecules involved in a reaction.

COEFFICIENT OF CONDUCTIVITY The measure of the relative rate at which different materials conduct heat. Copper is a good conductor of heat and therefore, has a high coefficient of conductivity.

COEFFICIENT OF PERFORMANCE The coefficient of performance is a measure of the efficiency of a refrigeration system. The coefficient of performance, COP, is equal to the ratio of the refrigeration effect to the heat of compression per pound of refrigerant.

COEFFICIENT OF VARIATION A measure used in describing the amount of variation in a population. An estimate of this value is S/X where "S" equals the standard deviation and X equals the sample mean.

COIL SHED Portion of the tower structure housing atmospheric (tubular) heat exchangers.

COLD Cold is the absence of heat; a temperature considerably below normal.

COLD LIME SOFTENING Chemical softening and dealkalization of water, without the external application of heat, using lime to induce precipitation of insoluble calcium and magnesium salts. Softening and dealkalization efficiency is often enhanced by the use of flocculants.

COLD PROCESS SOFTENING Chemical precipitation softening accomplished without heating the water.

COLD WATER TEMPERATURE (CWT) Temperature of the water entering the cold water basin before addition of make-up or removal of blowdown.

COLD WORKING Any metalworking operation carried out below the recrystalllization temperature. It consists of plastic deformation at such temperatures and rates that substantial increases in the strength and hardness of metal occur. Visible structural changes include distortion of grains and a reduction in grain size.

COLIFORM Relating to, resembling, or being the colon bacillus.

COLIFORM BACTERIA Those found in the intestinal tract of warm blooded animals and used as indicators of pollution if found in water.

COLLOIDS Matter of very fine particle size, usually in the range of 10^-5 to 10^-7 cm in diameter.

COLLOIDAL SOLIDS Finely divided solids that will not settle in a reasonable length of time. Colloidal solids are in between true solutions and suspensions.

COLOR BODY An organism, dissolved metal, chemical pigment or other substance that tints water.

COLOR COMPARATOR Test equipment for determining concentration of chemical constituents in solution. Test procedure depends on use of reagents that develop characteristic colors with degree of color directly related to concentration of constituent being measured. Comparison is made against standard solutions or artificially colored solutions that represent known concentrations.

COLOR-THROW Discoloration of the liquid passing through an ion exchange material; the flushing from the resin interstices of traces of colored organic reaction intermediates.

COLORIMETRIC The addition of reagents to a known amount of sample to generate color. The developed color is compared visually to colored standards.

COLUMN Framework member; a main vertical supporting member in the tower framework.

COLUMN OPERATION Conventional utilization of ion exchange resins in columns through which pass, either upflow or downflow, the solution to be treated.

COMBINED AVAILABLE CHLORINE RESIDUAL Residual consisting of chlorine combined with ammonia nitrogen or nitrogenous compounds.

COMBINED RESIDUAL CHLORINE Chlorine in combination with ammonia or organic nitrogen compounds.

COMBUSTIBLE A term used by NFPA, DOT, OSHA and others to classify certain liquids that will burn, on the basis of flash points. NFPA, DOT and OSHA generally define "combustible liquids" as having a flash point above 100° F (37.8° C) and below 200° F (93.3° C). Also see "flammable." Nonliquid substances such as wood and paper are classified as "ordinary combustibles" by NFPA.

COMBUSTIBLE LIQUID A liquid having a flashpoint at or above 100° F (37.8° C) but below 200° F (93.3° C).

COMBUSTION The rapid chemical combination of oxygen with the combustible elements of a fuel.

COMBUSTION CATALYST Water- or oil-based chemical that can be added to fuel oil to control the formation of soot during the ocmbustion process.

COMFORT CHART Chart used in air conditioning to show the dry bulb temperature and humidity for human comfort conditions.

COMMINUTOR A device for the catching and shredding of heavy solid matter in the primary stage of waste treatment.

COMPLEX SALTS Compounds formed by the union of two or more simple salts. They can also mean compounds in which the constituent ions may be combined in nonstoichiometric ratios.

COMPOUND GAUGE Instrument for measuring pressures both above and below atmospheric pressure.

COMPOUND REFRIGERATING SYSTEMS System which has several compressors or compressor cylinders in series. The system is used to pump low pressure vapors to condensing pressures.

COMPRESSED GAS A gas or mixture of gases in a container having an absolute pressure exceeding (a) 40 pounds per square inch at 70° F(21.1° C), or (b) 104 pounds per square inch at 130° F(54.4° C) regardless of the pressure at 70° F.

COMPRESSION SETTLING A phase in which particles beneath a high-concentration particle blanket support the blanket’s weight. At this point, the weight of the particles tend to compress them into a thicker, tighter mass.

COMPRESSOR The compressor raises the pressure of the refrigerant so that the refrigerant can be condensed using cooling water.

COMPRESSOR EFFICIENCY The compressor efficiency is the percentage of energy added to the refrigerant by the compressor to the electrical energy used by the compressor motor.

COMPRESSOR HEAD PRESSURE The pressure of the refrigerant at the discharge of the compressor. The head pressure is also sometimes called the condenser pressure.

COMPRESSOR, CENTRIFUGAL A non positive displacement compressor which depends for pressure rise, at least in part, on centrifugal effect.

COMPRESSOR, COMPOUND A compressor in which compression is accomplished by stages, as in two or more cylinders.

COMPRESSOR, MECHANICAL REFRIGERANT A specific machine with or without accessories, for compressing a given refrigerant vapor.

COMPRESSOR, OPEN-TYPE A compressor with a shaft or other moving part extending through a casing to be driven by an outside source of power, thus requiring a stuffing box, shaft seals or equivalent rubbing contact between a fixed and moving part.

COMPRESSOR, RECIPROCATING A positive displacement compressor with a piston or pistons moving in a straight line but alternately in opposite directions.

COMPRESSOR, ROTARY One in which compression is attained in a cylinder by rotation of a positive displacement member.

COMPRESSOR, SEALED REFRIGERANT A mechanical compressor combination consisting of a compressor and a motor, both of which are enclosed in the same housing, with no external shaft or shaft seals, the motor operating in the refrigerant atmosphere.

CONCENTRATION The total mass (usually in micrograms) of the suspended particles contained in a unit volume (usually one cubic meter) at a given temperature and pressure; sometimes, the concentration may be expressed in terms of total number of particles in a unit volume (e.g., parts per million); concentration may also be called the "loading" or the "level" of a substance; concentration may also pertain to the strength of a solution.

CONCENTRATION CELL The connection to two solutions of the same composition but different concentrations by a metal conductor to produce current flow through the circuit.

CONCENTRATION RATIO In an evaporating water system, the ratio of the concentration of a specific substance in the makeup to its concentration in the evaporated water, usually measured in the blowdown.

CONDENSATE The liquid formed by condensation of a vapor. In steam heating, water condensed from steam; in air conditioning, water extracted from air, as by condensation on the cooling coil of a refrigeration machine.

CONDENSATE POLISHER The use of a cation or mixed bed resin to remove impurities from condensate.

CONDENSATE RECEIVER A device that collects process condensate and periodically recirculates the condensate back to the power house.

CONDENSATION Process of changing vapor into a liquid.

CONDENSE Action of changing a gas or vapor to a liquid.

CONDENSER The condenser is a heat exchanger where heat is removed from the refrigerant as it changes from gas to liquid phase.

CONDENSER COOLING WATER VELOCITY The condenser cooling water velocity is the cooling water velocity through the tubes of the condenser in feet per second.

CONDENSER HEAT TRANSFER RATE The condenser heat transfer rate is the rate at which energy is transferred from the refrigerant to the cooling water in the condenser, 1,000 BTU/hr.

CONDENSER, AIR-COOLED REFRIGERANT A condenser cooled by natural or forced circulation of atmospheric air through it.

CONDENSING POINT The temperature at which a gas or vapor changes to a liquid upon removal of heat.

CONDENSING UNIT A specific refrigerating machine combination for a given refrigerant, consisting of one or more power-driven compressors, condensers, liquid receivers (when required), and the regularly-furnished accessories.

CONDENSING UNIT, SEALED A mechanical condensing unit, in which the compressor and compressor motor are enclosed in the same housing, with no external shaft or shaft seal, the compressor motor operating in the refrigerant atmosphere.

CONDUCTANCE Most often used synonymously with conductivity.

CONDUCTION The transfer of heat through a body by molecular motion.

CONDUCTIVITY Ability of a metal or a substance to conduct or transmit heat and/or electricity.

CONDUCTIVITY This represents the current carrying capacity of a water. It is easily determined by applying a fixed voltage between two nonpolarizing electrodes of fixed area and set at a fixed distance apart.

CONDUCTIVITY BRIDGE An instrument comprising a modified Wheatstone Bridge circuit used for determining conductivity or conductance of a solution.

CONDUCTIVITY METER In cooling system application, a device used to control cycles of concentration by measuring the specific conductance of water in (mæ S/cm).

CONDUCTOR Substance or body capable of transmitting electricity, heat, etc.

CONNATE WATER Water produced with oil.

CONSISTENCY In the pulp/paper industry, a term for the density in percent by weight dry matter, of a slurry of pulp.

CONTACT TIME That time that brine, at the proper strength, is moving through the bed of resin. As with most chemical reactions, there must be a minimum length of reaction time for the sodium in the salt (sodium chloride) to completely dislodge and exchange for the accumulated hardness in the resin.

CONTAINER Any bag, barrel, bottle, box, can, cylinder, drum, reaction vessel, storage tank or the like that contains a hazardous chemical. For the purposes of the Federal Standard, pipes or piping systems are not considered to be containers.

CONTAMINANT A substance (dirt, moisture, or other substance) foreign to refrigerant or refrigerant oil in system.

CONTAMINATION A general term signifying the introduction into water of microorganisms, chemical, organic, or inorganic wastes, or sewage, which renders the water unfit for its intended use.

CONTINUOUS BLOWDOWN The intentional, controlled and continuous flow of boiler system water taken from the top or upper section of a boiler to drain.

CONTINUOUS FEED The act of continuously adding chemicals to a water in appropriate amounts. Generally requires some means of control or regulation to proportion chemicals into the water being treated.

CONTRAINDICATIONS Potential side effects that a drug or preparation may cause in a user.

CONTROL Any device for regulation of a system or component in normal operation, manual or automatic. If automatic, the implication is that it is responsive to changes of pressure, temperature or other property whose magnitude is to be regulated.

CONTROL REFRIGERANT Device used to regulate flow of liquid refrigerant into evaporator, such as capillary tube, expansion valves, high and low side float valves, etc.

CONTROL TEMPERATURE A thermostatic device which automatically stops and starts motor, operation of which is based on temperature changes.

CONTROL VALUE A control value on a water conditioner may be manually or automatically operated and is used to direct the flow of water in a certain direction.

CONTROLLED EVAPORATOR PRESSURE Controlled system which maintains definite pressure or range of pressures in evaporator.

CONVECTION Transference of heat by the circulation of the heated parts of gas or liquid whereby heated portions are lighter and rise vertically.

CONVECTION, FORCED Transfer of heat resulting from forced movement of liquid or gas by means of fan or pump.

CONVECTION, NATURAL Circulation of a gas or liquid due to difference in density resulting from temperature differences.

CONVENTIONAL WATER CLARIFIERS Clarifiers that treat influent flow using several setups: flash mixing and coagulation, flocculation and sedimentation.

CONVERSION FORMULA Hardness minerals, calcium and magnesium, are measured in parts per million (ppm) or grains per gallon (gpg). 17.1 - ppm = 1 gpg, i.e., .10 gpg of hardness +=171 ppm.

COOLING FACTOR L/G (L over G) -Ratio of the pounds of water being circulated per unit time to the pounds of dry air per unit time which are cooling the water.

COOLING LAKE OR POND A type of recirculating cooling system that uses man-made lakes or ponds to dissipate heat.

COOLING POND Large reservoir on inexpensive real estate whereby warm water is cooled as air contacts pond’s relatively large surface area and colder water is either reused or discharged into public waterway.

COOLING RANGE The difference between the warm water temperature to the tower and the cold water temperature leaving the tower. Also referred to as the temperature drop across the tower.

COOLING TOWER A device for the evaporative cooling of water by contact with air. This is achieved partially by an exchange of latent heat resulting from the evaporation of some of the circulating water, and partially by transfer of sensible heat to the air.

COOLING TOWER INSTITUTE (CTI) International Organization of Cooling Tower Engineers, Manufacturers, and Users dedicated to improving the professional technical state of the art. Towards this end, yearly meetings are held, pertinent papers are presented, and technical committees investigate all phases of cooling tower operation to provide a steady exchange of information. Membership and additional information is available at C.T.I., 9030 IH North, Suite #216, Houston, Texas. 77037.

COOLING WATER Any water that removes heat from a point or area of higher temperature and delivers to a point or area of lower temperature.

COORDINATED PHOSPHATE A boiler treatment scheme using phosphate buffers to avoid the presence of hydroxyl alkalinity.

COPPER COMPLEXER A chemical aid used to dissolve copper and prevent its redeposition.

CORE, MAGNETIC Magnetic center of a magnetic field.

CORRATER Electronic device for measuring the corrosion rates, or pitting tendency, of a given metallurgy.

CORRELATION COEFFICIENT A measure of the degree of closeness of the linear relationship between two variables. It is a pure number without units or dimensions, always lies between -1 and +1.

CORROSION The loss of metal through electrochemical reversion to its natural state.

CORROSION COUPON A test metal strip used to determine the rate of corrosion by loss-in-weight.

CORROSION FATIGUE Failure due to repeated, cyclic stressing of a metal in a corrosive environment. This condition results in faster deterioration than would be caused by either cyclic stressing or corrosion alone. In boilers, corrosion fatigue cracking can result from continued breakdown of the protective magnetite film due to cyclic stressing.

CORROSION INHIBITOR Any substance that effectively decreases the corrosion rate when added to an environment in small concentrations.

CORROSION PRODUCTS A result of chemical or electrochemical reaction between a metal and its environment. Note: A corrosion product resulting from the action of water, such as rust, usually consists of insoluble material deposited on or near the corroded area; corrosion products may, however, be deposited a considerable distance from the point at which the metal is undergoing attack.

CORROSIVE Any chemical that causes visible destruction of or irreversible damage to living tissue by chemical action at the site of contact.

COUNTERFLOW In heat exchange between two fluids, opposite direction of flow, coldest portion of one meeting coldest portion of the other.

COUNTERFLOW Tower where air movement and hot water mix at 180§ counter to each other with the air moving vertically through the fill packing and water.

CPSU Consumer Products Safety Commission; federal agency with responsibility for regulating hazardous materials when they appear in consumer goods. For CPSC purposes, hazards are defined in the Hazardous Substances Act and the Poison Prevention Packaging Act of 1970.

CPU Central Processor Unit (computer)

CRACKING An oil-refining process that breaks large molecules into smaller ones.

CREEP Deformation of metals due to stresses below their yield strength. In boiler tubes, creep at elevated temperatures causes longitudinal, discontinuous cracks.

CREVICE CORROSION Corrosion caused by the concentration of dissolved salts, metals, oxygen and other gases. Attack occurs in crevices and pockets remote from the main fluid stream, with a resultant differential cell that ultimately causes deep pitting or cracking.

CRITICAL POINT Of a substance, state point at which liquid and vapor have identical properties; critical temperature, critical pressure and critical volume are the terms given to the temperature, pressure and volume at the critical point. Above the critical temperature or pressure there is not a line of demarcation between liquid and gaseous phases.

CRITICAL PRESSURE The pressure at the critical temperature above which the fluid no longer has the properties of a liquid, regardless of further increase in pressure.

CRITICAL RANGE Temperature range between A₁ and A₃ points. See Transformation Temperature.

CROSS CHARGED Sealed container containing two fluids which together create a desired pressure -temperature curve.

CROSS-CONNECTION The most common causes of cross-connections are a hard water line connected to the soft water line downstream from the softener, a failure of a check valve, gate valve or an open value that should be closed.

CROSS FLOW TOWER A tower in which air movement and hot water mix at 90° FÐ to each other with air moving horizontally through the fill packing and falling water.

CROSS-LINKAGE The reinforcing plastic material that gives the polystyrene matrix dimensional stability and structural integrity. Cross-linkage is usually expressed in percentage. Common cation exchange resin for example, has approximately 8% DVB cross-linkage.

CROSS OVER PIPING (See Header)

CROSS STRUTS (Natural Draft Tower) Framework that holds up the hyperbolic shell, the number of which will vary depending on shell size.

CROSSFLOW Tower where air movement and hot water mix at 90§ or cross to each other with the air moving horizontally through the fill packing and water.

CROSSLINKAGE The degree of bonding of a monomer or set of monomers to form an insoluble tri-dimensional resin matrix.

CRYOGENICS Refrigeration which deals with producing temperatures of 250 F. below zero and lower.

CRYSTAL MODIFIER Chemical that prevents perfect crystals from forming. The deformed crystals do not form hard scale but rather small particles that are easily moved with normal boilerwater.

CSA Abbreviation for Canadian Standards Association.

CUBIC FOOT OF MINERAL The high capacity resin or ion exchange mineral used in the water conditioners is measured and rated in cubic foot lots. For example, one cubic foot of high capacity resin will remove approximately 30,000 grains of hardness minerals before a regeneration is required.

CULTURAL EUTROPHICATION Acceleration by man of the natural aging process of bodies of water.

CUPOLA A furnace for melting scrap or pig iron with coke.

CUPROUS Refers to alloys in which the major constituent is copper. May also refer to monovalent copper ion in solution.

CURRENT (1) Transfer of electrical energy in conductor by means of electrons changing position.

CURSOR The highlighted spot showing the active position of the trace on a computer screen.

CUT-IN Temperature or pressure valve which closes control circuit.

CUT-OUT Temperature or pressure valve which opens control circuit.

CUTANEOUS Skin, through the skin.

CUTANEOUS TOXICITY See "Dermal Toxicity"

CWA Clean Water Act; federal law enacted to regulate/reduce water pollution. Administered by U.S. EPA.

CYCLE A complete course of ion exchange operation. For instance, a complete cycle of cation exchange would involve; exhaustion of regenerated bed, backwash, regeneration and rinse to remove excess regenerant.

CYCLES OF CONCENTRATION Compares dissolved solids in make-up with solids in the circulating water. Since chlorides are soluble, for example, cycle of concentration is equal to ratio of chlorides in circulating water to chlorides in make-up.

CYCLES OF CONCENTRATION This is a numerical expression of the degree to which the soluble mineral salts have been concentrated in a water. It is a direct ratio of the minerals in a system subjected to evaporation and the minerals in the make-up water to that system.

CYCLE OPERATION This refers to sequence of valve operation on automatic softeners. A two-cycle valve is usually one in which up-flow brining is combined with the backwash cycle, sacrificing performance on both backwashing and brining. The five cycle value, such as the Fully Automatic Softener features, performs each essential regeneration step separately and, therefore, under most optimum conditions, provides longer life, more efficient service and better performance.

CYCLONE A device used to separate dust or mist from gas stream by centrifugal force.

D

DALTON’S LAW Vapor pressure exerted on container by a mixture of gases is equal to sum of individual vapor pressures of gases contained in mixture.

DCS Distributed Control System.

DE-SILTING SUMP (Natural Draft Tower) Area in the cold water basin, usually a low point, where any silt can be flushed to a drain.

DEAERATION The process of removing dissolved gases from feedwater in a steam generating system.

DEAERATOR External treatment equipment in which boiler water is heated to 212° F+ for the purpose of releasing dissolved oxygen from the water.

DEALKALIZATION Any process for reducing the alkalinity of water.

DEALKALIZER See Ion Exchange.

DEALLOYING The selective removal of the more active component of an alloy by electrochemical processes.

DEASHING The removal from solution of inorganic salts by means of adsorption by ion exchange resins of both the cations and the anions that comprise the salts. See deionization.

DECANTATION An elutriation process, where the supernatant liquor contains recoverable leaching chemical.

DECARBONATOR A draft degasifier used to remove carbon dioxide.

DECARBURIZATION Loss of carbon from steel due to heating in a medium that reacts with carbon.

DECIBLE Unit of sound level measurement, gauged by converting the pressure energy of noise to electrical impulses and transferring them to a voltmeter calibrated in decibles.

DECK STRINGER Holds the splash bars of the fill deck in a fixed position with respect to air and water flow.

DECOMPOSITION Reduction of the net energy level and change in chemical composition of organic matter because of actions of aerobic or anaerobic microorganisms.

DEFIBRILLATION (Shredding) A condition which develops on the surface of the wood which results in the loosening of the surface fibers when it is rubbed gently with the fingers. The material which is loosened may be an aggregate or individual fibers. Defibrillation is usually an indication of chemical attack rather than biological attack.
The loosening of fibers may also result from crystal formation and alternated freezing and thawing.

DEFROST CYCLE Refrigerating cycle in which evaporator frost and ice accumulation is melted.

DEFROSTING Removal of accumulated ice from cooling element. Thawing frozen foods.

DEFROSTING, HOT-GAS Use of compressor discharge or condenser gas in the evaporator or low side to effect removal of frost.

DEGRADATION A change in a composition of a compound or material to a more stable but undesirable or ineffective form.

DEGREE-DAY Unit that represents one degree of difference from given point in average outdoor temperature of one day and is often used in estimating fuel requirements for a building. Degree-days are based on an average temperature over a 2 hour period. As an example; if an average temperature for a day is 50F., the number of degree-days for that day would be equal to 65F. Or 15 degree-day: (60-50=15). Degree-days are useful when calculating requirements for heating purposes.

DEGREES OF SUB-COOLING The degrees of sub-cooling is a measure of how many degrees the liquid refrigerant is cooled below the saturated refrigerant temperature of boiling point at the condenser pressure.

DEHUMIDIFIER Device used to remove moisture from air in enclosed space.

DEINKING The process of removing ink from secondary fibers.

DEIONIZATION See deashing. Deionization, a more general term than deashing, embraces the removal of all charged constituents or ionizable salts (both inorganic and organic) from solution.

DELAMINATION The separation of the wood into distinct layers or sheets. The separation usually occurs at or near the juncture of spring and summerwood. This condition is usually the result of either high temperatures and/or chemical attack. However, some microorganisms will preferentially attack the springwood and cause this separation.

DELIGNIFICATION The result after some or most of the lignin has been removed from the wood. If the lignin is removed as a result of chemical attack the delignification will be relatively uniform - such as in overchlorination. If it is the result of biological attack, delignification will be localized. Such as, the white pocket rots of oak, cypress, etc. In extreme cases the affected wood will be light cream to white in color.

DELIGNIFICATION (Soft Rot) Loosening of surface fibers of softer lignites causing weakening of timbers or splash bars, reducing members in cross-section and strength.

DEMAND TEST Jar testing to determine the proper coagulant dosage for a given sample.

DEMAND TYPE CONTROL Chemical feed is based on the flow rates of the system being treated.

DEMINERALIZATION Any process used to remove minerals from water; however, commonly the term is restricted to ion exchange processes.

DEMINERALIZING See deashing.

DENITRIFICATION The process involving the facultative conversion by anerobic bacteria of nitrates into nitrogen and nitrogen oxides.

DENSITY The ratio of the mass of a specimen of a substance to the volume of the specimen. The mass of a unit volume of a substance. When weight can be used without confusion, as synonymous with mass, density is the weight per unit volume.

DENSITY The weight of a given volume of exchange material, backwashed and in place in the column.

DEPARTURE FROM NUCLEATE BOILING (DNB) The point where nucleate boiling no longer occurs. Steam bubble generation rate at the tube surface exceeds bubble release rate into the bulk boiler water, leading to larger bubbles and , finally, an insulating steam film.

DEPOSIT Material formed or deposited on a surface in contact with a solution. In cooling, this will be material on surfaces vessels, piping, or related equipment containing the water from which these deposits are derived.

DEPOSIT WEIGHT DENSITY (DWD) The total weight of deposition and corrosion products per unit area, reported in grams per square foot.

DEPOSITION A water borne problem resulting in the accumulation of various solids.

DEPTH FILTRATION Filtration process whereby suspended solid are removed from the influent.

DERMAL Used on or applied to the skin.

DERMAL TOXICITY Adverse effects resulting from skin exposure to a substance. Ordinarily used to denote effects in experimental animals.

DESALTING The removal of salt from crude oil.

DESICCANT Any absorbent or adsorbent, liquid or solid, that will remove water or water vapor from a material. In a refrigeration circuit the desiccant should be insoluble in the refrigerant.

DESIGN CONDITIONS Thermal parameters for which the cooling tower is purchased and/or rebuilt. Expressed as cooling a given GPM flow of water entering the tower at a specified temperature, cooling through a given range leaving the tower at the required temperature and having a designated approach to a stated wet bulb.

DESSICANT Material used to remove moisture from the air.

DETECTOR, LEAK Device used to detect and locate refrigerant leaks.

DEVIATION, STANDARD NORMAL A measure of dispersion of values about a mean value; the square root of the average of the squares of the individual deviations from the mean.

DEW POINT The temperature at which a given mixture of air and water will have a relative humidity of 100% saturation.

DEZINCIFICATION The leaching of zinc from brass, which leaves the metal with a weak porous copper structure, and a reddish, coppery color instead of the yellow color usually associated with brass.

DHHS U.S. Department of Health and Human Services; created in 1980 to replace the Department of Health, Education, and Welfare (DHEW) as "parent" or NIOSH, Public Health Service, and other agencies related to health and safety.

DIAGONAL (Brace) Framework member; any load-bearing member transmitting forces at other than a right angle with references to columns or horizontal ties.

DIALYSIS A separation process depending on differences in diffusion rates of solutes across a permeable membrane.

DIAPHRAGM Flexible membrane usually made of thin metal, rubber or plastic.

DIAPHRAGM METERING PUMP Alternate pumping and suction forces are created in a cavity by the flexing and withdrawal of a diaphragm, or sheet.

DIATOMACEOUS EARTH Fossilized silica remains of diatoms used for industrial waste or filtration applications.

DIATOMS Organisms related to algae, having a brown pigmentation and a silicious skeleton.

DICHLORODIFLUROMETHANE Refrigerant commonly known as R-12. Chemical formula is CC1₂F_2. Cylinder color code is white. Boiling point at atmospheric pressure is -21.62F.

DIFFERENTIAL AERATION CELL An electrical potential generated by differences in the availability of oxygen.

DIFFUSION DECK A fill deck which is located directly under the distribution basin or nozzle bank. The purpose of this deck is to receive water from the basin or nozzle and distribute it uniformly over the fill decks.

DIGESTION Though "aerobic" digestion is used, the term digestion commonly refers to the anaerobic breakdown of organic matter in water solution or suspension into simpler or more biologically stable compounds or both. Organic matter may be decomposed to soluble organic acids or alcohols, and subsequently converted to such gases as methane and carbon dioxide. Complete destruction of organic solid materials by bacterial action alone is never accomplished.

DIGITAL SIGNAL Signal with discrete value, e.g. On or Off, 1 or 0, +5 Volts or 0.2 Volts.

DIODE A two-element electron tube which will allow more electron flow in one direction in a circuit than in the other direction, tube which serves a rectifier.

DIP SWITCH A set of four to eight miniature switches fabricated in a dual inline package (DIP), used for hardware setup (Addresses, Baud Rates, etc.)

DIRECT CURRENT Electron flow which moves continuously in one direction in circuit.

DIRECT DESUPERHEATING Lowering superheated steam by quenching the steam with a quality water spray.

DIRECT EXPANSION EVAPORATOR An evaporator coil using either an automatic expansion valve (AEV) or a thermostatic expansion value (TEV) refrigerant control.

DIRECT FILTRATION PLANTS A chemical-based filtering system that coagulates colloids into filterable suspended solids without the aid of a clarifier.

DISCHARGE STACK A walled enclosure extending upward above the eliminators to direct exhaust air vertically away from fans in a forced draft tower.

DISINFECTION Application of energy or chemicals to kill pathogenic organisms.

DISPERSANT A chemical which causes particulates in a water system to remain in suspension.

DISPERSION A colloidal solution or a uniform suspension.

DISSOCIATION See ionization.

DISSOLVED AIR FLOTATION A process involving the compression of air and liquid, mixing to super-saturation, and releasing the pressure to generate large numbers of minute air bubbles. As the bubbles rise to the surface of the water, they carry with them small particles that they contact.

DISSOLVED GASES Gases dispersed throughout a body of water.

DISSOLVED IRON In water conditioning, iron is usually described as being dissolved or undissolved. The dissolved or ferrous iron is very soluble in most water and the undissolved or ferric iron is almost always insoluble.

DISSOLVED MATTER That matter, exclusive of gases, which is dispersed in water to give a single phase of homogeneous liquid.

DISSOLVED OXYGEN (D.0.) Due to the diurnal fluctuations of dissolved oxygen in streams, the minimum dissolved oxygen value shall apply at or near the time of the average concentration in the stream, taking into account the diurnal fluctuations.

DISSOLVED SOLIDS Solids which are in true solution in water and cannot be removed by filtration. Their presence is due to the solvent action of water in contact with the minerals in the earth.

DISTRIBUTION BOX Used in conjunction with the manifold and valve assembly in a Crossflow Tower to disperse the hot water uniformly in all directions thereby increasing the effectiveness of the distribution nozzles.

DISTRIBUTION RATIO The ratio of amine in the steam to the amine in the condensate at the points of condensation.

DISTRIBUTION SYSTEM Mechanical method of uniformly passing the hot water over the fill area preparatory to cooling. Low pressure spray through piping and nozzles is normally used in counterflow tower, and gravity drop is mainly utilized in crossflow towers.

DISTRIBUTOR An internal piping system to spread flows uniformly through the resin bed. The upper distributor spreads the hard water in the softening position. It also collects the water in the backwash position. The bottom distributor collects the softened water but also distributes the backwash water flow. The bottom distributor is usually called the underdrain. A salt stratifer could be called a "brine distributor".

DISTRIBUTOR Sometimes called strainer. Used within softener tank to distribute the flow of water throughout the tank and also to prevent the resin from escaping into the house lines.

DONNAN EFFECT The rejection of diffusion of external ions by a semipermeable membrane because of a high internal concentration of ions of the same charge.

DOSING PIPETTES Small pipes used in jar testing to transfer the correct chemical solution volume to a dosing vial.

DOSING VIALS Small containers (typical size 25 ml) that hold and dilute chemicals added to a sample for jar testing.

DOT U.S. Department of Transportation; regulates transportation of chemicals and other substances, to aid in the protection of the public as well as fire, law enforcement, and other emergency response personnel, particularly when transportation incidents occur involving hazardous materials. Detailed DOT classification lists specify appropriate warnings-such as Oxidizing Agents or Flammable Liquid-which must be used for various substances.

DOUBLE-FLOW WATER COOLING TOWER A crossflow Tower with two fill sections and one plenum chamber which is common to both.

DOWNCOMERS Tubes situated in a water tube boiler which are not exposed to the flame nor the hottest flue gases. Therefore, the relatively denser and cooler water in the downcomers pushes the warmer water up the risers or steam generating tubes to the steam drum, thus initiating a natural circulation in the boiler.

DOWNFLOW Conventional direction of solutions to be processed in ion exchange column operation, i.e., in at the top, out at the bottom of the column.

DOWNSPOUT A short vertically placed pipe or nozzle used in a gravity distribution system to divert water from a flume or lateral to a splasher.

DPD (DIETHYLPARAPHENYLENEDIAMINE) TEST A testing method to determine free residual and total residual chlorine levels in which the red color that is produced by the reaction of chlorine and iodide is either titrated to a colorless endpoint or is measured on a photometer.

DRAFT A current of air. Referring to the pressure difference which causes a current of air or gas to flow through a flue. Or referring to a localized effect caused by factors of high air velocity, low ambient temperature, or direction of air flow.

DRAIN VALVE (Drain Line) A valve or line used to direct or carry backwash water, spent regenerant and rinse water to the nearest drain of the household waste system.

DRIER A substance or device used to remove moisture from the refrigeration system.

DRIFT Water droplets which are entrained in the airstream as it passes through the tower and are thrown out of the hot air discharge plenum or fan stack. Manufacturers limitations are 2/10ths of 1% allowable, but vary with specifications.

DRIFT ELIMINATORS Baffling that causes discharging hot air with entrained water droplets to change direction a number of times, thereby causing the droplets to hit the eliminator surface and fall back into the tower at every change of direction.

DRIP PROOF MOTOR An open motor in which the ventilating openings are so constructed that drops of liquid of solid particles falling on the motor at any angle not greater than 15 degrees from the vertical cannot enter the motor either directly of by striking and running along a horizontal or inwardly inclined surface.

DRIVE SHAFT A device including a coupling (or couplings) for transmitting torque from the driver to the speed reducer.

DRIVER Primary drive for the fan drive assembly; usually an electric motor.

DROPWISE CONDENSATION The beading of condensate due to the presence of filming amine.

DRY BULB Ambient temperature of air measured in the regular manner with conventional instruments.

DRY ROT A term loosely applied to any dry, crumbly rot but especially to that which, when in an advanced stage, permits the wood to be crushed easily to a dry powder.

DRY-BULB TEMPERATURE The ambient temperature of air registered by the common thermometer.

DRY-SALT TANK A brine tank, usually full of undissolved salt and with saturated brine below the undissolved salt. This type of brine tank is almost always used with automatically regenerated softeners so as to reduce the frequency of the manual refilling with bagged salt. When you look into the brine tank, all you see is undissolved salt, thus, dry-salt.

DRYNESS FRACTION The percentage of steam by weight in the steam-water mixture.

DUAL MEDIA The combining of two different types of filter media to improve the filtration process.

DUCTILE FRACTURE Fracture in which plastic deformation is evident.

DUPLEX PUMP A pump with two (2) pumping heads and a single drive motor.

DUST EXPLOSION PROOF MOTOR An enclosed motor whose enclosure is designed and constructed so as not to cause the ignition or explosion of an ambient atmosphere or the specific dust and also not to cause the ignition of the dust on or around the machine. Class II, Group E, Group F, & Group G.

DYNAMIC SYSTEM An ion exchange operation wherein a flow of the solution to be treated is involved.

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