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R

RADIANT PLATEN HEATER A radiant superheater with tubes arranged in one plane, connecting to inlet and outlet headers. Effectively absorb radiant furnace heat.

RADIATION Heat loss caused by a body warmer than surrounding air giving off its latent heat by flowing thermally "downhill" from the hot body to the cooler area.

RADICAL Elements preferentially bond together into a charged compound that acts like a single ion.

RAG Debris that accumulates at an oil-water interface.

RAKE SPEED The speed at which a sludge rake moves sludge along a clarifier bottom.

RAKE TORQUE The turning force of a sludge rake.

RAM Random Access Memory

RANGE The numerical difference between the water temperature entering the cooling tower at the distribution system and the cold water temperature leaving the sump of the cooling tower.

RANKINE CYCLE The successive changes in heat content and temperature as water is converted to steam, expands through a prime mover, condenses, and returns to the boiler.

RAPID SAND FILTER A filter consisting of a layer of sand or other granular medium, typically 18 to 30 inches thick, and supported by an underdrain system.

RAW WATER Untreated water.

RCRA Resource Conservation & Recovery Act (Federal Hazardous Waste Management Regulations).

RE-USE Water re-use, the subsequent use of water following an earlier use without restoring it to the original quality.

REACTION A chemical transformation or change; the interaction of two or more substances to form new substances.

REACTION FORCE A force exerted in the opposite direction to the direction in which the body exerting the force is moving.

REACTION KINETICS In general, the factors affecting the rates of a reaction.

REACTIVITY A description of the tendency of a substance to undergo chemical reaction with the release of energy. Undesirable effects such as pressure buildup, temperature increase, formation of noxiousm, toxiic, or corrosive by-products may occur because the response of a substance to heating, burning, direct contract with other materials, or conditions of use or storage. A solid waste which exhibits a "characteristic of reality," as defined by RCRA, may be regulated (by EPAA) as a hazardous waste.

RECARBONATION The use of carbon dioxide for stabilization in chemical precipitation softening.

RECEIVING WATERS Rivers, lakes, oceans, or other water courses that receive treated or untreated wastewaters.

RECIPROCATING Action in which the motion is back and forth in a straight line.

RECIRCULATING COOLING WATER Any cooling water system where the water is repeatedly returned to the parts of the system.

RECIRCULATION A phenomenon where the hot exhaust air is forced downward and back into the cooling tower mixing with and lowering the cool fresh inlet air, usually due to design or placement problems. This raises the wet bulb temperature of the entering air above that of the ambient air and greatly reduces tower performances.

RECOVERY FURNACE A furnace which burns black liquor from the draft pulping process, to recover the cooking chemicals as smelt.

RECRYSTALLIZATION Change from one crystal structure to another, which occurs on heating and cooling through a critical temperature.

RECYCLE The return of a quantity of effluent from a specific unit or process to the feed stream of that same unit. This would also apply to return of treated plant wastewater for several plant uses.

RED MUD The gangue from bauxite processing.

REDISTRIBUTION BASIN An elevated basin installed between the hot and cold water basins in a crossflow tower to maintain uniform water distribution throughout the entire height of the fill.

REDOX POTENTIAL Reduction-oxidation potential measured against a standard electrode.

REDUCING AGENT In a reduction reaction (which always occurs simultaneously with an oxidation reaction) the reducing agent is the chemical or substance which combines with oxygen, or loses electrons to the reaction.

REDUCTION A chemical process that involves a gain of electrons.

REFORMED PEARLITE Pearlite in an overheated region which formed because of slow cooling.

REFRIGERANT The refrigerant is the medium used to provide cooling in a vapor compression cooling system.

REFRIGERANT The working fluid in a refrigeration cycle, absorbing heat from a reservoir at low temperature and rejecting heat at a higher temperature.

REFRIGERANT CHARGE Quantity of refrigerant in a system.

REFRIGERANT CONTROL Device which meters refrigerant and maintains pressure difference between high pressure and low pressure side of mechanical refrigerating system while unit is running.

REFRIGERATING SYSTEM A combination of interconnected refrigerant-contained parts in which a refrigerant is circulated for the purpose of extracting heat.

REFRIGERATING SYSTEM, CASCADE One having two or more refrigerant circuits, each with a pressure-imposing element, condenser and evaporator, where the evaporator of one circuit cools the condenser of another (lower temperature) circuit.

REFRIGERATING SYSTEM, COMPOUND One having compressors which are interconnected in series in the same refrigerant system, the discharge of each lower stage compressor being connected to the suction of the next higher-stager compressor, in some cases two or more stages of compression may be contained in a single compressor (internally compounded).

REFRIGERATING SYSTEM, MECHANICAL A refrigerating system employing a mechanical compression device to remove the low pressure refrigerant enclosed in the low pressure side and deliver it to the high pressure side of the system

REFRIGERATING SYSTEM, MULTI-STAGE A refrigerating system, which consists of more than one stage of compression. In general, there are two types of multi-stage systems, compound and cascade.

REFRIGERATION EFFECT The refrigeration effect is the energy transferred to the refrigerant in the evaporator measured in BTU/lb.

REGENERANT The solution used to restore the activity of an ion exchanger. Acids are employed to restore a cation exchanger to its hydrogen form; brine solutions may be used to convert the cation exchanger to the sodium form. The anion exchanger may be rejuvenated by treatment with an alkaline solution.

REGENERATION Restoration of the activity of an ion exchanger by replacing the ions adsorbed from the treated solution by ions that were adsorbed initially on the resin.

REGENERATIVE AIR HEATER An air heater that uses a rotor to transfer heat from the hot gases to incoming air.

REGENERATIVE HEATING In utility stations, a scheme for reducing heat losses to the main condenser in the cycle by using steam extracted from the turbine to heat feedwater. In engineering designs, the use of a heat exchanger to preheat the feed to a process by extracting heat from the product.

REGISTRY OF TOXIC EFFECTS OF CHEMICAL SUBSTANCES A reference published by NIOSH which summarizes toxic characteristics of certain chemicals.

REGRESSION A trend or shift toward a mean. A regression curve or line is thus one that best fits a particular set of data according to some principle.

REHEATER A heat exchanger located in a furnace to increase the temperature of steam extracted from a turbine for reinjection.

RELATIVE HUMIDITY Ratio of amount of water vapor present in air to greatest amount possible at same temperature.

RELAY A solenoid-operated device designed to switch circuits supplying power to motors and other electrical devices.

REMOTE SYSTEM Refrigerating system which has condensing unit located outside and separate from refrigerator cabinet.

REMOVAL EFFICIENCY In the first group of processes, this measurement is the percentage of solid removed from the influent stream; in the second group of process it is the percentage of solid captured in the sludge cake.

REPRODUCTIVE TOXIC Chemicals that affect the reproductive capabilities by producing chromosomal damage (mutations), cause abnormal growth or malformation of fetuses (teratogenesis) or cause toxic effects to reproductive organs.

RESIDUAL HARDNESS See "Hardness Leakage."

RESIDUAL STRESS Stress innate in the metal as produced.

RESIDUAL STRESS Stress present in a body free of external forces or thermal gradients.

RESIN A man-made organic material, usually in bead from, made from petroleum products and sulfonated to give it ion-exchange properties. Softening water is, by far, its most common use.

RESIN BEAD A small round particle of ion-exchange material of 20-50 mesh in size from yellow to brown in color.

RESIN DEGRADATION Physical or chemical deterioration from abrasion, high flow rates or from chlorine or iron.

RESIN FINES Fragmented beads and other resin particles too small to use efficiently.

RESISTIVITY In electronic precipitation, the electrical resistance of one cubic centimeter of dust, in ohm-cm.

RESOLUTION The breaking of an emulsion into its individual components.

RESPIRATORY SYSTEM The breathing system; includes the lungs and the air passages (trachea or "windpipe," larynx, mouth, and nose.

RETORT Sterilization of a food product at greater than 248§ F with steam under pressure.

REVERSE CYCLE DEFROST Method of heating evaporator for defrosting purposes by using valves to move hot gas from compressor into evaporator.

REVERSE DEIONIZATION The use of an anion exchange unit and a cation exchange unit - in that order - to remove all ions from solution.

REVERSE OSMOSIS The physical separation of substances from a water stream by reversal of the normal osmotic process, i.e., high pressure, forcing water through a semi-permeable membrane to the pure water side leaving behind more concentrated waste streams.

REVERSING VALVE Device used to reverse direction the refrigerant flow depending upon whether heating or cooling is desired.

REVERSION Act of changing of a polyphosphate to a stable orthophosphate form.

REVERTED Generally refers to a change of molecularly dehydrated or condensed phosphates (polyphosphates) to a stable orthophosphate form in water.

REYNOLDS NUMBER A dimension grouping of parameters that characterize a fluid’s transition from laminar to turbulent flow.

RINGLEMANN TEST A method of comparing the opacity of a stack plume to an arbitrary set of standard disks of increasing degrees of discoloration.

RINSE The operation which follows regeneration; a flushing out of excess regenerant solution.

RISE VELOCITY The speed at which a particle rises through the surrounding liquid inflotation.

RISER Piping which connects the circulating water supply line from the level at the base of the tower or the supply header to the tower inlet connections.

ROCKWELL HARDNESS ® It is related to the Brinell hardness number but is measured by the depth of penetration by a small, standardized indenter. Several different Rockwell scales for materials of different hardness ranges have been established by selecting various indenter. Several different Rockwell scales for materials of different hardness ranges have been established by selecting various indenter shapes and loads.

ROM Read-Only Memory

ROT Wood destruction by biological organisms that use the wood for food.

ROTAMETER A gauge consisting of a graduated glass tube containing a free float, used for measuring liquid flow.

ROTARY SCREEN A revolving cylindrical screen for the separation of solids from a wastestream.

ROTATING BIOLOGICAL CONTACTOR A waste treatment device involving closely spaced light-weight disks which are rotated through the wastewater allowing aerobic microflora to accumulate on each disk and thereby achieving a reduction in the waste content.

RPM Revolutions per minute

RS232 Port The Electronics Industry Assoc. standard interface for connecting digital equipment to a transmission line.

RUN TIME The run time is the actual operating time in hours per day of the cooling system compressor.

RUST Common designation for the stable ferric oxide product of corrosion of iron and steel.

RYZNAR STABILITY INDEX A practical extension of the Langelier Saturation Index based on experience. This index (always positive) is equal to twice the calculated pH of saturation of CaCO₃ minus the actual pH from test. Index values above 6.5 indicate a corrosive tendency while values below 6.5 indicate a tendency to scale.

S

SAFETY A cooling tower is dangerous. Fan blades can and have killed. A power lockout is mandatory at the fan location. If unavailable, a watch should be established at the power source if it cannot be padlocked out. Initial fan start-up must be visually cleared prior to energizing. Fan, rail, ladder, and louver guards are to be maintained. A Buddy System should be utilized for interior repairs. Primary mandate is simple -use common sense.

SAFETY HANDRAIL Railing around top of tower, platforms and stairways; usually composed of a top handrail, knee-rail and toeboard (depending on location).

SAFETY PLUG Device which will release the contents of a container above normal pressure conditions and before rupture pressures are reached.

SAFETY VALVE (BOILER) A valve connected for coexistence of a vapor and liquid or a vapor and solid phase of the same substance in stable equilibrium. For example, steam over water from which it is being generated.

SALINITY The presence of soluble minerals in water.

SALOMETER A hyrdometer which reads in percent of saturation. 100% on a salometer is about 26% by weight.

SALT Water softener grade. A high grade sodium chloride of a pellet or briquetted type used for regenerating a domestic or household water softener.

SALT DOSAGE The amount of pounds of salt used to regenerate resin, depending on the salt efficiency and soft water quality desired.

SALT SPLITTING The conversion of salts to their corresponding acids.

SALT SPITTING CAPACITY Measures the ability of a resin to split neutral salts as such as sodium sulfate or sodium chloride. For strong base anion resin units in demineralizing systems, it is used to determine the ability of the resin to remove weak acids such as silicic acid or carbonic acid. For dealkalizers, it is used to determine the ability of the resin to remove bicarbonate and carbonate alkalinity. Slat splitting capacity can deteriorate without affecting the total capacity of the resin. Weak base or weak acid resins have no salt splitting capacity.

SAMPLE A small portion of a solution taken from a system for purpose of tests to determine chemical and physical conditions therein.

SAMPLE JARS One-liter beakers or square mixing jars containing water samples for testing.

SAMPLE, COMPOSITE A sample taken at a fixed location by adding together small samples taken frequently during a given period of time.

SAND FILTER Removes the organic wastes from sewage. The wastewater is trickled over a bed of sand. Air and bacteria decompose the wastes filtering through the sand. The clean water flows out through drains in the bottom of the bed. The sludge accumulating at the surface must be removed from the bed periodically.

SAND TRAP Basin in sewage line for collection of high density solids, specifically sand.

SANITARY SEWERS In a separate system, are pipes in a city that carry only domestic wastewater. The storm water runoff is taken care of by a separate system of pipes.

SANITIZING A process that renders a system or object free from human pathogens. Sanitizing, or disinfecting, a system will not kill all bacteria, especially those protected within protozoa or encapsulated in spores. Not to be confused with sterilizing.

SAPONIFICATION The hydrolysis of an ester by an alkali, producing a free alcohol and an acid salt.

SAPWOOD The wood of pale color near the outside of the log. Under most conditions the sapwood is more susceptible to decay than heart wood.

SATURATED WATER Water at a temperature and energy content such that if more energy is added the water begins to boil or vaporize.

SATURATED STEAM Steam that is in equilibrium with water at a particular temperature and pressure.

SATURATION The condition for coexistence in stable equilibrium of a vapor and liquid or a vapor and solid phase of the same substance. Example: Steam over the water from which it is being generated.

SATURATION INDEX See Langelier Index.

SATURATION INDEX The relation of calcium carbonate to the pH, alkalinity and hardness of a water to determine its scale-forming tendency.

SATURATION TEMPERATURE Constant temperature at which boiling occurs.

SAVEALL A general term for several designs of devices used to recover fiber from white water and clarify the water for reuse.

SCALE Any dense, cohesive material that forms a tightly adhering mass on a metallic surface. In cooling water systems, this may include precipitated mineral salts, corrosion products, and/or suspended matter.

SCALE A deposit formed from solution directly in place upon a confining surface. Note: Scale is a deposit that usually will retain its physical shape when mechanical means are used to remove it from the surface on which it is deposited. Scale, which may or may not adhere to the underlying surface, is usually crystalline and dense, frequently laminated and occasionally columnar in structure. Mill scale, formed on iron or steel heated in an atmosphere containing oxygen, consists chiefly of magnetic iron oxide.

SCALE CONTROL Any measure that will prevent or minimize scale deposits.

SCALE PIT A collection chamber alongside a rolling mill that receives roll cooling water containing metallic scale.

SCALING The deposition of materials normally in solution onto heat transfer and other surfaces. Opposed to fouling which is deposition of material normally found in suspension.

SCATTER DIAGRAM A two dimensional plot used to visually demonstrate the relationship between two sets of data.

SCHMUTZDECKE The solids layer that builds up on the filter medium.

SCHRADER VALVE Spring loaded device which permits fluid flow in one direction when a center pin is depressed; in other direction when a pressure difference exists.

SCOURING The removal of surface debris from raw textile fibers.

SCRUBBER Device used after combustion to clean emissions.

SEALED UNIT (See Hermetic System). A motor-compressor assembly in which motor and compressor operate inside sealed dome or housing.

SECOND LAW OF THERMODYNAMICS Heat will flow only from material at certain temperature to material at lower temperature.

SECONDARY AIR In boilers, the air required for completing the combustion process.

SECONDARY FIBERS In the paper industry, fibers reclaimed from waste paper.

SECONDARY pH ADJUSTMENTS Chemically regulating pH levels after clarification.

SECONDARY QUALITY STANDARDS Water quality standards for steps between influent slow and finished water.

SECONDARY SLUDGE A sludge composed primarily of the cell bodies of microorganisms. This sludge is low-density and contains a high percentage of moisture.

SECONDARY TREATMENT The second step in most waste treatment systems in which bacteria consume the organic parts of the wastes. It is accomplished by bringing the sewage and bacteria together in trickling filters or in the activated sludge process.

SEDIMENTATION Gravitational settling of solid particles in a liquid system.

SEDIMENTATION BASIN Any reservoir used for the collection of settled particulate matter (sludge). The two most common types are the rectangular and circular basins.

SEDIMENTATION TANKS Help remove solids form sewage. The wastewater is pumped to the tanks where the solids settle to the bottom or float on top as scum. The scum is skimmed off the top, and solids on the bottom are pumped out to sludge digestion tanks.

SEED A particle or particles, usually crystalline, added to a supersaturated solution to induce precipitation.

SELECTIVE LEACHING Removal of one constituent from a solid alloy by corrosion processes. Common examples of this type of corrosion are dezincification and graphitic corrosion.

SELECTIVITY The order of preference of an ion exchange material for each of the ions in the surrounding aqueous environment.

SELF-CONTAINED BREATHING APPARATUS Protective equipment that supplies fresh air to the used, not filtered air as with a respirator.

SENSIBLE HEAT The "heat you can feel" the heat required to change the temperature of the air or water. Hot water gives up a portion of its heat to the colder air by the heat "flowing downhill" from hot to cold.

SENSIBLE HEAT LOSS A heat transfer that occurs when cooling water is warmer than the surrounding air. In this case there is a tendency for the air to cool the water by taking on its sensible heat.

SENSITIZER A chemical substance or mixture that causes a substantial number of people to develop an allergic reaction in normal tissue after repeated exposure to the chemical or mixture.

SENSITIZATION Increased susceptibility to intergranular corrosion in austenitic stainless steels. A stainless steel that is sensitized can be detected metallographically by prominent grain boundaries. Sensors and pneumatic controllers change fan blade angles to utilize minimum HP depending upon the varying heat rejection load required at any given time. High Energy Saver.

SEQUESTER To form a stable, water-soluble complex.

SEQUESTRATION Formation of a water soluble complex compound.

SEROGROUP A means to identify a specific bacterium within a species. A bacterium from an identified serogroup reacts in a certain fashion with a specific serum, which sets it apart from others of its kind.

SERPENTINE The result of the reaction between magnesium hardness and silica in the presence of alkalinity.

SERVICE RUN Refers to the operating cycle of a water softener during which the hard water passes through the ion exchange resin and enters the service lines as soft water.

SESSILE Permanently attached to a surface and not free to move about - such as a slime mass, within which bacteria dwell.

SETA Setaflash Closed Tester; a flash point test method.

SETTLEABLE MATTER (solids) Determined in the Imhoff cone test and will show the quantitative settling characteristics of the waste sample.

SETTLING TANK Synonymous with "Sedimentation Tank."

SETTLING VELOCITY The speed at which a particle falls through the surrounding liquid in sedimentation.

SEWAGE Waste fluid in a sewer.

SEWERS A system of pipes that collect and deliver wastewater to treatment plants or receiving streams.

SHARP FREEZING Refrigeration at temperature slightly below freezing, with moderate air circulation.

SHELF LIFE The time period in which polymers maintain their optimum activity.

SHELL AND TUBE HEAT EXCHANGER A shell and tube heat exchanger is a heat exchanger designed so that one fluid flows through one or more pipes called the exchanger tubes and the other fluid flows outside of the exchanger tubes but enclosed within a large pipe called the heat exchanger shell.

SHELL DIAMETER (Natural Draft Tower) Diameter of the shell at the top of the curb, measured from inside of cross struts to outside of cross struts.

SHELL HEIGHT (Natural Draft Tower) Dimension from top of curb to top of the hyperbolic shell.

SHELL PASSES The number of shell passes is the number of times the shellside fluid travels the length of a shell and tube heat exchanger. Typically, one shell pass.

SHIELDED CABLE Insulated conductor(s) enclosed within a metalic web. Maintains signal integrity-Analog Inputs.

SHOCK FEED The introduction of a large quantity of chemical treatment into system water within a very short period of time. Term usually used to describe feeding of biocide into cooling tower system.

SHOCK LOAD A quantity of wastewater or pollutant that greatly exceeds the normal discharged into a treatment system, usually occurring over a limited period to time.

SHOP-ASSEMBLED BOILER Boiler assembled in the maker’s facility and shipped, in it assembled form, to the installation site.

SHORT RUN Any quantity of soft water delivered that is less than normal is a short run.

SHOT FEEDER Chemical feed system in which water flow, from high to low pressure side, forces chemicals from a feed tank into the system.

SIC Standard Industrial Classification.

SIDESTREAM FILTRATION The process of filtering a portion of the recirculating water to remove suspended solids before returning the water to the system.

SIGHT GLASS Glass tube or glass window in refrigerating mechanism which shows amount of refrigerant, or oil in system; or, pressure of gas bubbles in liquid line.

SIGNAL CONDITIONING Modifying an input signal to be suitable for use in a system for use in a system, e.g. 0 - 1 mA to 4 - 20 mA input. A pump with a single drive motor and pumping head.

SILICA Common designation for silicon dioxide.

SILICA GEL Chemical compound used as a drier, which has ability to absorb moisture when heated, and moisture is released and compound may be reused.

SILICA LEACHING Condition occurring when hot alkaline water dissolves silica from the sand.

SILICEOUS GEL ZEOLITE A synthetic, inorganic exchanger produced by the aqueous reaction of alkali with aluminum salts.

SILT Insoluble suspended matter in a water. The source may be air-borne dust or entrained soil minerals.

SILVER NITRATE A reagent used to determine chloride content of a water.

SINGLE FLOW WATER COOLING A Crossflow Tower having a fill section on one side of the plenum chamber only.

SIPHONING The natural flow of a liquid from a point of higher pressure to a point of lower pressure.

"SKIN" A notation, sometimes used with PEL or TLV exposure data; indicates that the stated substance may be absorbed through the skin, mucous membranes, and eyes. This additional exposure must be considered part of the total exposure to avoid exceeding the PEL or TLV for that substance.

SKIN SENSITIZER See "Sensitizer."

SKIN TOXICITY See "Dermal Toxicity.

SLAGGING Hard, insulating deposits of metals and salts that hold tenaciously to surfaces within the radiant section of boilers.

SLIME Substances of viscous organic nature usually derived form microbiological growth. Often refers to the total accumulated mass of slime and various trapped insoluble organic and inorganic materials in a water.

SLIME CAPSULE Diffuse and gelatinous capsule surrounding the cell wall of most bacteria. Primarily composed of various forms of ploysaccharides, lipoproteins, and polypetides.

SIMPLEX PUMP A pump with a single drive motor and pumping head.

SLOP OIL A general term in oil refining applying to tramp oil discharge to the oily sewer during shutdown and startup or through abnormal operation.

SLOTTED LATERALS The underdrain laterals, instead of being orificed (drilled _" or 3/16" holes), have many tiny openings (as though they were partially cut with a hacksaw around the perimeter of the pipe.)

SLUDGE A product of decomposition of oil resulting from impurities, moisture or chemical reactions, and favored by excessive temperature. Sludge may be mushy, gummy, or hard.

SLUDGE A water-formed sedimentary deposit. It usually does not adhere sufficiently to retain its physical shape when mechanical means are used to remove it from a surface. Sludge is not always found at he place where it is formed. It may be hard and adherent and baked to the surface on which it has been deposited.

SLUDGE BLANKET A concentrated layer of sludge separating the slurry and the clarified water in a solids contact clarifier.

SLUDGE BLANKET LEVEL The sludge/water interface’s depth below the clarifier surface.

SLUDGE BLOWDOWN Removal of sludge from a unit operation.

SLUDGE CONDITIONING Chemical treatment and mixing of sludge using coagulation and flocculation process.

SLUDGE DEWATERING Process typically used after sludge thickening to further decrease the percentage of liquid to solid. The end result of sludge dewatering is a sludge cake that can be disposed of easily and economically.

SLUDGE DISCHARGE PUMP A pump that siphons sludge from a sedimentation basin.

SLUDGE INVENTORY Am amount of sludge being maintained in the unit operation.

SLUDGE JUDGE A clear, rigid plastic pipe used for sampling and measuring the volume of sludge in a unit operation.

SLUDGE RAKE A mechanical arm that moves sludge along a clarifier bottom.

SLUDGE SAMPLE TAPS Sample valves through which sludge samples are drawn.

SLUDGE THICKENING Processes to increase the concentration of solids in a slurry.

SLUDGE VOLUME INDEX An inverse measure of sludge density.

SLUG A large aggregate of water or foam (as compared to small droplets) which can be carried through the superheater.

SLUG DOSE A slug dose is the addition of a chemical to a system instantaneously so that when completely mixed, the chemical concentration will equal a predetermined amount.

SLUG FEED See Shock Feed.

SLUICING A method of transporting resin from one tank to another wit water. Sluicing is usually employed in mixed bed deionization systems with external regeneration facilities.

SLURRY A solids-water mixture, with sufficient water content to impart fluid handling characteristics to the mixture.

SLURRY SOLIDS The sludge in a given clarifier zone.

SMELT Molten slag; in the pulp industry, the cooking chemicals tapped from the recovery boiler as molten material and dissolved in the smelt tank as green liquor.

SODA ASH A common water treating chemical, sodium carbonate.

SODIUM ABSORPTION RATION (SAR) In irrigation water, a relationship between sodium and hardness used to predict acceptability for both the plant and soil being irrigated.

SODIUM CYCLES Cation exchange where calcium and magnesium are exchanged with sodium ions. Ion exchange resin is regenerated by a solution of sodium chloride, salt.

SODIUM HYDROSULFITE The chemical compound best suited to remove iron from iron-fouled resin. It is the principal ingredient of packaged, resin cleaners. It may be purchased from chemical supply houses in its generic form.

SODIUM ZEOLITE A cation exchange resin, regenerated with salt, which exchanges sodium ions for calcium and magnesium ions in the water being treated. Other ions such as iron and strontium will also be exchanged.

SOFT WATER Water containing less than 1 grain per gallon of dissolved calcium and magnesium hardness minerals. This is a Water Conditioning Foundation specification and F.H.A. standard.

SOFFIT (Natural Draft Tower) The underside of the ring beam, forming the bottom part of the hyperbolic shell. Generally it is thick at the base and is the first portion of the shell above the cross struts.

SOFT ROT A term which has gained common usage in the cooling water field. This term is used to describe that type of biological attack which is restricted to the surface such as the surface attack in the flooded sections of the lower and the surface in some drift eliminator sections. In fields other than the cooling industry the term soft rot has a different meaning. This type of attack is usually caused by organisms other than the Basidiomycetes.

SOFTENING The act of removing all or part of the hardness constituents from a water solution.

SOLENOID VALUE Electromagnet with a moving core which serves as a value, or operates a value.

SOLID ABSORBENT REFRIGERATION Refrigerating system which uses solid substance as absorber of the refrigerant during cooling part of cycle and releases refrigerant when heated during generating part of cycle.

SOLO VALVE A trademarked product of Aquamatic, Inc., in Rockford, IL. It is a manual, three-position, lift-turn, multiport softener control valve operated by a single lever.

SOLUBILITY The amount of a substance that can be dissolved in a solution under given conditions.

SOLUBILITY CURVE A graphical representation of the degree of solubility of a material with respect to one defined variable.

SOLUBILITY IN WATER A term expressing the percentage of a material (by weight) that will dissolve in water at ambient temperature. Solubility information can be useful in determining spill cleanup methods and fire-extinguishing agents and methods for a material. Terms used to express solubility are: Negligible Less than 0.1 percent Slight 0.1 to 1.0 percent Moderate 1 to 10 percent Appreciable More than 10 percent Complete Soluble in all proportions

SOLUTE The component of a solution which is present in the greatest proportion.

SOLUTION Any liquid containing dissolved matter.

SOLVENT The component of a solution which is present in the greatest proportion.

SOOT BLOWING Process where steam is directed across the fireside boiler tube surfaces to blow soot and other combustion products from the tubes.

SOUR WATER Waste waters containing malodorous materials, usually sulfur compounds.

SOURCE The stream, river, lake or well that supplies influent water.

SO_x Oxides of sulfur; undesirable air pollutants. SO_x emmisions are regulated by U.S. EPA under the Clean Air Act.

SPARGING Introducing air or gas into a liquid.

SPARKING In electrostatic precipitation, the electrical sparks that travel from the discharge wire to the grounded plate.

SPATIAL AVERAGE The mean value of a set of observations distributed as a function of position.

SPDT SWITCH Single-pole, double-throw switch.

SPECIES A biological type; on MSDS, species refer to the test animals, usually rate, mice, or rabbits, which were used to obtain the toxicity test data reported.

SPECIFIC CONDUCTANCE A measure of the ability of water to conduct an electric current, expressed as micromhos per cubic centimeter. A micromho is a millionth of a mho, which in turn is the reciprocal of an ohm resistance.

SPECIFIC GRAVITY Weight of a liquid compared to water which is assigned value of 1.0.

SPECIFIC HEAT Ratio of quantity of heat required to raise temperature of a body one degree to that required to raise temperature of equal mass of water one degree.

SPECIFIC VOLUME Volume per unit mass of a substance.

SPECTROPHOTOMETRIC The use of sensitive instrumentation to measure color changes in a sample after addition of a reagent, rather than visual comparison with a standard.

SPEED REDUCER A device to change speed of the driver to the speed desired for the fan.

SPHERICITY Relating to the spherical nature and whole bead content of a resin.

Spheroidite Aggregate of iron or alloy carbides, mainly spherical in shape and dispersed throughout a matrix of ferrite.

SPLASH BAR Horizontal component of a fill deck in a tower which constitutes the principal splash surface.

SPLASHER Used in a gravity distribution system to receive water from a downspout and effect uniform spreading of the water over the wetted area of the tower.

SPLIT STREAM SOFTENING The use of sodium zeolite and hydrogen zeolite softeners in parallel produces a soft water effluent with a controlled alkalinity level. This is sometimes referred to as dealkalization.

SPM Strokes per minutes

SPORE A reproductive cell, or seed, of algae, fungi, or protozoa.

SPRAY FILLED WATER COOLING TOWER A tower which has no fill. Water to air contact depends entirely on the break-up of the water by means of pressure spray nozzles.

SPRAY NOZZLE Device used in a distribution system to break up the flow of the circulating water into droplets and effect uniform spreading of the water over the wetted area of the tower.

SPRAY POND A cooling pond in which cooling water is sprayed into the surrounding air to increase the rate of evaporation.

STABILITY An expression of the ability of a material to remain unchanged. For MSDS purposes, a material is stable if it remains in the same form under expected and reasonable conditions of storage or use. Conditions which may cause instability (dangerous change) are stated for example, temperature above 150° F, or shock from dropping.

STABILITY INDEX An empirical modification of the Saturation Index used to predict scaling or corrosive tendencies in water systems.

STABILIZATION When a material is dispersed and does not settle, it is considered stabilized.

STABILIZED SUSPENSION A solid-in-liquid suspension caused by small, unsettleable particles that are held apart by the repellent action of their anionic charges.

STABILIZING Act of keeping a water from changing particularly with respect to its mineral content. Example: preventing the precipitation of calcium carbonate.

STAGGERING Avoiding two or more softeners from regenerating at the same time when regeneration is initiated by time-clock, meter, sensor or counter. The operator must control initiation times by keeping them as far apart as possible unless an electrical interlock has been provided.

STRAINER A screen to remove matter that would otherwise cause plugging or deposits.

STANDARD AIR Has a density of 0.075 lb. per cu. ft., which is air at 68§ F DBT, 50 percent RH and 29.92 in. HG (and substantially equivalent to 70§ F dry air).

STANDARD DEVIATION A statistical measure of the spread or variation of individual measurements.

STANDARD SOLUTION Solution with an accurately known concentration which is used to make up less concentrated solutions.

STATE, GASEOUS One of three states or phases of matter characterized by greatest freedom of molecules and lack of any inherent fixed shape or volume.

STATE, LIQUID One of three states or phases of matter characterized by limited freedom of molecules and by substantial incompressibility.

STATE, SOLID One of the three states or phases of matter characterized by stability of dimensions, relative incompressibility, and molecular motion held to limited oscillation.

STATIC PRESSURE DROP Reduction of air movement through the tower due to the resistance of internal components such as air intake louvers, fill packing, water distribution system, internal supporting beams, drift eliminators, fan stack configuration.

STATIC SYSTEM The batch-wise employment of ion exchange resins, wherein (since ion exchange is an equilibrium reaction) a definite endpoint is reached involving fixed ratios of ion distribution between the resin and solution.

STEAM BLANKETING A condition which permits stratified flow of steam and water, usually occurring in low heat input zones, such as horizontal and roof tubes.

STEAM DRUM Upper drum in a boiler circuit that separates water/steam mixture and releases steam.

STEAM PURITY A measure of the concentration of dissolved and entrained solids in the steam.

STEAM QUALITY The percent water present in the steam.

STEAM TRACING Using small diameter piping enclosed in an insulating envelope alongside larger process piping to maintain minimum temperature.

STEAM TRAP A device that traps steam but allows condensate to pass through.

STEAM TURBINE CONDENSER A heat exchanger, generally of the shell and tube type, used to condense low pressure exhaust steam from a turbine.

STEAMSIDE BURNING A chemical reaction between steam and the tube metal at high temperatures.

STEL Short-Term Exposure Limit; ACGIH terminology. See "TLV-STEL."

STERILE A process that renders an object or solution free of all organisms. Not to be confused with pasteurization.

STICKWATER The distillate produced in the cooking of meat or in the rendering of fat and scraps.

STIFF-DAVIS INDEX An index used to predict the stability of brackish waters, such as those used in waterflooding.

STOICHIOMETRIC The ratio of chemical substances reacting in water that corresponds to their combining weights in the rheoretical chemical reaction.

STROKERS Mechanical devices that burn solid fuels in a bed at the bottom of a furnace. They convert chemical energy in the fuel to thermal energy that is absorbed by boiler surfaces to generate steam or produce high-temperature water.

STOKES’ LAW An expression for calculating the rate of fall of particles through a fluid based on densities, viscosity, and particle size.

STRAIN A measure of a change in the size or shape of a body, referenced to its original size or shape.

STRATIFIED BED The use of two separate layers of resins in the same ion exchange unit. The resins will be of the same type; i.e., cation or anion. By combining resins, improved operating efficiency can be realized. In anion units, one of the resins may be used as an organic trap to protect the other resin.

STRAY CURRENT CORROSION Corrosion resulting from direct current flow through a path other than the intended circuit. For example, by any extraneous current in the earth.

STRESS Force per unit area, often thought of as a force acting through a small area within a plane.

STRESS CORROSION CRACKING (SCC) A sudden, catastrophic brittle failure of a normally ductile metal, resulting from the interaction of tensile stress and a corrosive environment.

STRESS RELIEVING Method to reduce residual stresses in a metal by heating to a suitable temperature and slowly cooling.

STRICT (OBLIGATE) ANAEROBE An organism that grows only in the absence of free oxygen.

STRONG ACIDIC CATION RESIN These resins are used in sodium zeolite and hydrogen zeolite softeners. They are used in hydrogen zeolite softeners associated with deionization systems. When regenerated with salt, the sodium ions on the resin will effectively exchange for divalent cations such as calcium and magnesium. When regenerated with acid, the resin will spit neutral salts converting the salt to its corresponding acid. The resin usually receives its exchange capability from sulfonic grouping.

STRONGLY BASIC ANION RESINS These resins are used in chloride-anion dealkalizers and desilicizers. They are also used in anion units associated with deionization systems. When regenerated with salt, the chloride ions on the resin will exchange for bicarbonate and sulfate anions in the water. When regenerated with caustic, the resin will remove acids, even weak acids, such as carbonic and silicic. The resin usually receives its exchange capability from quaternary ammonium grouping.

SUBCOOLING Process of cooling refrigerant below condensing temperature, for a given pressure. Also cooling a liquid below its freezing point, where is can exist only in a state of unstable equilibrium.

SUBFILL Gravel or anthracite bed that supports the lower distributors in an ion exchange shell.

SUBSIDENCE Removal of suspended matter under conditions of quiescent settling. Rate of settling depends upon the specific gravity, shape and size of the particles, the viscosity of the water and upon currents within the containing basin.

SUCTION LINE The tube or pipe which carries the refrigerant vapor from the evaporator to the compressor inlet.

SUCTION PRESSURE CONTROL VALUE Device located in the suction line which maintains constant pressure in evaporator during running portion of cycle.

SUCTION SCREEN Screen over water sump or pump suction pit on tower cold water basin, prevents debris from entering pump and piping system.

SULFATE-REDUCING BACTERIA (SRB) Group of anaerobic bacteria that can reduce sulfate to sulfide, producing hydrogen sulfide.

SULFONIC A specific acidic group (SO₃H) on which depends the exchange activity of certain cation exchange resins.

SULFUR ACTIVE AGENT A substance possessing stabilization characteristics tending to minimize deposition of calcium carbonate scale, such as a polyphosphate.

SULFUR DIOXIDE A gaseous oxide of sulfur. Forms mild sulfurous acid in water solution.

SULFUR TRIOXIDE A white fibrous solid. Forms sulfuric acid from which it can be pumped. Sometimes used synonymously with cooling tower basin.

SUMP Depressed section of the cold water collecting basin where the cooled water is returned to the heat source, be it the condensors, compressors, or process water equipment.

SUPERHEATED A heat exchanger located in a furnace to increase the temperature of steam leaving the boiler drum.

SUPER HEATED STEAM Steam removed from boiling water and heated further. Temperature rises above saturation temperature and becomes superheated.

SUPERNATANT Liquid floating above settled solids.

SUPERNATE The liquid overlying the sludge layer in a sedimentation vessel.

SUPERSATURATED Refers to a solution or water system that contains one or more dissolved compounds in excess of their normal solubility limit.

SUPPLY HEADER Portion of the water supply system from which riser or inlet connection receives the circulating water flow.

SURFACE BLOWDOWN The draining of boiler water from a skimmer line positioned within the steam drum.

SURFACE FILTRATION Filtration process whereby a filter medium is used to trap solids for mechanical removal.

SURFACE RESISTIVITY The electrical resistance of the fly ash particle’s outer shell.

SURFACE WASHING Cleaning technique to agitate surface sludge via high pressure water-outlets located above the bed.

SURFACE ROT Biological wood attack that is active at the surface.

SURFACE TENSION A property arising from molecular forces of the surface film of all liquids which tends to alter the contained volume of liquid into a form of minimum superficial area.

SURFACE-ACTIVE AGENT A substance possessing stabilization characteristics tending to minimize deposition of calcium carbonate scale, such as a polyphosphate.

SURFACTANT A surface active agent; usually an organic compound whose molecules contain a hydrophilic group at one end and a lipophilic group at the other.

SUSPENDED SOLIDS Materials dispersed in the water which can be removed with filters.

SUSPENSION Foreign particles carried in a liquid but not dissolved in it, like rusty iron in water.

SWEATING This term is used two different ways in refrigeration work: 1) Condensation of moisture from air on cold surface. 2) Method of soldering in which the parts to be joined are first coated with a thin layer of solder.

SWEET WATER CONDENSER A heat exchanger that cools a portion of generated steam so it can be used for attemperating.

SWELLING The expansion of an ion exchange bed which occurs when the reactive groups on the resin are converted into certain forms.

SYNERGISM The combined action of several chemicals which produces an effect greater than the additive effects of each.

SYNERGISTIC A system in which the total effect is greater than the sum of the two effects taken independently.

SYNONYM Another name or names by which material is know. Methyl alcohol, for example, is also known as methanol, or wood alcohol.

SYSTEM, FLOODED A refrigerating system in which only part of the refrigerant passing over the heat transfer surface is evaporated, and the portion not evaporated is separated from the vapor and recirculates.

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