All Terms 5 Flashcards
SACRIFICIAL ANODES
Coupling of a more active metal to a structure resulting in a galvanic current flow through the corroding electrolyte.
SACRIFICIAL PROTECTION
Reduction of corrosion of a metal in an electrolyte by galvanically coupling it to a more anodic metal. A form of cathodic protection.
SADDLE VALVE (TAP
A
LINE)
Valve body shaped so it may be silver brazed or clamped onto a refrigerant tubing surface.
SADDLE VALVE (TAP
A
LINE)
Valve body shaped so it may be silver brazed or clamped onto a refrigerant tubing surface.
SAFETY CAN
Approved container of not more than 5 gallon capacity. It has a spring closing lid and spout cover. It is designed to relieve internal pressure safely when exposed to fire.
SAFETY CONTROL
Device to stop refrigerating unit if unsafe pressure and/or temperatures and/or dangerous conditions are reached.
SAFETY PLUG
Device which will release the contents of a container before rupture pressures are reached.
SALINITY
A measure of the concentration of dissolved mineral substances in water.
SALT SPITTING
The ability of an anion exchanger to convert a salt solution to caustic
SATURATED AIR
When the air cannot hold any more moisture.
SATURATED LIQUID
A liquid which is at saturation pressure and saturation temperature
SATURATED VAPOR
A vapor which is at saturation pressure and saturation temperature. A saturated vapor cannot be superheated as long as it is in contact with the liquid from
SATURATION
Condition existing when substance contains all of another substance it can hold for that temperature and pressure.
SATURATION INDEX
The relation of calcium carbonate to the pH, alkalinity, and hardness of a water to determine its scale forming tendency.
SATURATION PRESSURE
The point, where at a given temperature a pure substance starts to boil.
SATURATION TEMPERATURE
The point, where at a given pressure a pure substance starts to boil.
SAYBOLT UNIVERSAL VISCOSITY
A commercial measure of viscosity expressed as a time in seconds required for 60 mL of a fluid to flow through the orifice of the standard Saybolt
universal viscometer at a given temperature under specific conditions
used for the lighter petroleum products and lubrication oils.
SCALE
Surface oxidation, consisting of partially adherent layers of corrosion products, left on metals by heating or casting in air or in other oxidizing atmosphere. Also a deposit on a
heat
transfer surface resulting from precipitation of salts present in water in contact with that surface, forming a hard, dense material.
SCALE CAUSING ELEMENTS
Calcium and magnesium elements forming scale.
SCALE REMOVAL
Waterside, removal of scale using either the mechanical, the water treatment or the acid cleaning process.
SCC
Stress corrosion cracking.
SCREENS
Equipment designed to prevent larger objects to enter water treatment system.
SCREW PUMP
Compressor constructed of two mated revolving screws.
SCRUBBER
An apparatus for the removal of solids from gases by entrainment in water.
SEAL, MAGNETIC
A seal that uses magnetic material, instead of springs or bellows, to provide the closing force.
SEAL, ROTARY
A mechanical seal that rotates with a shaft and is used with a stationary mating ring.
SECOND LAW OF THERMODYNAMICS
Heat will flow only from material at higher temperature to material at lower temperature.
SECONDARY REFRIGERANT
Chilled liquid
SECONDARY SYSTEM
A re
circulating water system that is a takeoff from a primary system
it does not circulate directly through the source of heat or cooling but only indirectly
SECONDARY TREATMENT
Treatment of boiler feedwater or internal treatment of boiler water after primary treatment.
SEDIMENTATION
Gravitational settling of solid particles in a liquid system.
SEEBECK EFFECT
When two different adjacent metals are heated, an electric current is generated between the metals.
SENSIBLE HEAT
Heat which causes a change in temperature of a substance.
SENSIBLE HEAT
Sensible heat is any heat transfer that causes a change in temperature. Heating and cooling of air and water that may be measured with a thermometer is sensible heat.
SENSIBLE HEAT FACTOR
The ratio of sensible heat to total heat.
SENSING DEVICE
A device that keeps track of the measured condition and its fluctuations so that when sufficient variation occurs it will originate the signal to revise the operation of
SENSING ELEMENT
The first system element or group of elements. The sensing element performs the initial measurement operation.
SEPARATOR
A tank type pressure vessel installed in a steam pipe to collect condensate to be trapped off and thus providing comparatively dry steam to the connected machinery.
SEPARATOR
Device to separate one substance from another.
SEQUENCER
A mechanical or electrical device that may be set to initiate a series of events and to make the events follow in sequence.
SEQUESTER
To form a stable, water
SEQUESTRANT
A substance that holds a mineral or metal in solution beyond its saturation point.
SERIES CIRCUIT
One with all the elements connected end to end. The current is the same throughout but the voltage can be different across each element.
SERVICE DROP
The overhead service wires that serve a building.
SERVICE SWITCH
Disconnect switches or circuit breakers. Purpose is to completely disconnect the building from the electric service.
SERVICE VALVE
Manually operated valve mounted on refrigerating systems used for service operation.
SET POINT
The value of the controlled condition at which the instrument is set to operate.
SETTLING BASIN
A containment design with external water treatment to settle sediments and to clarify.
SHAFT SEAL
Device used to prevent leakage between shaft and housing.
SHARP FREEZING
Refrigeration at temperatures slightly below freezing, with moderate air circulation.
SHED
To de
SHED MODE
A method of demand control that reduces kW demand through shedding and restoring loads.
SHELL AND TUBE FLOODED EVAPORATOR
Device which flows water through tubes built into cylindrical evaporator or vice versa.
SHELL TYPE CONDENSER
Cylinder or receiver which contains condensing water coils or tubes.
SHELL
AND
TUBE
Designation of a heat exchanger having straight tubes encased inside a shell.
SHIELDED CABLE
Special cable used with equipment that generates a low voltage output. Used to minimize the effects of frequency “noise” on the output signal.
SHOCK DOSAGE
The feeding of treatment to a system all in one slug or dose rather than gradually (also called a slug dosage).
SHOCK FEEDER
A device which is used to add treatment to a system in an instantaneous manner.
SHORT CIRCUIT
A direct connection of low resistive value that can significant alter the behavior of an element or system.
SHORT CYCLING
Unit runs and then stops at short intervals
SHROUD, TURBINES
Also referred to as the sealing strip on turbine blades. Its purpose is to supply rigidity to the blades, lessen vibration and provide sealing between stages.
SHROUD, PUMPS
The front and/or back of an impeller.
SHUNT
A device to divert part of an electric current.
SIGHT GLASS
Glass tube or glass window in refrigerating mechanism. It shows amount of refrigerant or oil in system and indicates presence of gas bubbles in liquid line.
SILICA
Silicon dioxide (Si02), a mineral found naturally as quartz or in complex combination with other elements such as silicates.
SILICA GEL
Absorbent chemical compound used as a drier. When heated, moisture is released and compound may be reused.
SILICA, COLLOIDAL
Silica in colloidal form.
SILICA, VOLATILE
Silica carryover with steam.
SILT DENSITY INDEX
A measure of the tendency of a water to foul a reverse osmosis membrane, based on time flow through a membrane filter at constant pressure.
SIMPLE CYCLE
Referring to the gas turbine cycle consisting only of compression, combustion and expansion.
SINGLE PHASING
The condition when one phase of a multiphase (poly
SINGLE SHAFT GAS TURBINE
A gas turbine arrangement in which the compressor and the gas turbine are all coupled to one shaft.
SINGLE STAGE COMPRESSOR
Compressor having only one compressive step between inlet and outlet.
SKIN CONDENSER
Condenser using the outer surface of the cabinet as the heat radiating medium.
SLIME
A soft, sticky, mucus
SLING PSYCHROMETER
Measuring device with wet and dry bulb thermometers. Moved rapidly through air it measures humidity.
SLUDGE
A deposit on a heat
SLUG
A unit of measure for mass in the English system, which equals 14.6 kg in the SI system.
SLUGGING
Condition in which mass of liquid enters compressor causing hammering.
SLURRY
A water containing high concentration of suspended solids, usually over 5000 mg/L.
SLURRY EROSION
Material removal due to the combined action of corrosion and wear.
SODA ASH
A common water treatment chemical, sodium carbonate.
SODIUM CHLORIDE
Common table salt, used to produce a brine solution, used a secondary refrigerant.
SODIUM SULFITE (Na2S03)
A chemical used with water treatment to remove small amounts of oxygen.
SODIUM TRACER METHOD
A technique used to measure dissolved solids in steam to values as low as 0.001 ppm.
SODIUM ZEOLITE SOFTENING
The process of removing scale forming ions of calcium and magnesium and replacing them with the equivalent amount of sodium ions.
SOFT WATER
Water that is free of magnesium or calcium salts.
SOFTENING
The removal of hardness (calcium and magnesium) from water.
SOLAR HEAT
Heat created by visible and invisible energy waves from the sun.
SOLENOID VALVE
Electromagnet with a moving core. It serves as a valve or operates a valve.
SOLID ABSORBENT REFRIGERATION
Refrigeration system which uses solid substance as absorber of the refrigerant during the cooling part of the cycle and releases refrigerant
SOLID STATE HALOGEN LEAK DETECTOR
An electronic leak detector for all halogen. related refrigerants.
SOLUBLE IRON
Usually present in cooling water systems and can arise from metallurgical corrosion.
SOLU
BRIDGE
SORBENT
See absorbent.
SOUR GAS
A gaseous environment containing hydrogen sulfide and carbon dioxide in hydrocarbon reservoirs.
SOUR WATER
Waste water containing malodorous materials, usually sulfur compounds.
SPARGER
An extension into the bottom of a tank of a pipe which has a distribution nozzle on the end for mixing one fluid with another.
SPECIFIC CONDUCTANCE
Measures the ability of a water to conduct electricity. Conductivity increases with total dissolved solids and is therefore used to estimate dissolved solids
SPECIFIC GRAVITY
The density of a substance compared to the density of a standard material such as water.
SPECIFIC HEAT
Ratio of quantity of heat required to raise temperature of a body 1 degree to that required to raise temperature of equal mass of water 1 degree.
SPECIFIC HEAT (Cp)
The ratio of the mount of heat required to raise a mass of material 1 degree in temperature to the amount required to raise n eual mass of reference substance,
SPECIFIC HUMIDITY
Ratio of weight of vapor to the weight of gas in a unit volume of an air
SPECIFIC VOLUME
Volume per unit mass of a substance.
SPLASH SYSTEM, OILING
Method of lubricating moving parts by agitating or splashing oil in the crankcase.
SPLIT
STREAM DEALKALIZER
SPRAY CARRYOVER
Are referred to a mist or fog and are a degree of atomization of the boiler water and carried with the steam. This type of carryover is to be prevented by the drum
SPRAY COOLING
Method of refrigerating by spraying expendable refrigerant or by spraying refrigerated water.
SPRAY MANIFOLD
A pipe, or extension of a water line, that has several openings fitted with nozzles which spray water.
SPRAY
COIL UNIT
SPRAY
COOLING CIRCUIT
An open cooling
water circuit which sprays water and cools by evaporation, for example, a cooling tower, all evaporative condenser, an air washer, or a
spray
coil unit.
STABILITY INDEX
An imperical modification of the saturation index used to predict scaling or corrosive tendencies in water systems.
STANDARD AIR CONDITIONS
Standard air density has been set at 0.075 Ib/cu ft. This corresponds approximately to dry air at 70°F and 29.92 in Hg. In metric units, the standard air
STANDARD CONDITIONS
The standard conditions referred to in environmental system work for air are: dry air at 70°F and at an atmospheric pressure of 29.92 inches mercury (in Hg).
STATE
Refers to the form of a fluid, either liquid, gas or solid. Liquids used in environmental systems are water, thermal fluids such as ethylene glycol solutions, and refrigerants in the
liquid state. Gases are steam, evaporated refrigerants and the air
water vapor mixture found in the atmosphere. Some substances, including commonly used refrigerants, may exist in any
STATIC HEAD
The pressure due to the weight of a fluid above the point of measurement.
STATIC SUCTION HEAD
The positive vertical height in feet from the pump centerline to the top of the level of the liquid source.
STATIC SUCTION LIFT
The distance in feet between the pump centerline and the source of liquid below the pump centerline.
STEAM
Water in vapor state.
STEAM DRUM
A pressure chamber located at the upper extremity of a boiler circulatory system, in which the steam is generated in the boiler and separated from the water.
STEAM JET REFRIGERATION
Refrigerating system which uses a steam venturi to create high vacuum (low pressure) on a water container causing water to evaporate at low
STEAM PURITY
Refers to all matter but water in the steam.
STEAM QUALITY
The percentage by weight of vapor in a steam and water mixture.
STEAM
ABSORPTION CONDENSER
That part of a steam
absorption machine in which the water refrigerant is condensed by cooling
STEAM
ABSORPTION MACHINE
A refrigeration or air
conditioning machine which uses, as a refrigerant, water evaporated by absorption in a brine regenerated by steam and
condensed by cooling
tower water.
STICTION (STATIC FRICTION)
Resistance of start of motion.
STOICHIOMETRIC
The ratio of chemical substances reacting in the water that correspond to their combining weights in the theoretical chemical reaction.
STRESS RAPTURE
A general type of damage referring to carbon steel tubing, when heated above 450°C. Material will plastically deform (creep) and then rapture.
STUFFING BOX
That portion of the pump which houses the packing or mechanical seal, The stuffing box is usually referred to as the dry portion of the pump, and is located in back of
SUBCOOLING
The difference between the temperature of a pure condensable fluid below saturation and the temperature at the liquid saturated state, at the same pressure.
SUBCOOLING
The process of cooling a liquid to a temperature below its saturation temperature for any given saturation pressure.
SUBLIMATION
A change of state directly from solid to gas without appearance of liquid.
SUBLIMATION
Condition where a substance changes from a solid to a gas without becoming a liquid.
SUCTION HEAD
The positive pressure on the pump inlet when the source of liquid supply is above the pump centerline.
SUCTION LIFT
The combination of static suction lift and friction head in the suction piping when the source of liquid is below the pump centerline.
SUCTION LINE
Tube or pipe used to carry refrigerant gas from evaporator to compressor.
SUCTION PRESSURE
Pressure in low
SUCTION PRESSURE CONTROL VALVE
Device located in the suction line which maintains constant pressure in evaporator during running portion of cycle.
SUCTION PRESSURE CONTROL VALVE
Device located in the suction line which maintains constant pressure in evaporator during running portion of cycle.
SUCTION SERVICE VALVE
Two
SUCTION SIDE
Low
SULFATE
A compound, ion, or salt of sulfur and oxygen, such as sodium sulfate (Na2S04).
SULFITE DECOMPOSITION
Sodium sulfite, which is used as an oxygen scavenger, may decomposes with higher temperatures and concentration. The decomposition results in
SULFONIC
A specific acidic group (SO3H) on which depends the exchange activity of certain cation adsorbents.
SULFUR DIOXIDE (SO2)
An old refrigerant.
SUN EFFECT
Solar energy transmitted into space through windows and building materials.
SUPERHEAT
The heat added to a fluid above its saturation point.
SUPERHEATED STEAM
Steam heated above its saturation temperature.
SUPERHEATED VAPOR
A vapor which is not about to condense.
SUPERHEATER
Heat exchanger arranged to take heat from liquid going to evaporator and using it to superheat vapor leaving evaporator.
SUPERHEATING
The process of adding heat to a vapor in order to raise its temperature above saturation temperature. It is impossible to superheat a saturated vapor as long as it is in
contact with the liquid from which it is being generated
hence the vapor must be led away from the liquid before it can be superheated.
SUPERSATURATED SOLUTION
A solution of a salt or mineral with a concentration beyond the normal saturation point.
SURFACE BLOWDOWN
Removal of water, foam, etc. from the surface at the water level in a boiler.
SURFACE HEATING
The exterior surface of a heating unit. Extended heating surface (or extended surface), consisting of fins, pins, or ribs which receive heat by conduction from the
SURFACE
SPRAY UNIT
A spray
coil unit.
SURFACTANT
A compound that affects interfacial tension between two liquids. It usually reduces surface tension.
SURFACTANTS
A wetting agent used to prevent fouling, mainly in water cooling systems.
SURGE
The sudden displacement or movement of water in a closed vessel or drum.
SURGE SURPRESSOR
A device that reduces harmonic distortion in line voltage circuits by clipping off transient voltages which are fed through the power lines from operating
SURGE TANK
Container connected to the low
SUSPENDED SOLIDS
Un
SWAMP COOLER
Evaporative type cooler in which air is drawn through porous mats soaked with water.
SWELLING
The expansion of an ion
SYNERGISM
The combined action of several chemicals which produce an effect greater than the additive effects of each.
SYSTEM
A series of ducts, conduits, elbows, branch piping, etc. designed to guide the flow of air, gas or vapor to and from one or more locations. A fan provides the necessary energy
SYSTEM, CENTRAL FAN
A mechanical, indirect system of heating, ventilating, or air conditioning, in which the air is treated or handled by equipment located outside the rooms
SYSTEM, CLOSED
A heating or refrigerating piping system in which circulating water or brine is completely enclosed, under pressure above atmospheric, and shut off from the
SYSTEM, DUCT
A series of ducts, conduits, elbows, branch piping, etc. designed to guide the flow of air, gas or vapor to and from one or more locations. A fan provides the necessary
SYSTEM, FLOODED
A 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
SYSTEM, UNITARY
A complete, factory
assembled and factory
tested refrigerating system comprising one or more assemblies which may be shipped as one unit or separately but
SYSTEMS CURVE
A graphic presentation of the pressure vs. volume flow rate characteristics of a particular system.
TAlL PIPE
Outlet pipe from the evaporator.
TANNINS
A chemical used as an inhibitor in relation with caustic embrittlement.
TEMPERATURE
Degree of hotness or coldness as measured by a thermometer.
TEMPERATURE
Degree of hotness or coldness as measured by a thermometer.
TEMPERATURE CONTROL
Temperature
TEMPERATURE CRITICAL
The saturation temperature corresponding to the critical state of the substance at which the properties of the liquid and vapor are identical.
TEMPERATURE, DEWPOINT
The temperature at which the condensation of water vapor in a space begins for a given state of humidity and pressure as the temperature of the vapor is
TEMPERATURE, DRYBULB
The temperature of a gas or mixture of gases indicated by an accurate thermometer after correction for radiation.
TEMPERATURE, EFFECTIVE
An arbitrary index which combines into a single value the effect of temperature, humidity, and air movement on the sensation of warmth or cold felt by the
TEMPERATURE, SATURATION
The temperature at which no further moisture can be added to the air water vapor mixture. Equals dew point temperature.
TEMPERATURE, WET BULB
Thermodynamic wet bulb temperature is the temperature at which liquid or solid water, by evaporating into air, can bring the air to saturation adiabatically
TEMPERATURE
HUMIDITY INDEX
TENSILE STRENGTH
In tensile testing, the ratio of maximum load to original cross
TENSILE STRESS
A stress that causes two parts of an elastic body, on either side of a typical stress plane, to pull apart.
TENSION
The force or load that produces elongation.
TERMINAL VELOCITY
The maximum air stream velocity at the end of the throw.
THE FIRST LAW
(1 ) When work is expanded in generating heat, the quantity of heat produced is proportional to the work expended
performance of work, the quantity of heat which disappears is proportional to the work done (Joule)
(2) If a system is caused to change from an initial state to a final state by adiabatic
means only, the work done is the same for all adiabatic paths connecting the two states (Zemansky)
(3) In any power cycle or refrigeration cycle, the net heat absorbed by the working
Therm
Measurement used by gas utilities for billin3 purposes. 1 Therm = 100 cubic feet of gas = 100,000 Btu.
THERM
Quantity of heat equal to 100000 Btu.
THERMAL CONDUCTIVITY
The rate at which heat is transferred through an object.
THERMAL CONDUCTIVITY
The rate of heat flow, under steady conditions, through unit area, per unit temperature gradient in the direction perpendicular to the area. It is given in the
THERMAL EFFICIENCY
Ratio of shaft work out of a system to the heat energy into the system.
THERMAL EFFICIENCY OF A GAS TURBINE
Is the energy output of the gas turbine divided by the energy input of the gas turbine.
THERMAL ELECTROMOTIVE FORCE
The electromotive force generated in a circuit containing two dissimilar metals when one junction is at temperature different from that of the
THERMAL EQUILIBRIUM
When two bodies originally at different temperatures, have attained the same temperature
THERMAL EXPANSION
The change in length of a material with change in temperature.
THERMAL SHOCK
The development of a steep temperature gradient and accompanying high stress within a material or structure.
THERMAL TREATMENT
Refers to the treatment of water with heat to drive off the dissolved gases and soften certain minerals for easy removal.
THERMISTOR
A two
THERMOBANK
A bank for storing heat.
THERMOCOUPLE
Device for measuring temperature utilizing the fact that an electromotive force is generated whenever two junctions of two dissimilar metals in an electric circuit are
THERMOCOUPLE
Device which generates electricity, using the principle that if two unlike metals are welded together and junction is heated, voltage will develop across the open
THERMOCOUPLE
Device which generates electricity, using the principle that if two unlike metals are welded together and junction is heated, voltage will develop across the open
THERMOCOUPLE THERMOMETER
Electrical instrument using thermocouple as source of electrical flow, connected to millimeter calibrated in temperature degrees.
THERMODISK DEFROST CONTROL
Electrical switch with bimetal disk controlled by temperature changes.
THERMODYNAMIC PROPERTIES
Basic qualities used in defining the condition of a substance, such as temperature, pressure, volume, enthalpy, entropy.
THERMODYNAMICS
Part of science which deals with the relationships between heat and mechanical action.
THERMOELECTRIC REFRIGERATION
Where refrigeration is produced by the passage of electric current through two dissimilar materials.
THERMOELECTRICITY
In physics, electricity generated by the application of heat to the junction of two dissimilar materials. If two wires of different materials are joined at their ends
THERMOMETER
Device for measuring temperatures.
THERMOMODULE
Number of thermocouples used in parallel to achieve low temperatures.
THERMOPILE
Number of thermocouples used in series to create a higher voltage.
THERMOSTAT
Device, which senses ambient temperature, conditions and, in turn, acts to control a circuit.
THERMOSTATIC CONTROL
Device which operates system or part of system based on temperature change.
THERMOSTATIC VALVE
Valve controlled by temperature change response elements.
THERMOSTATIC WATER VALVE
Valve used to control flow of water through system, actuated (made to work) by temperature difference. Used in units such as water
THREE
WAY VALVE
Multi
orifice (opening) flow control valve with three fluid flow openings.
THRESHOLD TREATMENT
Chemical treatment, used to prevent scale formation, which acts to hold hardness in solution at the threshold of precipitation.
THROTTLING
An irreversible adiabatic steady flow process in which the fluid is caused to flow through an obstruction in a pipe with a resulting drop in pressure.
THROTTLING RANGE
The amount of change in the variable being controlled to make the controlled device more through the full length of its stroke.
TIMER
THERMOSTAT
TITRATION
A chemical process used in analyzing feedwater.
TON REFRIGERATION UNIT
Unit which removes same amount of heat in 24 hours as melting of 1 ton of ice.
TONNS OF REFRIGERATION
The capacity of a refrigeration system that can freeze 1 tonne (1000 kg) of liquid water at 0°C into ice at 0°C in 24 hour is said to be 1 tone.
TOOL STEEL
Any steel used o make tools for cutting, forming, or otherwise shaping a material into a final part.
TOTAL DYNAMIC HEAD
Dynamic discharge head (static discharge head, plus friction head, plus velocity head) plus dynamic suction lift, or dynamic discharge head minus dynamic
TOTAL HARDNESS
See Hardness.
TOTAL HEAT
Sum of both the sensible and latent heat.
TOTAL HEAT (ENTHALPY)
Total heat is the sum of the sensible heat and latent heat in an exchange process. In many cases, the addition or subtraction of latent and sensible heat at
TOTAL SOLIDS
Are the sum of the dissolved and suspended solids.
TOWER FILL
The interior structure of a cooling tower over which the water flows.
TRACE CONSTITUENTS
Materials present at a concentration less than 0.01 mg/L.
TRANCSMITTANCE, THERMA (U FACTOR)
The time rate of heat flow per unit area under steady conditions from the fluid on the warm side of a barrier to the fluid on the cold side,
TRANSDUCER
The means by which the controller converts the signal from the sensing device into the means necessary to have the appropriate effect on the controlled device. For
TRANSFORMER
The system power supplying transformer is an inductive stationary device which transfers electrical energy from one circuit to another. The transformer has two
energy at the same voltage
a step
down transformer transfers energy at a lower voltage, and a step
up transformer transfers energy at a higher voltage.
TRANSIENT CONSTITUENTS
Are those constituents which change in concentration or activity by changes in the aquatic environment. The change my be due to oxidation
TRANSISTOR
An active semiconductor device capable of providing power amplification and having three or more terminals.
TREATMENT
A process whereby impurities are removed from water
TRIBOLOGY
The science concerned with the design, friction, lubrication and wear of contacting surfaces that move relative to each other (as in bearings, cams, or gears).
TUBE SHEET
The portion of a heat exchanger or boiler in to which the tubes are rolled or secured.
TUBERCLE
A protective crust of corrosion products (rust) which builds up over a pit caused by the loss of metal due to corrosion.
TUBERCULATION
A corrosion process that produces hard knob
TUBE
WITHIN
A
TUBE
Water
cooled condensing unit in which a small tube is placed inside large unit. Refrigerant passes through outer tube, water through the inner tube.
TURBIDITY
The measure of suspended matter in, a water sample which contributes to the reflection of light or cloudiness.
TURBIDITY UNIT
The unit of measure of suspended matter in water. It is the measure of light compared against light reflected by a reference standard as defined by the standard
TURBINE METER
A device used to measure water consumption in industrial plants.
TURBULATOR
Spiral wound or spiral shaped piece located in the liquid tube of a heat exchanger.
TURNER GAUGE
A device used to measure the actual scale
TWO
TEMPERATURE VALVE
Pressure
opened valve used in suction line on multiple refrigerator installations, which maintains evaporators in a system at different temperatures.
TWO
WAY VALVE
ULTIMATE STRENGTH
The maximum stress (tensile, compressive or shear) a material can sustain without fracture. It is determined by dividing maximum load by the original
cross
sectional area of the specimen.
ULTRA FILTRATION
A process that forces water through a filtering membrane by means of pressure gradients in order to obtain ultra pure water.
UNDERDEPOSIT ATTACK
Corrosion under or around a localized deposit on a metal surface (a form of crevice corrosion).
UNITARY SYSTEM
A room unit which performs part or all of the air conditioning functions. It may or may not be used with a central fan system.
UNLOADER
A device in or on the compressor for equalizing high
side and low
side pressures for a brief time during starting and for controlling compressor capacity by rendering one
UPFLOW
The operation of an ion
UPFLOW FILTER
A unit containing a single filter medium, usually with graded sand.
UPFLOW FURNACE
A furnace in which the heated air flows upward as it leaves the furnace.
UPSTREAM
The inlet side of an instrument, a pump, valve, etc..
UTILITY TRANSFORMER
Primary and secondary coils of wire which reduce (step down) the utility supply volt age for use within a facility.
U
TUBE MANOMETER
A U
shaped section of plastic or glass tubing that is partially filled with water or mercury. They are used to measure the lower pressure ranges of gases.
VACUUM
Pressure lower than atmospheric pressure.
VACUUM BREAKER
A device to prevent a suction in a water pipe.
VACUUM PUMP
Special high efficiency device used for creating high vacuums for testing or drying purposes.
VALVE, MODULATING
A valve which can be positioned anywhere between fully on and fully off to proportion the rate of flow in response to a modulating controller (see modulating
VALVE, NEEDLE
A form of globe valve that contains a sharp pointed, needle like plug that is driven into the and out of a cone shaped seat to accurately control a relatively small rate
VALVE, POP
A spring loaded safety valve that opens automatically when pressure exceeds the limits for which the valve is set. It is used a safety device on pressurized vessels and
VALVE, POPPET
A device that controls the rate of flow of fluid in a line or opens or shuts of the flow of fluid completely. When open, the sealing surface of the valve is moved away
VALVE, PRESSURE RELIEF
A valve designed to minimize the possibility of explosion when air temperature surrounding a refrigeration system may rise to a point where the pressure
VALVE, RELIEF
Also called pressure relief valve.
VALVE, TWO
POSITION
A valve which is either fully on or fully off with no positions between. Also called an “on
off valve”.
VAPOR
A gas, particularly one near to equilibrium with the liquid phase of the substance and which does not follow the gas laws. Usually used instead of gas for a refrigerant, and, in
VAPOR BARRIER
A moisture
VAPOR LOCK
A condition where liquid flow is impeded by vapor trapped in a liquid line.
VAPOR PHASE INHIBITORS
A system using an organic nitrite compound, a powder which vaporizes slowly to protect ferrous metal from contact with oxygen.
VAPOR PRESSURE
Vapor pressure denotes the lowest absolute pressure that a given liquid at a given temperature will remain liquid before evaporating into its gaseous form or state.
VAPOR, SATURATED
Vapor in equilibrium with its liquid
VAPOR, SUPERHEATED
Vapor at a temperature which is higher than the saturation temperature (i.e., boiling point) at the existing pressure.
VAPOR, WATER
Water used commonly in air conditioning parlance to refer to steam in the atmosphere.
VAPOROUS CARRYOVER
Referring to impurities carried over with the steam and then forming a deposit on turbine bladings. This type of carryover is difficult to prevent.
VELOCITY
A vector quantity which denotes, at once, the time rate and the direction of a linear motion.
VELOCITY HEAD
The pressure needed to accelerate the fluid being pumped.
VELOCITY, TERMINAL
The highest sustained air stream velocity existing in the mixed air path at the end of the throw.
VENA CONTRACTA
The place along the axis of flow, just below the orifice, when the jet stream contracts to its minimum.
VENT
An opening in a vessel or other enclosed space for the removal of gas or vapor.
VENTILATION
The process of supplying or removing air by natural or mechanical means, to or from a space
VENTURI TUBE METER
A flow meter used to determine the rate of flow and employing a venturi tube as the primary element for creating differential pressure in flowing gases or
VISCOSITY
That property of semi
VISCOSITY INDEX
A commonly used measure of the change in viscosity of a fluid with temperature. The higher the viscosity index, the smaller the relative change in viscosity with
VITAL HEAT
The heat generated by fruits and vegetables in storage
VOLATILE SOLIDS
Those solids in water or other liquids that are lost on ignition of dry solids at 550°F.
VOLATILE TREATMENT
Based on the use of hydrazine and neutralizing amines or ammonia. Leaves no solids in the boiler.
VOLATILITY
Volatility, surface tension and capillary action of a fluid are incidental to environmental systems. Volatility is the rapidity with which liquids evaporates extremely rapidly
VOLT
The unit of potential difference or electromotive force in the meter
kilogram
second system, equal to the potential difference between two points for which 1 coulomb of
VOLTAGE (E)
The electromotive force in an electrical circuit. The difference in potential between two unlike charges in an electrical circuit is its voltage measured in “volts” (V).
VOLTAGE DROP
The voltage drop around a circuit including wiring and loads must equal the supply volt age.
VOLTAIC CELL
A storage device that converts chemical to electrical energy.
VOLUME, SPECIFIC
The volume of a substance per unit mass
WALK
IN
COOLER
A large commercial refrigerated space often found in supermarkets or places for whole sale distribution.
WASTE WATER
The used water and solids from industrial processes that flow to a treatment plant.
WATER
A tasteless, odorless, colorless liquid in its pure state.
WATER ABSORPTION
The amount of weight gain (%) experienced in a polymer after immersion in water for a specific length of time under controlled environment.
WATER HAMMER
Banging of pipes caused by the shock of closing valves (faucets). //////////////////
WATER LUBRICANT
Water used as a lubricant
WATER SOFTENER
A device or system used to remove calcium and magnesium hardness minerals from a water supply.
WATER TUBE
A boiler tube through which the fluid under pressure flows. The products of combustion surround the tube.
WATER VAPOR
In air conditioning, the water in the atmosphere.
WATER, BRAKISH
(1) Water having less salt than sea water, but undrinkable. (2) Water having salinity values ranging from about 0.5 to 17 parts per thousand.
WATER, POTABLE
Water that is safe to drink.
WATER, SOUR
Waste waters containing fetid materials, usually sulfur compounds.
WATER
ICE REFRIGERATION SYSTEM
WATERLEG
That space that is full of boiler water between two parallel plates. It usually forms one or more sides of internally fired boilers.
WATERWALL
A row of water tubes lining a furnace or combustion chamber, exposed to the radiant heat of the fire.
WATT (W)
A measure of electric power equal to a current flow of one ampere under one volt of pressure
WEIGHT TO POWER RATIO
It is the weight of the machine producing work. For example
WET BULB
Device used in measurement of relative humidity. Evaporation of moisture lowers temperature of wet bulb compared to dry bulb temperature in same area.
WET BULB TEMPERATURE (WB)
The temperature registered by a thermometer whose bulb is covered by a saturated wick and exposed to a current of rapidly moving air. The wet
WET STANDBY
Boiler is filled completely with water or maintained at normal operating level with a positive nitrogen pressure of 35 to 70 kPa.
WET
BULB DEPRESSION
The difference between the dry
bulb temperature and the wet bulb temperature.
WINDAGE DRIFT
That water lost from an open re
circulating
water system by means of wind blown through the spray area that carries water out of the system. This is not the same as
WOBBLE PLATE
SWASH PLATE
WORKING FLUID
is the substance which does the work in a heat engine. The air is one of the working fluids used with gas turbines. Freons are the working fluids used with some
ZEOLITE
A natural mineral (hydrous silicates) that has the capacity to absorb hardness, calcium, and magnesium ions from water.
ZEOLITE SOFTENING
Refers to the process, where zeolite chemicals are capable to exchange ions with the hardness causing impurities of the water.
ZETA POTENTIAL
The difference in voltage between the surface of the diffuse layer surrounding a colloidal particle and the bulk liquid beyond.
ZONING
The practice of dividing a building into small sections for heating and cooling control. Each section is selected so that one thermostat can be used to determine its
SUCTION LIFT
A pumping condition where the eye of the impeller of the pump is above the surface of the water from which the pump is pumping.
SUCTION LIFT
A pump condition where the eye of the impeller of the pump is below the surface of the water from which the pump is pumping.
VANE
That portion of an impeller which throws the water toward the volute case.
VELOCITY HEAD
The vertical distance a liquid must fall to acquire the velocity with which it flows through the piping system. For a given quantity of flow, the velocity head will vary
VOLUTE
The spiral
