All Terms 2 Flashcards
CONDENSATE
The liquid formed by condensation of a vapor. In steam heating, water condensed from steam
CONDENSATE POLISHER
A device used to clean the returning condensate to the boiler feedwater system.
CONDENSATE PUMP
Device to remove water condensate that collects beneath an evaporator.
CONDENSATION
Process of changing a vapor into liquid by extracting heat. Condensation of steam or water vapor is effected in either steam condensers or dehumidifying coils, and
CONDENSE
Action of changing a gas or vapor to a liquid.
CONDENSER
An apparatus used to transfer heat from a hot gas, simultaneously reducing that gas to a liquid.
CONDENSER TUBE
The heat transfer surface in a condenser.
CONDENSER
WATER SYSTEM
A re
circulating cooling water used as a heat transfer fluid for the condensation of a gas.
CONDENSING TEMPERATURE
The temperature at which the condensing gas is returned to a liquid at the same pressure.
CONDENSING UNIT
Part of a refrigerating mechanism which pumps vaporized refrigerant from the evaporator, compresses it, liquefies it in the condenser and returns it to the
CONDENSING UNIT SERVICE VALVES
Shutoff valves mounted on condensing unit to enable service technicians to install and/or service unit.
CONDENSING UNIT, REFRIGERANT
An assembly of refrigerating components designed to compress and liquefy a specific refrigerant, consisting of one or more refrigerant
CONDUCTANCE, ELECTRICAL
The reciprocal (opposite) of resistance and is the current carrying ability of any wire or electrical component. Resistance is the ability to oppose the
CONDUCTANCE, SURFACE FILM
Time rate of heat flow per unit area under steady conditions between a surface and a fluid for unit temperature difference between the surface and
CONDUCTION
Transfer of heat by direct contact.
CONDUCTIVITY (ELECTRICAL)
The ability of a liquid to conduct an electrical current and indicating the presence of cations and anions. Conductivity is usually expressed in
CONDUCTIVITY (THERMAL)
The time rate of heat flow through unit thickness of an infinite slab of homogeneous material in a direction perpendicular to the surface, induced by unit
CONDUCTIVITY METER
An electric instrument used to measure the conductivity of water to determine its content of dissolved solids.
CONDUCTIVITY, THERMAL
The time rate of heat flow through unit area and unit thickness of a homogeneous material under steady conditions when a unit temperature gradient is
CONDUCTOR
Substance or body capable of transmitting electricity or heat.
CONDUIT
A round cross
CONGEALER
Also known as freezer.
CONGRUENT PHOSPHATE CONTROL
Similar as a coordinated phosphate control but more restrictive where the equilibrium is based on maintaining a ratio of 2.6 Na/1.0 PO4, instead
CONNECTED LOAD
The sum of all loads on a circuit. (1) Connection in Parallel: System whereby flow is divided among two or more channels from a common starting point or header.
CONSTRICTOR
Tube or orifice used to restrict flow of a gas or a liquid.
CONTAMINATION
The introduction into water of microorganisms, chemicals, toxic materials, waste water in a concentration that makes the water unfit for its next intended use.
CONTROL
A 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,
CONTROL POINT
The value of the controlled variable which the controller operates to maintain.
CONTROL VALVE
Valve which regulates the flow or pressure of a medium which affects a controlled process. Control valves are operated by remote signals from independent devices
CONTROLLED DEVICE
One which receives the converted signal from the transmission system and translates it into the appropriate action in the environmental system. For example: a
CONTROLLER
A device capable of measuring and regulating by receiving a signal from a sensing device, comparing this data with a desired value and issuing signals for corrective
CONVECTION
The movement of a mass of fluid (liquid or gas) caused by differences in density in different parts of the fluid
CONVECTION, FORCED
Convection resulting from forced circulation of a fluid, as by a fan, jet or pump.
CONVECTION, NATURAL
Circulation of gas or liquid (usually air or water) due to differences in density resulting from temperature changes.
CONVERGENT
DIVERGENT NOZZLE
COOLER
Heat exchanger which removes heat from a substance.
COOLING EFFECT, SENSIBLE
The difference between the total cooling effect and the dehumidifying effect, usually in watts.
COOLING EFFECT, TOTAL
Difference between the total enthalpy of the dry air and water vapor mixture entering the cooler per hour and the total enthalpy of the dry air and water
COOLING TOWER
Device for lowering the temperature of water by evaporative cooling, in which water is showered through a space through which outside air circulates. A portion of
COOLING, EVAPORATIVE
Involves the adiabatic exchange of heat between air and water spray or wetted surface. The water assumes the wet
COOLING, REGENERATIVE
Process of utilizing heat which must be rejected or absorbed in one part of the cycle to function usefully in another part of the cycle by heat transfer.
CORRATOR
A device or probe employed to measure current flow in a process flow. It consists of two identical electrodes, to which a small current is applied and measured, from which
CORROSION
The chemical or electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the material and its properties.
CORROSION, ANODE
The dissolution of an metal acting as an anode.
CORROSION, ATMOSPHERIC
The gradual degradation or alteration of a material by contact with substances present in the atmosphere, such as oxygen, carbon dioxide, water vapor,
CORROSION, BIOLOGICAL
Deterioration of metals as a result of the metabolic action of microorganisms. Also often named fouling.
CORROSION, CATHODIC
Corrosion resulting resulting from a cathodic condition of a structure usually caused by the reaction of an amphoteric metal with the alkaline products of
CORROSION, CAVITATION
A process involving conjoint corrosion and cavitation.
CORROSION, CONCENTRATION ATTACK
A form of corrosion caused by the concentration of caustic or phosphate salts under porous deposits, generally iron oxide. Sometimes
CORROSION, CONCENTRATION
CELL
CORROSION, COUPONS
Pre
CORROSION, CREVICE
Localized corrosion of a metal surface at, or immediately adjacent to an area that is shielded from full exposure to the environment because of close proximity
CORROSION, DEACTIVASION
The process of prior removal of the active corrosive constituents, usually oxygen, from a corrosive liquid by controlled corrosion of expendable metal
CORROSION, DEPOSIT (also called poultice corrosion)
Corrosion occuring under or around a discontinous deposit on a metallic surface.
CORROSION, EFFECT
A change in any part of the corrosion system caused by corrosion.
CORROSION, ELECTROCHEMICAL
Corrosion that is accompanied by a low of electrons between cathodic and anodic areas on metallic surfaces.
CORROSION, EMBRITTLEMENT
The severe loss of ductility of a metal resulting from corrosive attack, usually intergranular and often not visible.
CORROSION, EXTERNAL
A chemical deterioration of the metal on the fireside of boiler heating surfaces.
CORROSION, FATIGUE
The process in which a metal fractures prematurely under conditions of simultaneous corrosion and repeated cyclic loading at lower stress levels or fewer
CORROSION, FILIFORM
Corrosion that occurs under organic coatings on metals as fine wavy hairlines.
CORROSION, FRETTING
A type of corrosion which occurs where metals slide over each other. Long tubes in heat exchangers often vibrate, causing metal to metal contact, tube
CORROSION, GALVANIC
Corrosion of a metal caused by its contact with a metal of lower activity
CORROSION, GASEOUS
Corrosion with gas as the only corrosive agent and without any aqueous phase on the surface of the metal. Also called dry corrosion.
CORROSION, GENERAL
A form of deterioration that is distributed more or less uniformly over a surface.
CORROSION, GRAPHITIC
Corrosion of grey iron in which the iron matrix is selectively leached away, leaving a porous mass of graphite behind. This type of corrosion occurs in
CORROSION, HOT
An accelerated corrosion of metal surfaces that results from the combined effect of oxidation and ractions with sulfur compounds or other contminants such as
CORROSION, IMPINGEMENT
A form of erosion
CORROSION, INFLUENCED
The corrosion cause by organisms due to their discharge containing sulfur compounds and the depolarization with other types of discharge due to the
CORROSION, INHIBITORS
Substances that slow the rate of corrosion.
CORROSION, INTERCRYSTALINE
(see intergranular cracking)
CORROSION, INTERGRANULAR
Localized attack occurring on the metal grain boundaries. This is commonly found with stainless steels which have been improperly heat treated.
CORROSION, INTERNAL
Usually refers to the internal corrosion and is considered an electrochemical deterioration of the boiler surface at or below the water surface.
CORROSION, LOCALIZED
Corrosion at discrete sites, for example, crevice corrosion, pitting, and stress
CORROSION, LOCALIZED
Non
uniform corrosion of a metal surface highlighted by spotty or pitting
type corrosion.
CORROSION, MICROBIAL
(see biological corrosion).
CORROSION, OXYGEN DEFICIENCY
A form of crevice corrosion in which galvanic corrosion proceeds because oxygen is prevented from diffusing into the crevice.
CORROSION, POTENTIAL
The voltage between a corroding metal and a reference electrode.
CORROSION, POULTICE
(see corrosion, deposit)
CORROSION, POULTICE
A term used in the automotive industry to describe the corrosion of vehicle body parts due to the collection of road salts and debries on ledges and in
CORROSION, PROTECTION
Modification of a corrosion system so that corrosion damage is mitigated.
CORROSION, RESISTANCE
The ability of a material to resist deterioration by chemical or electrochemical reaction with its environment.
CORROSION, STRAY CURRENT
A form of attack caused by electrical currents going through unintentional path.
CORROSION, STRESS
Preferential attack of areas under stress in a corrosive environment, where such a environment alone would not have caused corrosion.
CORROSION, STRESS CORROSION CRACKING
Material deterioration due to cracking, by being under static stress either applied or residual.
CORROSION, SWEET
The deterioration of metal caused by contact with carbon dioxide in water.
CORROSION, THERMO
GALVANIC
CORROSION, UNIFORM
The simplest form of corrosion. It attacks all surfaces exposed to a corrodent.
CORROSIVE WEAR
A material deterioration due to the co
CORROSIVITY
An indication of the corrosiveness of the water of material. The corrosivity of a water as described by the water’s pH, alkalinity, hardness, temperature, total dissolved
COUNTER
FLOW HEAT EXCHANGER
COVALENT BOND
A bond in which two atoms share pair of electrons.
CRANKSHAFT SEAL
Leak proof joint between crankshaft and compressor body.
CRAZE CRACKING (OR CHECKING)
Irregular surface cracking of metal associated with thermal cycling.
CREEP
Time dependent permanent strain under stress. This is used to rate the resistance of a material to plastic deformation under sustained load.
CREEP STRENGTH
The constant nominal stress that will cause a specified quantity of creep in a given time at constant temperature. Creep strength is expressed as the stress
CREEP, DYNAMIC
Creep that occurs under conditions of fluctuating load or fluctuating temperatures.
CRISPER
Drawer or compartment in refrigerator designed to provide high humidity along with low temperature to keep vegetables, especially leafy vegetables
CRITICAL HUMIDITY
The relative humidity above which the atmospheric corrosion rate of some metals increase sharply.
CRITICAL POINT
A point at which the saturated liquid and saturated vapor states are identical. Also, the latent heat of evaporization is zero at this point.
CRITICAL PRESSURE
The pressure at the critical temperature above which the fluid no longer has the properties of a liquid, regardless of further increase of pressure.
CRITICAL TEMPERATURE
That temperature above which the vapor phase cannot be condensed to liquid by an increase in pressure.
CRITICAL VELOCITY
The velocity above which fluid flow is turbulent.
CRT
Cathode ray tube terminal.
CRYOGENIC FLUID
Substance which exists as a liquid or gas at ultra
low temperatures
157°C.
CRYOGENIC SUPERCONDUCTOR SYSTEM
Uses helium to cool conductors to within few degrees of absolute zero where they offer no electric resistance.
CRYOGENICS
Refrigeration which deals with producing temperatures of
CRYSTALLITES
Atoms arranged in a repeating and definite structure.
CRYSTALLIZATION
The separation, usually from a liquid phase on cooling, of a solid crystalline phase.
CURRENT (I)
The electric flow in an electric circuit, which is expressed in amperes (amps).
CURRENT DENSITY
The current flowing to or from a unit area of an electrode surface.
CYCLE
A series of thermodynamic processes during which the working fluid can be made to undergo changes involving energy transition and is subsequently returned to its original
CYCLE, REVERSIBLE
Theoretical thermodynamic cycle, composed of a series of reversible processes, which can be completely reversed.
CYCLE, WATER TREATMENT
A complete course of ion
CYCLES
A system that undergoes a series of processes and always returns to its initial state.
CYCLES OF CONCENTRATION
The number of times the soluble mineral salts in a water supply have been concentrated in, a system.
CYLINDER HEAD
Plate or cap which encloses compression end of compressor cylinder.
DALTON’S LAW OF PARTIAL PRESSURE
Each constituent of a mixture of gases behaves thermodynamically as if it alone occupied the space. The sum of the individual pressures
DAMPER
A device used to vary the volume of air passing through an air outlet, air inlet or duct.
DASHPOT
A damping device, usually consisting of a cylinder and a piston in which relative motion of either displaces a fluid such as air or oil, resulting in friction.
DEADBAND
In HVAC, a temperature range in which neither heating nor cooling is turned on
DE
AERATING HEATERS
DE
AERATION
DE
AERATOR
DE
ALKALIZATION
DE
ALKALIZER
DE
ALLOYING
DEASHING
The removal from a solution of inorganic salts by means of adsorption by ion
DE
CARBONATION
DECIBEL (dB)
A decibel is a division of a logarithmic scale for expressing the ratio of two quantities proportional to power or energy. The number of decibels denoting such a ratio is
DECONCENTRATOR
This is a cylindrical tank connected before the boiler to receive the boiler feedwater before entering the boiler. It is designed to promote settling of suspended
DE
FLOCCULANT
DEFROST CYCLE
Refrigerating cycle in which evaporator frost and ice accumulation is melted.
DEFROST TIMER
Device connected into electrical circuit which shuts unit off long enough to permit ice and frost accumulation on evaporator to melt.
DEFROSTING
Process of removing frost accumulation from evaporators.
DEFROSTING CONTROL
Device to automatically defrost evaporator. It may operate by means of a clock, door cycling mechanism or during “off” portion of refrigerating cycle.
DEFROSTING TYPE EVAPORATOR
Evaporator operating at such temperatures that ice and frost on surface melts during off part of operating cycle.
DEGREE DAY
A unit, based upon temperature difference and time, used in estimating fuel consumption and specifying nominal heating load of a building in winter. For any one day,
DEGREES OF SUPERHEAT
The amount by which the temperature of a superheated vapor exceeds the temperature of the saturated vapor at the same pressure.
DEHUMIDIFICATION
The condensation of water vapor from air by cooling below the dewpoint or removal of water vapor from air by chemical or physical methods.
DEHUMIDIFIER
(1) An air cooler or washer used for lowering the moisture content of the air passing through it
DEHUMIDIFYING
Removal of moisture from the air.
DEHYDRATION
The removal of water vapor from air, stored goods or refrigerants.
Deionization
Deionization, a more general term than deashing, embraces the removal of all charged constituents or ionizable salts (both inorganic and organic) from solution.
DE
IONIZER
DEMAND
The probable maximum rate of water flow as determined by the number of water supply fixture units.
DEMAND CHARGE
That part of an electric bill based on kW demand and the demand interval, expressed in dollars per kilowatt. Demand charges offset construction and maintenance
DEMAND CONTROL
A device which controls the kW demand level by shedding loads when the kW demand exceeds a predetermined set point.
DEMAND INTERVAL
The period of time during which kW demand is monitored by a utility service, usually 15 or 30 minutes long.
DEMAND LOAD
The actual amount of load on a circuit at any time. The sum of all the loads which are ON. Equal to the connected load minus the loads that are OFF.
DEMAND READING
Highest or maximum demand for electricity an individual customer registers in a given interval, example, 15 minute interval. The metered demand reading sets the
DEMINERALIZER
A process to remove dissolved matter from boiler pretreated water by contacting the water with ion
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
DENSITY, ABSOLUTE
Mass per unit volume of a solid material, expressed usually in kg/m3.
DESALINATION
The removal of inorganic dissolved solids from water.
DESICANT, LIQUID
A hygroscopic liquid, such as glycol, used to remove water from other fluids.
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
DESIGN PRESSURE
Highest or most severe pressure expected during operation. Sometimes used as the calculated operating pressure plus an allowance for safety.
DESIGN PRESSURE
Highest or most severe pressure expected during operation. Sometimes used as the calculated operating pressure plus an allowance for safety.
DESIGN WORKING PRESSURE
The maximum allowable working pressure for which a specific part of a system is designed.
DESILICIZER
An apparatus or device used to remove silica from a water supply.
DESSERT BAG
A canvas bag which permits seepage of its liquid. The liquid will evaporate and obtains the to evaporate partly from the content of the bag and thus cooling its content.
DESSERT BAG
A canvas bag which permits seepage of its liquid. The liquid will evaporate and obtains the to evaporate partly from the content of the bag and thus cooling its content.
DETERGENT ADDITIVE
In lubrication technology, a surface active additive that helps to keep solid particles suspended in an oil
DETERGENT CLEANING
A boiler cleaning process using an alkaline solution, primarily to remove oil and grease.
DETERGENT OIL
A heavy duty oil containing a detergent additive. These oils are mainly used in combustion engines.
DETERGENT
DISPERSANT
A compound mixture of cleaning agents that have both surface
active properties and suspending properties.
DEW POINT
Temperature at which vapor (at 100 percent humidity) begins to condense and deposit as liquid.
DEW POINT DEPRESSION
The difference between dry bulb and dew point temperatures.
DEW POINT TEMPERATURE
The temperature at which condensation begins, if air is cooled at constant pressure.
DIAPHRAGM
Flexible material usually made of thin metal, rubber or plastic.
DIATOMACEOUS EARTH FILTRATION
Is a process in which a filter cake or precoat of diatomaceous earth is used as a filter medium.
DIELECTRIC
A nonconductor of electricity.
DIELECTRIC FITTING
A non conductive substance such as plastic that is placed between two dissimilar metals to prevent galvanic current flow.
DIELECTRIC STRENGTH
A measure of the ability of a dielectric (insulator) to withstand a potential difference across it without electric discharge.
DIFFERENTIAL
The temperature or pressure difference between cut
in and cut
out temperature or pressure of a control.
DIFFERENTIAL AERATION CELL
An electrolytic cell, the electomagnetic force of which is due to a difference in air (oxygen) concentration at one electrode as compared with that at
DIFFERENTIAL SOLUTE CONCENTRATION
A potential difference between an anode and cathode on metal, because of a concentration cell due to dissolved metals.
