Amount of moisture in the air, indicated in grains per cubic foot

Gauge pressure plus atmospheric pressure

Temperature measured from absolute zero

Temperature at which all molecular motion ceases (460F and 273C and 0K)

Substance which has the ability to take up or absorb another substance

Refrigerator which creates low temperatures by using the cooling effect formed when a refrigerant is absorbed by chemical substances

Storage tank which receives liquid refrigerant from evaporator and prevents it from flowing into suction line

Mechanism designed to lower temperature of air passing through it

Thermostat unit in which sensing element is located in refrigerated space

Heat of compression is transferred from condensing coils to surrounding air. This may be done either by convection or by a fan or blower

Screw with recessed head designed to be turned with hex shaped wrench

Electric current in which direction of flow alternates or changes. In 60 cycle current direction of flow reverses every 120th second. In the UK this is 50 cycles/second (also known as Hertz abbreviated to Hz)

Temperature of fluid (usually air) which surrounds object on all sides

An electric meter used to measure current, calibrated in amperes

Chemical combination of nitrogen and hydrogen (NH3 ). Ammonia refrigerant is identified by R-717

Instrument for measuring the rate of flow of air

Process of heat treating metal to obtain desired properties of softness and ductility (easy to form into new shape)

Pressure that gases in air exert upon the earth, measured in pounds per square inch or bar (14.5 psig or 1 bar)

System of removing ice and frost from evaporators automatically (usually by time)

Example of azeotropic mixture-refrigerant R502 is mixture consisting of 48.8% refrigerant R-22, and 51.2% R-115. The refrigerants do not combine chemically, yet azeotropic mixture provides refrigerant characteristics desired ie constant proportions and no change in evaporating /condensing temperature, for a given pressure