WD Catalog 2018

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Glossary
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low side — the low pressure side of a system, from
the expansion valve orifice to the compressor inlet
low side service valve — a valve on the compres-
sor used to service the low pressure side of the
system and permit it to be checked
lubricant — refrigeration oil specially formulated
to be free of all contaminants and moisture. Note:
different for R-12 and R-134a
magnetic clutch — an electrically operated de-
vice used to cycle the compressor on and off
manifold — the part of the manifold gauge device
designed to control refrigerant flow
manifold gauge hoses — hoses connected to the
manifold gauge set used to test, evacuate, recover
and charge the air conditioning system
manifold gauge set — a system measuring device
containing two (sometimes three) gauges and three
or more service connections
melting point — the temperature at which a solid
turns into a liquid
mercury — used to indicate the amount of vacuum
(a perfect vacuum is 29.92 inches of mercury at sea
level)
molecular sieve — a drying agent used in the
receiver-drier to absorb moisture and filter con-
taminants out of the refrigerant
natures laws — the principals of conduct in natu-
ral process or function in nature
PAG — a polyalkylene glycol lubricant used in
many R-134a systems
parallel flow — a coil design where refrigerant
flows through both upper and lower tubing at the
same time
phosgene — a poison gas produced when R-12
comes in contact with an open flame
POA valve — a suction throttling valve used in
some systems
pressure drop — pressure lost while passing
through a component, the difference between pres-
sure in and pressure out
pressure range — a measured spread between a
high and low pressure
pressure switch — a pressure sensitive electrical
switch mounted at the receiver-drier, on some accu-
mulators or in the suction line to activate or inter-
rupt electrical current cycling the compressor
clutch
propane — a flammable gas used in the Halide
leak detector
psi — abbreviation for “pounds per square inch”
psig — abbreviation for “pounds per square inch
gauge”
purge — to remove the refrigerant from an AC
system and hoses by opening the system or using
pressure to eliminate the contents
R-12 — the common name of the refrigerant used
in vehicle air conditioner systems to move heat
energy
R-134a — a new refrigerant which does not harm
the atmosphere
radial compressor — a compressor that has pis-
tons in a radial design
radiation — heat waves (heat energy) passing
through the air
radiator shutter — a metal vane assembly on
some truck radiators where the vanes can be
opened or closed to allow or exclude ram air flow to
the radiator, radiator mounted condenser and en-
gine
ram air — air through which a vehicle passes,
increasing in force as the speed of the vehicle in-
creases
receiver-drier — a container which receives,
stores, and removes moisture from refrigerant
reciprocating compressor — a compressor hav-
ing pistons that move back and forth in cylinders
reclaim – the process of restoring refrigerant to
new product specifications
recovery – the process of removing refrigerant
from an AC system