WD Catalog 2018

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Glossary
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recycle — the process of removing contaminants
(moisture, acid, particulate matter) from a refriger-
ant
reed valve — suction and discharge valves located
in the valve plate of the compressor
refrigerant — a substance used in HVAC systems
to control heat energy
refrigerant cycle — one complete revolution of
refrigerant through the system which includes
changes of state of the refrigerant from liquid to
vapor or gas and back to liquid
refrigeration oil — a specially manufactured oil
free from moisture and all contaminants
relative humidity — the amount of moisture in
the air as compared to the total amount the air can
hold at a given temperature and altitude
resistor — a voltage dropping device, usually wire
wound, which provides a means of controlling fan
or blower speed
retrofitting — reconditioning an R-12 AC system
to use R-134a
rotary vane compressor — a type of compressor
which uses internal vanes rather than pistons to
operate and pump the refrigerant through the sys-
tem
rotating coil clutch — an old type clutch where
the magnetic coil is part of the clutch pulley — now
replaced universally by the stationary coil design
where the coil is bolted to the compressor body
Schrader valve — a spring loaded valve inside
some service fittings, similar to a tire valve; also
found on some accumulators
serpentine — a condenser coil formed from one
piece of extruded aluminum tubing
service port — a fitting on control devices and
service valves allowing connection of manifold
gauge hoses
service valve — see “low side service valve” and
“high side service valve”
shaft seal — see “compressor shaft seal”
sight glass — a window usually in the top of the
receiver-drier for observing the condition of the
refrigerant
silica gel — a type of desiccant which removes
moisture from refrigerant
solenoid valve — an electromagnetic valve con-
trolled by electrical current energizing and de-en-
ergizing a coil to open or close the valve
specific heat — the amount of heat required to
change the temperature of one pound of a sub-
stance 1 degree Fahrenheit
stationery coil clutch — the magnetic clutch
used to drive the compressor
stem-type valve — a service valve with a
threaded valve stem for three position adjustment,
back-seated, mid position and front-seated
suction line — the line connecting the evaporator
outlet to the compressor inlet; the low pressure
lines
suction service valve — see “low side service
valve”
suction side — the low pressure portion of the
system, from expansion valve orifice to compressor
inlet
sump — the portion of a compressor where oil is
contained, waiting to be circulated
superheat — heat added to a gas after evapora-
tion from a liquid state (the approximate tempera-
ture rise across the evaporator coil)
SUVA — Dupont trademark for R-134a
superheat switch — a switch mounted on the
compressor and connected to a thermal limiter and
fuse, used in some GM systems to sense low refrig-
erant and protect the compressor
temperature range — a measured spread be-
tween a high and low temperature
thermal limiter — a protective device with a fuse
and used with a superheat switch to stop the com-
pressor when low pressure is sensed by the super-
heat switch