TriPac Glossary
61
high pressure relief valve: A safety valve on the
refrigeration system that allows refrigerant to escape from the
system if pressure exceeds a predetermined value.
hp (horsepower): A unit of power equivalent to 746 watts
or 550 foot-pounds per second.
HPCO (High Pressure Cut Out Switch): A
pressure-operated switch that opens to stop unit operation
when discharge pressure reaches a predetermined maximum.
kPa: Kilopascals
. A metric unit of pressure. 1 kPa = 0.01 bar =
0.145 psi.
LPCO (Low Pressure Cut Out Switch): A
pressure-operated switch that opens to stop unit operation
when suction pressure reaches a predetermined minimum.
no. 1 diesel fuel: A grade of diesel fuel formulated to
prevent “jelling” in low ambient temperatures.
no. 2 diesel fuel: A grade of diesel fuel formulated for
moderate to warm ambient temperatures.
ohm: An electrical unit measuring the amount of resistance
(opposition to the current flow) in an electrical circuit.
pre-heat: The heating of diesel engine glow plugs prior to
start-up. Some engines use an intake manifold heater rather
than glow plugs.
pre-trip inspection: Checking the operation of a
refrigeration system before loading.
psi: Pounds per square inch. A unit of pressure.
1 psi = 0.069 bar = 6.89 kPa.
psig: Pounds per Square Inch Gauge. Pressure in pounds per
square inch as displayed by a gauge calibrated to zero when
open to the atmosphere.
receiver tank: A refrigerant storage device included in
nearly all Thermo King units.
refrigerant: The medium of heat transfer in a refrigeration
system which absorbs heat by evaporating at a low temperature
and releases heat by condensing at a higher temperature.
refrigerant oil: A special oil used to lubricate compressors in
refrigeration systems.
rpm: Revolutions per minute.
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