OPERATION: Refrigeration
Beginning at the compressor, the refrigerant is
compressed into a high temperature gas. The
discharge line directs this gas to the condenser. At
the condenser (air or water cooled) the gas is
cooled by either air or water and it then condenses
into a liquid. This high pressure liquid then goes
through the liquid line to the expansion valve.
The thermostatic expansion valve meters liquid
refrigerant into the evaporator, the volume of liquid
refrigerant depending upon the temperature of the
evaporator.
At the evaporator, the refrigerant enters an area of
relatively low pressure, where it can easily "boil
off" or evaporate. As it evaporates, it absorbs heat
from the evaporator and whatever is in contact
with it (such as the water inside it). After the
evaporator, the refrigerant, now a low pressure
vapor, goes through the suction line back to
compressor, where the cycle is repeated.
CONDENSER
FAN
MOTOR
LIQUID
LINE
THERMOSTATIC
EXPANSION
VALVE
SUCTION LINE
GEAR
MOTOR
COMPRESSOR
DISCHARGE
LINE
Refrigeration Schematic
EVAPORATOR
OPERATION: Performance
Typical Low Side Pressure
•
Air Cooled: 34 - 38 PSIG
•
Water Cooled: 32 PSIG
Typical Discharge Pressure
•
Air Cooled: 220 - 300 PSIG
•
Water Cooled: 245 PSIG
Typical Compressor Amp Draw
•
8 -9
Typical Gearmotor Amp Draw
•
3.1 to 3.5
Superheat
•
5 - 7 degrees
High Pressure Cut Out
•
450 PSIG
Low Pressure Cut Out
•
0 - 4 PSIG
Fan Motor Watts
•
35 Watt
Refrigerant Charge
•
Air Cooled: 24 ounces HP62
•
Water Cooled: 20 ounces of HP62.
NME650 & FME800
February 1997
Page 15
