Operation: Refrigeration - Scotsman FME1204R Service Manual

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 remote condenser the gas is cooled by air and
it then condenses into a liquid. This high pressure
liquid then goes through the liquid line to the head
pressure control valve, into the receiver, through
the liquid line valve and then through 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; warmer evaporators get more
refrigerant and colder evaporators get less.
Refrigeration Schematic
Discharge
Line
Head
Pressure
Control
Valve
Receiver
Liquid Line
King
Valve
January 2000
NME954R & FME1204R
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.
System Information @ 90
·
Suction pressure: 35 PSIG
·
Discharge pressure: 255 PSIG
·
Minimum Discharge pressure (low temp): 180 PSIG
Compressor Amps
·
3 Phase - 2.8
·
Single Phase - 4.3
Detail Of Head Pressure
Control Valve
Liquid Line
Valve
Suction
Line
Compressor
Page 19
o o
F. air and 70 F. water.
Remote Condenser
Thermostatic
Expansion Valve
Evaporator