Operation: Refrigeration - Scotsman FME1200R 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
LIQUID LINE
KING
VALVE
RECEIVER
December 1995
NME950R & FME1200R
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