Operation: Refrigeration; Operation: Performance - Scotsman FME1200 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 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
CONDENSER

OPERATION: Performance

Typical Low Side Pressure
Air Cooled: 34 - 38 PSIG
Water Cooled: 32 PSIG
Typical Discharge Pressure
Air Cooled: 220 - 275 PSIG
Water Cooled: 245 PSIG
Typical Compressor Amp Draw
Single phase = 4.3
Three phase = 2.8
Superheat
5 - 7 degrees
High Pressure Cut Out
450 PSIG
LIQUID
LINE
FAN
MOTOR
NME950 & FME1200
evaporator; warmer evaporators get more
refrigerant and colder evaporators get less.
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.
Refrigeration Schematic
DISCHARGE
LINE
THERMOSTATIC
EXPANSION
VALVE
COMPRESSOR
Low Pressure Cut Out
0 - 4 PSIG
Refrigerant Charge
Air Cooled: 30 ounces HP62
Water Cooled: 24 ounces of HP62.
January 1995
Page 15
SUCTION LINE
EVAPORATOR
GEAR
MOTOR