Scotsman FM1200R Service Manual page 20

FM1200R
OPERATION: Refrigeration
Beginning at the compressor, the refrigerant
502 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
DISCHARGE
LINE
HEAD
PRESSURE
CONTROL
VALVE
Refrigeration Schematic
LIQUID LINE
KING
VALVE
RECEIVER
November, 1988
Page 20
depending upon the temperature of the
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.
REMOTE CONDENSER
DETAIL OF HEAD
PRESSURE CONTROL
VALVE
THERMOSTATIC
LIQUID LINE
VALVE
SUCTION
LINE
COMPRESSOR
EXPANSION
VALVE
EVAPORATOR