Scotsman FDE474 - Manual (Page 13)

Refrigeration System Operation
The FDE474 uses a forced draft condenser,
capillary tube and hermetic compressor. The
system uses R-134a as a refrigerant. High
pressure, high temperature refrigerant is forced
thru the condenser where it discharges enough
heat to condense. The high pressure liquid
refrigerant then passes thru the capillary tube
which causes a pressure drop in the evaporator.
As the high pressure liquid refrigerant moves into
the evaporator’s area of low pressure, the warm
water and low pressure cause the refrigerant to
evaporate and absorb heat from the metal walls of
the evaporator. After the refrigerant has flowed thru
the evaporator it goes back to the compressor thru
the suction line as a low pressure vapor. At the
compressor the cycle is repeated.
The FDE474 uses a low side pressure control as a
safety, it will shut the system down if the suction
pressure is too low for reliable operation.
System Characteristics:
· Typical Low Side Pressure:
13 - 14 PSIG
· Typical Discharge Side Pressure:
135 - 175 PSIG
· System Refrigerant Charge:
14 ounces of R-134a
FDE474
March 2000
Page 13
Capillary Tube
Dryer
Air Cooled
Condenser
Compressor
Evaporator
Refrigeration System Schematic