TM 5-3655-210-12
Section XX. REFRIGERATION SYSTEM
4-87. General
driving unit, when the tank pressure exceed the limit of
2953056 psi (20.7385-21.44156 kg per sq. cm). The
a. A conventional commercial refrigeration unit, in
driving unit, through a clutch, turns the counter shaft
the power compartment, limits pressure of stored carbon
which, through another clutch, turns the compressor. As
dioxide to 305 psi (21.4416 kg per sq. cm) in response
the compressor operates, it draws refrigerant in at the
to pressure sensitive automatic controls. The system is
suction port and discharges it out of discharge port.
shown schematically in figure 4-84. During normal
b. The flow of refrigerant and the pressure in the
operation, the driving unit is energized by the associated
evaporator coil is controlled by the expansion valve.
tank pressure control switch. When the tank pressure
This valve is a pressure-regulating device which acts to
rises to 305 psi, (21.4415 kg per sq. cm) this switch
maintain a constant pressure of approximately 5 psi
closes the circuit to the driving unit. If the unit is
When the
operated manually by either driving unit, the tank
compressor reduces the suction pressure
pressure switches are bypassed and do not control
operation of the
1.
Discharge service valve
8. Sight glass
2.
9. Receiver inlet valve
3.
Evaporator coil
4.
Expansion valve
11. Receiver liquid outlet valve
5.
Suction pressure switch (gas and electric)
12. Discharge pressure switch (gas and electric)
6.
Receiver
13. Compressor
7.
Refrigerant
14. Suction service valve
Figure 4-84. Refrigeration flow diagram
4-94