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 TM 55-1905-220-14-8
4-29. AIR CONDITIONING SYSTEM - MAINTENANCE INSTRUCTIONS (Continued).
(4) Compressor.
(a) The compressor is of the reciprocating type, that is, of positive displacement with pistons moving in a
straight line but alternately in divergent directions. The compressor withdraws refrigerant gas from the
evaporator and delivers it to the condenser at an increased pressure. The pressure is such that refrigerant heat
can be absorbed by sea water at ordinary temperatures.
(b) The compressor is direct driven by a 10 hp, 440 volt a-c, 3 ph, 60 hertz, 1750 rpm motor. The
compressor has a cast iron crankcase and is mounted with the motor on a steel base. General data on the
compressor is tabulated below.
Compressor Data
Carrier Model No.
5F30
Cylinders
3
Bore
2-1/2"
Stroke
2"
Speed
1750 rpm
Capacity
7.8 tons at 40 (4 )
F
C
suction temp and 105
F
(40.60C) condensing
temp
(c)
The compressor has the following features:
1
Force feed lubrication by an oil pump driven directly from the end of the compressor crankshaft.
2
Automatic capacity control which permits unloaded starting and provides automatic operation at
reduced capacities of 6-2/3% and 33-1/3%. The capacity is reduced in step with a reduction in
suction pressure.
3
An external relief valve set to relieve at 225 psi (1551.4 kPa) above the existing suction pressure.
4
An oil pressure safety switch which will stop the compressor if the oil pressure drops below the
minimum required for satisfactory lubrication.
5
A high pressure control switch which stops the compressor if discharge pressure becomes excessive.
6
A low pressure control switch which automatically starts and stops the compressor during normal
operation.
4-842
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