It is important to know when not to turn on the reciprocating compressor.
If your system has been shut down for a long period of time .
You are going to start it up again.
Do not energize the reciprocating compressor until the condenser water temperature reaches 45°F or warmer.
This will help prevent damage that can result from liquid refrigerant contacting a cold surface.
Capacity control of a reciprocating compressor can be accomplished.
Directly by varying the speed or by methods designed to allow direct discharge of vapor from a cylinder.
To the low pressure or suction side during the so-called compression stroke.
The capacity control method are:
- This control method uses an external bypass around the compressor to recycle gas from the compressor discharge to the inlet, or to the atmosphere in the case of an air compressor.
The take-off point for the bypass must be downstream of a heat exchanger so that cooled gas will be spilled back to the suction.
If there is no exchanger in the discharge, the bypass must branch into the suction line upstream of an exchanger.
- A cooler may be placed in the bypass line.
In any case, the bypass should tie-in upstream of a suction knockout drum so that any condensate resulting from the expansion cannot enter the compressor.