Page 390 - Reciprocating Compressors Operation Maintenance

Safety in Operation and Maintenance 375

ALARM AND SHUTDOWN

Monitors can shut down a compressor if physical operating conditions
change. Vibration switches are one type of monitor. Some others are high
lube-oil temperature, low lube-oil level, low oil pressure, high compres-
sor discharge temperature, low first-stage suction pressure, low or high
discharge pressure, overspeed, high engine temperature and high liquid
level in the gas scrubber ahead of the compressor first stage.
Compressors should have alarm and/or shutdown devices. Shutdown
devices are preferred; they protect the compressor. Note, however, that
shutdowns can cause operating emergencies.
At manned installations, when possible, an alarm should precede the
compressor shutdown. Operators may be able to keep the machine run-
ning by taking specific remedial action whenever alarm annunciations
occur.

COOLING PROBLEMS

Watch for cooling problems. Compressor cylinders are usually water
or antifreeze cooled. Water is used for the intercooler between stages.
The water is supplied from cooling towers, fin fan coolers, or vertical
radiators at one end of the compressor-engine block. Poor cooling water
condition and quality can result in poor heat transfer, plugging of small
ports, corrosion, and increased cylinder operating temperatures. Cooling
towers, because they are not a closed system, will accumulate bugs,
leaves, etc., as well as pieces of the tower material that sometimes circu-
late through the equipment and can create heat transfer problems

__ SAFE MAINTENANCE PROCEDURES RESTATED

Prior to doing any inspection, servicing or disassembly, take the fol-
lowing precautions:

1. Shut the machine down.
2. Cut off the electrical supply from the motor by opening a manual
disconnect switch in the power line to the motor, and tag the discon-
nect switch so it will not be closed accidentally.