Page 341 - Reciprocating Compressors Operation Maintenance

326 Reciprocating Compressors: Operation and Maintenance

BELT DRIVES

On compressors that are belt driven, the V-belts will require some
attention. Figure 5-2 is a guide for troubleshooting V-belts.
MOTOR CONTROLS

Troubleshooting of motor controls involves a point-to-point mechani-
cal and electrical inspection of the motor control equipment. Table 5-4 is
a guide for troubleshooting motor controls.

DIAGNOSTIC TESTS

Diagnostic testing is likely to pinpoint the source of a compressor mal-
function.On small air compressors, proceed as follows:

To TEST FOR UNLOADER BYPASSING

Remove suction filter. If pulsing is noted when hand is held over the
air intake, the unloader is bypassing.

Remove filter for a short while and note if compressor output increas-
es. If filter is clogged, clean with air and by washing with a caustic solu-
tion. Never use kerosene or gasoline for cleaning filters. Doing so is like-
ly to cause an explosion.

INTERCOOLER PRESSURE

The pressure in the intercooler is a good indicator of compressor per-
formance. At 100 psig discharge (atmospheric suction), the intercooler
pressure is normally about 27 psig. If intercooler pressure is low, look for
defective valves in the first stage. If intercooler pressure is high, look for
defective valves in the second stage.

COMPRESSOR KNOCKS

Virtually all compressors will have an inherent gas noise, or pulsation.
Intensity and sound patterns may be more or less pronounced, depending