Page 320 - Reciprocating Compressors Operation Maintenance

Troubleshooting Compressor Problems 3O5

• The unloader is stuck, holding a suction valve open, and not allow-
ing compression of the gas.
* Gasket failure, at the valve seat, cylinder head, or even in the inter-
cooler.
2. Not enough delivery. More often the complaint is not enough deliv-
ery, rather than no delivery.
The above causes still hold true, but with the added possibility of
valve element failures or valve seat gasket failure.
It must also be remembered that as the system pressure rises, the
delivered capacity of the machine is reduced. Should the compres-
sor be set with a system pressure that exceeds its rating, not enough
air will be delivered to the compressor system. Quite often, the
advertised compressor capacity is erroneously interpreted as refer-
ring to the delivered pressure, rather than suction pressure.
It should be noted that faulty valves usually are the most common
cause of a loss of capacity.

NOISE AND VIBRATION

Another compressor problem is noise and vibration.

Vibration

Possible causes of compressor vibrations are:

• Inadequate foundation
• The compressor is not properly grouted
• Unloaders not functioning correctly
• Excessive pipe strain or incorrect piping design

Noise or Knocking

There is always some noise associated with a compressor in operation.
Sources could include air noise from motor, gas flow in piping, clicking
of valves, and slight belt slap on belted compressors.
"Noise" is often described as a mechanical, or friction-related sound.
However, in compressors reports of "knocking noise" are more common.
Determination of the origin of knocking sounds is generally more diffi-
cult because sound travels through the machine.