Page 168 - Reciprocating Compressors Operation Maintenance

1 54 Reciprocating Compressors: Operation and Maintenance

Discharge Valve
Still Open
Discharge Passage
Pressure

Effect of Discharge
Pulsation

Time
FIGURE 3-19. Time-pressure diagram illustrating how pulsations can cause
abnormal valve closing.

MAINTENANCE AND REPAIR OF COMPRESSOR VALVES

The efficiency and reliability of a compressor depend to a great degree
on proper valve maintenance. Valves should be inspected periodically
and worn components reconditioned or replaced.
A guideline for the recommended frequency of valve inspection can-
not be given, because this depends too much on the type of compressor,
the operating conditions, as well as the type of gas compressed.
In new compressor installations, compressor valves should be inspect-
ed and cleaned within the first 1,000 hours. At this time, the wear on
valve plates and seats should already give some indication of the neces-
sary frequency of maintenance.

Valve Failure Groupings

When compressor valve failure analysis is undertaken, effects are
investigated to determine causes. The effects are usually excessive wear,
fatigue, fracture, or a combination of these. They fall into two groups:

1. Environmental effects
2. Abnormal mechanical action