Page 377 - Reciprocating Compressors Operation Maintenance

362! Reciprocating Compressors: Operation and Maintenance

An analysis of this sort was discussed in Chapter 5. It was noted
that piston ring leaks can be detected by placing an ultrasonic micro-
phone in the middle of the cylinder. Scuffing of piston rings or rider
bands will show on the scope. A piston that is loose on its rod will
show up at the end of the re-expansion and the end of the compres-
sion event.

It is obvious that reciprocating compressor maintenance programs
should include predictive and preventive maintenance elements. Notice,
again, that predictive maintenance alone is not enough. It would be fool-
hardy to completely depend on lubricating oil analysis and vibration
monitoring to determine maintenance schedules for compressors. We
must take effective practices from both types of programs and merge
them into an overall preventive maintenance program.

INTEGRATED CONDITION MONITORING SYSTEMS

Figure 6-5 shows an integrated condition monitoring system. Com-
prised of modules that track several relevant parameters, the system can
transfer data to a computer in two ways:

• Digitally, via direct connection to the process computer, or:
• By direct link initially connecting to data manager modules that
make it feasible to view both static and/or dynamic data.
VALVE TEMPERATURE MONITORING

A modern 32-channel temperature monitor provides increased produc-
tivity and efficiency. The monitor detects changes in valve condition by
using differential measurement of valve temperatures. This allows you to
make shutdown decisions based on real machine conditions rather than
preset maintenance schedules. Reduced machine maintenance cost is also
a benefit of this system. Temperature trends can be used to schedule
maintenance to minimize downtime and to provide information to help
diagnose problems more quickly. Parts can be changed out as needed
instead of "across the board" at scheduled intervals.
The 32-channel temperature monitor is designed for measuring valve
suction and discharge temperatures on reciprocating compressors. A bad
valve will typically be a few degrees warmer than the other valves in its