Page 146 - Reciprocating Compressors Operation Maintenance

t 32 Reciprocating Compressors: Operation and Maintenance

A valve must do this directly in the path of the gas stream and is sub-
ject to any entrained liquids, foreign particles, corrosive gases or materi-
als, and occasionally must operate practically covered with sticky or
"gunky" material. It is subjected to all types of destructive forces such as
tension, compression, impact, twisting, bending, abrasion, erosion, and
extreme temperature variations.
If the valve fails to function properly, the compressor cannot supply
compressed air or gas and must be shut down for repair. So, anything that
can be done to improve the operation of a compressor valve also
improves the overall operation of the compressor itself.

Successful operation of a compressor valve begins with sound basic
design to meet the specific requirements of a given installation. The
valve must be adequately maintained and used in a normal manner.

VALVE THEORY AND DESIGN

What Is a Compressor Valve?

Compressor valves are devices placed in the cylinder to permit one-
way flow of gas either into or out of the cylinder. There must be one or
more valves for inlet and discharge in each compression chamber (cylin-
der end).

Bask Requirements of a Compressor Valve

Basically, an automatic compressor valve requires only three compo-
nents to do the job it is required to do:

1. Valve seat
2. Sealing element
3. A stop to contain the travel of the sealing element

However, a valve comprising only the above components installed in a
modern compressor would not fulfill the expected life and efficiency
requirements. Due to the high demands on today's reciprocating compres-
sors, the valves require a much more elaborate design than outlined above.

Modern compressor valves either incorporate or exhibit the following: