Page 158 - Reciprocating Compressors Operation Maintenance

144 Reciprocating Compressors: Operation and Maintenance

is considered a high-speed valve although it can be applied equally well
to low-speed machines.
Plate valves, concentric ring and ported types, are not the most effi-
cient nor the least expensive valves, but they are more widely used than
other types for one reason: flexibility. They can use metal or plastic
plates, can use mass damping, and can be made with many narrow plates
or a few wide ones, and thus can be effective over a wide range of lifts.

Disc Valves

Disc valves find many applications. The geometry varies from a single
small disc in small valves to multiple discs in large valves. They can be
found in applications ranging from a few hundred psi, as in poppet
valves for gas transmission compressors, to over 50,000 psi in poppet
valves for hyper compressors.
The design characteristics of poppet valves for gas transmission ser-
vice are multiple nonmetallic and streamlined sealing elements in single-
or double-deck valves. (See Figure 3-18).
Maximum lift is approximately .300". Springing is provided by indi-
vidual coil springs for each poppet. Early designs used fluid damping via
unvented spring wells. However, experience indicated that this was not a
good idea, and the spring wells are now vented.

FIGURE 3-18. Disc valve with molded nylon-glass poppets (Source: Cooper
Energy Services, Mount Vernon, Ohio).