Page 220 - Reciprocating Compressors Operation Maintenance
P. 220
2O6 Reciprocating Compressors: Operation and Maintenance
FIGURE 3-61. Reverse flow unloading device, schematic view (Source:
Hoerbiger Corporation of America, Pompano Beach, Florida}.
As the piston accelerates, it pushes gas in a "reverse flow" back out
the suction valve faster and faster, which increases the drag forces on the
valve plate. These forces will eventually overcome the unloader forces
and the compressor valve will close. At that point, compression will start
with the reduced capacity output associated with that closing point.
By predicting the drag forces based on application data supplied and con-
trolling the unloading pressure, reverse flow regulation becomes possible.
