Page 224 - Compression Machinery for Oil and Gas

Reciprocating Compressors Chapter 5 213

FIG. 5.30 Head-end variable volume clearance pocket. (Courtesy of Ariel Corporation.)

FIG. 5.31 Manually operated variable volume clearance pocket. (Courtesy of Ariel Corporation.)

A version of this device is automatically actuated, using electric or
pneumatic motors, or by using hydraulic actuators, and is becoming more
common. The advantage is this device can be tied directly to a control system
allowing the clearance, and therefore the capacity, to be adjusted completely