Hussmann Ingersoll Rand User Manual page 182

Unloaders
All 4, 6, and 8 cylinder IR
method used is suction shut-off, whereby the suction-side gas flow is shut off from a
bank of cylinders by means of a control piston (unloader).
The following combinations are possible:
4-cylinder
6-cylinder
8-cyliner
When using unloaders on low temperature applications, a head-cooling fan is required.
For more details on unloader operation refer to Mechanical Design – Section 6 of this
manual.
Application Guidelines
Impact compressors are available with capacity control. The
50 %
66% 33%
75% 50%
2