Company: PG & E
Case #: 25


A reapplication of an existing four throw motor driven compressor unit rendered the original arrangement incapable of meeting the new demand.

Customer's Need:

The customer needed two cylinders to duplicate two existing, identical cylinders.  The four cylinders provided two cylinders for each of two frames for first stage service. In addition, capacity control devices were required to accommodate the predicted varying flow.

ACI's Solution:

ACI traveled to the job site to take field measurements of one of the existing cylinders which was to work with a new cylinder to serve as the first stage. Drawings, patterns, casting and machining resulted in the production of two complete cylinder assemblies. In addition to normal hydro tests, major castings were magnafluxed in accordance with customer specifications.  Unloading was supplied to provide the capacity flexibility necessary to meet the predicted demand. The aluminum piston design associated with this cylinder was essentially a one piece cast design that utilized rubber band style rider rings. The piston design eliminated an integral rider ring stretch over diameter. The rider ring installation tool also served to form the slip over diameter which also closed the otherwise open end of the piston rider ring grooves. As a result, the installation tools are stored on the piston.


Unit performance met the customers specifications and the machine performed without flaw. Delivery and price were less than those of the OEM.