FUNDAMENTAL INSTRUMENTATION
& CONTROL SOLUTIONS
performance with integrity

INFINITE STEP CONTROLLERS

The Infinite Step Controller (ISC) is a regulating system whereby the capacity of a reciprocating compressor can be infinitely varied without the necessity of using by-pass control or clearance pockets. It is completely automatic in operation and the compressor capacity is regulated to match a controlling set point. It is a replacement for traditional finger, port, plug, and fixed clearance pocket unloader systems and is optimized by effectively controlling capacity over a wide range of operating conditions.

The principle of the system is to mechanically regulate the closing of the inlet valves on each stroke of the piston and therefore the cylinder output. A high speed hydraulic unloader actuates after the inlet valve normally opens, then restrains the valve from closing for a precise portion of the discharge stroke. Gas is expelled during this portion of the discharge stroke back into the suction manifold, thus reducing the amount of discharge gas. The amount of time that the suction valves are held open determines the degree to which the capacity of the compressor is reduced.

Designed with flexibility in mind, the ISC offers various hazardous area classifications and many additional options to fit any client’s needs.

The ISC is currently available through Dresser-Rand. FICS works with D-R to continually improve upon the design of the ISC to develop an elegant, effective system.

ISC in Stainless Steel Enclosure (with and without Weather Kit)

ISC in Painted Enclosure (with and without Weather Kit)

Interior View of the ISC

Product Gallery:


View the full FICS portfolio

FICS Incorporated
25 Community Drive
Addison, NY 14801
Tele: 607-359-4474
Fax: 607-359-4478