Rotary Screw Controllers

Rotary Screw Controllers > AirStarPD

AirStarPD is an aftermarket local controller designed to manage one Rotary Screw or Reciprocating air compressor for energy efficiency, performance, and machine safety.

Built on the Allen Bradley MicroLogix 1400 PLC platform, designed to meet all NEC standards, all of the components are housed in a NEMA 12 or an optional NEMA 4X enclosure and offer six standard analog inputs (expandable to eighteen), ten digital inputs and six digital outputs.

The processor has a native Ethernet port that connects to the Color HMI with an optional 5 port Ethernet switch to any other Ethernet compatible device. Modbus communications are also available. The HMI serves as the operator interface for all machine control functions, set-point entry and modification, variable monitoring and event history. The data table is configured to 3PX standards for easy access from the 3PX-Backbone data concentrator for master control (sequencing) solutions and SCADA for remote monitoring.

Air Compressor Controls


  1. Elaborate HMI functionality allows complete configuration, tuning, troubleshooting and operation of the compressor.
  2. Familiar Allen-Bradley modular PLC platform that can be easily supported. No proprietary parts are used.
  3. Support whether on-site, by phone or modem connection is prompt, effective and available around the clock.
  4. Documentation thoroughly addresses set-up, tuning, troubleshooting and operations.
  5. Ethernet communications are native and Modbus is optional for connection to any third party DCS, MIS or SCADA systems.
  6. Plug and Play kits available for fast installation in your existing enclosure.
  7. Variable Speed Drive control is optional for Rotary Screw Compressors.
  8. Compatible with 3PX-Backbone which permits electronic integration with numerous third party controllers.

Sullair Rotary Screw Compressors

Rotary Screw Controllers > AirStarPD SAS

As part of our AirStar family of controllers, Case has developed a unique control scheme for Sullair two-stage, rotary screw compressors, AirStarPD-SAS. This solution turns the problematic spiral valve into an asset, making the compressor very responsive and accurate by taking direct control of the inlet and spiral valves from the PLC.

  1. Increased accuracy following demand changes – PID loop controlled, allowing tuning to plant specific demand.
  2. Increased efficiency by fully utilizing the spiral valve thereby minimizing the use of the inlet valve throttle.
  3. Further improved efficiency with coordination of multiple compressors with Case’s AirMaster™.
  4. Reduced maintenance by eliminating pneumatic solenoids, shuttle valves, regulators and filters.
  5. Uses an Allen Bradley PLC for improved reliability, flexibility and supportability.