Pneumatic Controllers & Transmitters

Pneumatic controllers and transmitters are used in industrial automation loops where the process measurement and the control command are conveyed by a pneumatic signal. Typical applications include pressure, temperature, flow, and related process variables, particularly in plants with existing instrument air networks or in areas where extensive field electrical wiring is avoided.

This category includes OMC Series 80 and Series 350 pneumatic controllers/transmitters. Series 80 is an indicating controller/transmitter for temperature and pressure service, intended for machinery and general process control applications. Available control actions include ON-OFF, P, P+I, and P+I+D, with a 75 mm scale width. Series 350 is a high-capacity indicating controller/transmitter for temperature, pressure, and flow control, with the same available control actions and a 100 mm scale width.

Selection between the two series should be based on the measured variable, required scale range, control mode, process response characteristics, and compatibility with pneumatic actuators, valve positioners, or I/P conversion systems. In PID loops, the evaluation should include measurement lag, signal stability, instrument air quality, supply pressure, output linearity, and the dynamic interaction between controller output and final control element.

For installations in hazardous areas, versions are available in accordance with Directive 2014/34/EU ATEX, with reference to Gas Zone 1 and Dust Zone 21. During maintenance, inspection should cover air filters, nozzles, signal lines, leakage points, mechanical indication, scale calibration, and deviation between the measured value and pneumatic output signal.