Product Details:

The 55AX-2 is a Nullmatic 55 series pipe-mounted pneumatic controller under Siemens, a discontinued plug-in type pneumatic regulator designed to pair with pneumatic transmitters for throttling control. It supports throttling adjustment range from 2% to 200%, and comes with built-in manual reset function for safety reset after process deviation alarms. It adopts a compact pipe mounting structure and plug-in core design, which makes disassembly, replacement and on-site maintenance much simpler without taking the whole controller body out from the pipeline.

This is a pure pneumatic instrument without electronic circuit board, it relies on compressed air signal to realize proportional control for pressure, flow and liquid level loops. It receives pneumatic input signals from field transmitters and outputs pneumatic air signals to drive pneumatic control valves. Different suffix variants define internal spring range and reset configuration, and 55AX-2 cannot be directly replaced by other models in Nullmatic 50 / 509 series. It works independently and does not need DCS rack or power supply.

The housing is rugged cast alloy, suitable for humid and vibration-prone industrial environments. There are no electronic LED indicators, and operators check the working state through mechanical dial and air gauge reading. The internal air passage is precision machined to reduce air leakage and guarantee stable control output.

Most stocked units are surplus and fully tested units removed from retired pneumatic control skids. Before installation, technicians need to confirm the supply air pressure specification and calibrate the proportional band and manual reset parameters according to the process loop requirement.

Industry Applications: Applied in oil and gas wellhead control, chemical old pneumatic control rooms, refinery auxiliary loops and water treatment pneumatic regulating systems for air signal throttling control.

Note: Confirm supply air pressure and spring range before ordering

This is from our current stock.