Positioners are part of a control loop.
The loop consists of;
- An instrument
- A Controller
- A Positioner
- An actuated Valve
The Instrument measures the process and provides an output proportional to the process on a scale e.g. 4-20mA (which is most common)
The Controller receives the Instrument signal and compares it to the set-point (desired signal), then sends a derivative signal to the Positioner. This signal commands the Positioner to move the Actuated Valve in the direction which will drive the process to the set-point position.
The Actuated Valve responds to the signal from the Positioner and moves.
The Instrument measures the process and confirms that the set-point position has been reached.
Positioners generally use 3-15psi, 0-10 Ohm or 4-20mA control signals with 4-20mA becoming the global standard.
Positioners which provide diagnostic feedback to the control room of Valve response and condition are termed SMART Positioners.
Our range of Positioners includes the following:
- Safe Area 3-15 psi and 4-20 mA versions
- Intrinsically Safe
- Explosion Proof
- Stainless steel
- Integral limit switches for feedback
- Integral 4-20mA transmitters
- HART capable devices
- On-board diagnostics
- High temperature versions
- Low temperature versions to -40C
- Fieldbus options including Profibus and FF
- Partial stroke facility local and remote
- Gauge blocks
- Volume booster
- GOST-R and RTN
- Mounting kit design using CAD for linear and rotary actuator designs