Feedback systems for valves and valve actuators - System description
- Dual inductive feedback sensors for pneumatic actuators and valves
- Designed for simple fit to common actuators based on VDI / VDE 3845
- AS-i versions for even simpler and neater wiring
- Position feedback for rising stem valves up to 80 mm
- Permanent valve monitoring for condition-based maintenance
In industrial processes where liquids, air or gases are used, valves are needed for dosing and control. Pneumatic valve actuators are normally used for mechanical positioning. The valve position must be monitored electronically.
Dual sensor for valve actuators
A round target, also called a 'puck', with two metal screws offset by 90° is mounted on the actuator shaft. The screws are located at a different height. A compact dual inductive sensor (type IND) with two integral sensors detects the upper or lower metal screw depending on the valve position and thus the two switch positions. This system operates reliably with no wear at all. It is virtually resistant to external influence and insensitive to mechanical stress such as vibration and shock.
Sensor for rising stem valves
For position feedback on rising stem valves efector valvis is used. Two or three switch points can be set via pushbuttons over a stroke of 80 mm. In addition to the "open" and "closed" positions of the valve, a third position is used for "seat lift" monitoring (active during the cleaning process). Thanks to a resolution of 0.2 mm the sensor detects even very small changes in the position of the valve. The inductive measuring principle guarantees wear-free non-contact operation. Different adapters allow for easy installation of the same sensor on valves of various manufacturers and sizes.
Feedback: Central monitoring of pneumatic as well as manual valves is imperative.