As part of its wide range of control valves, this firm offers a range of electro-pneumatic positioners that allow stroke tests to be performed without disrupting the process line. For example, the Type 3730-3 positioner (photo) incorporates an emergency shutdown (ESD) function to enable stroke testing without interrupting the process. It can be mounted on the valve in addition to the solenoid valve, or replace it, and enables the valve to be moved precisely to follow the set point within the working ratio. The partial stroke test is completely integrated into the positioner to detect a sticking valve caused, for example, by corrosion. — Samson Controls (London) Ltd., Redhill, U.K.
Positioners that perform partial stroking
| By Chemical Engineering