In the food and beverage industries it is essential that valve position is monitored and controlled accurately and reliably in order to ensure consistent standards of product quality and safety. This article explains how this can be done. Download Valve monitoring and control in the food industry
When a single valve position monitoring device does not provide all the functions required, tandem or even triple mounting one or two additional devices can be the answer.
K Controls distributor in Sweden, Gustaf Fagerberg, has reported that this has been done on a number of emergency shut down valves supplied recently to a leading provider of polyolefins, base chemicals and fertilizers.
Please click on the photograph to enlarge. In this case the partial stroke test device gives valve position feedback via a 4-20mA signal but end of travel limit switches were also required. The K Controls 007 Ex ed certified switchbox can be seen next to the P.S.T. unit.
This approach could also be useful if five or more switch inputs are required or if a positioner does not have all the required position feedback functions.