For pneumatic valves, should the on-site switch feedback be normally closed or normally open?
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Same as above, is it NC or NO at the site? Why, thank you
Depending on the requirements, it depends on what function this valve is primarily intended for; it is usually normally open, but if preventing pipeline leakage is necessary, then it should be connected in a normally closed configuration
First, it depends on what role the feedback switch you use plays. Second, if a feedback signal is to be fed into the controller, it is necessary to determine what signals the controller requires; however, most controllers use normally open switches.
For pneumatic valves, the on-site switch feedback is generally used to indicate the on or off position of the valve (as a signal feedback), so it is necessary to connect it.
Check what signals the DCS requires and match them accordingly; observe the position of the switches on site and align them with those of the DCS
If both can pick it up, then it’s done, right? Since it’s already available and there are no special requirements for the process, just connect them all
Just connect NC or NO according to the valve status....
It depends on the design; the requirement is that it should remain in the open position if that’s the design, or in the closed position if that’s the design – mainly for safety reasons!
NC normally closed/NO normally open are two switch states; you need to ask the DCS system maintenance personnel which signal to use, otherwise the system status will be reversed