Problems with self-acting control valves
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How to adjust this control valve without scales or pointers? Did the manufacturer forget to install it, or is it not needed?
Check the pressure gauge behind the control valve to make adjustments.
Once the pressure gauge is adjusted, in theory there’s no need to make any further changes, unless the required performance standards aren’t met. After all, it’s a self-acting device; its only purpose is to maintain a constant pressure before or after the valve, relying solely on springs or diaphragms for sensing. Check out the principle behind it
Once it’s properly adjusted, it generally doesn’t move anymore; if adjustments are needed, it’s best to send it back to the factory for the supplier to make them.
Pointers and scales can be added by yourself, but they are not very useful for self-acting control valves. The control target for such valves – the pressure at the upstream or downstream end – is clearly indicated by the corresponding pressure gauge; it is not necessary to know exactly how much the valve is open, as long as it is known that the controlled pressure meets the required standards.
Yes, no manual intervention is required, and there’s no connection to a DCS either; the valve opening degree isn’t important – as long as the desired adjustment level is achieved
This self-acting control valve is quite advanced
I’ve really never seen this before; what’s its use?