Is it necessary to cut off the instrument air supply when operating the pneumatic control valve with an on-site handwheel?
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Guys, I have a question: when operating a pneumatic control valve using the local handwheel to open or close it, is it necessary to cut off the instrument air supply?
When operating the local handwheel of a pneumatic control valve, it is usually necessary to cut off the instrument air supply to prevent pressure signals from interfering with manual operation. .
It is recommended to follow the valve’s instructions for operation, as valves vary in their design; some require manual switching while others do not. For reference.
For single-acting control valves, the air supply needs to be turned off; for double-acting control valves, the balance valve is opened – it doesn’t matter whether the air supply is turned off or not
The gas supply is turned off; manual operation should be easier
It’s not necessary; it’s just that operating it manually with a gas source is rather labor-intensive. It also depends on whether the valve comes equipped with a gas lock valve, but it’s fine to turn off the gas supply as well – it makes things easier.