Problem with valve operation when the positioner nozzle is blocked
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There is a gas valve on site; once I turn off the gas supply, the valve will close automatically. Under normal pressure conditions, while I was cleaning the nozzle of the locator, I covered the nozzle, and yet the valve opened on its own. I can’t understand this – covering the nozzle should mean shutting off the air supply, so how could it open by itself? I’d like to ask the experts: have I misunderstood something? It would be best to explain the principle. . .
These are completely different things; turning off the gas supply means there is no power source, and therefore the valve type must be chosen based on whether it operates on air pressure to open or close. And the power source for the nozzle is still available, as well as the output from the locator; therefore, the valve will still move
Blocking the nozzle increases the pressure, so of course it will open
When the nozzle completely blocks the back pressure, the output is at its maximum; hence, the output is the highest!
The back pressure has increased; you need to study the working principles more carefully