Problems with valve positioners
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The control valve cannot be fully closed because the valve positioner always outputs the maximum value. How should this sentence be understood?
This post was last edited by zxb1990 on 2015-8-24 at 16:56. I don’t understand what’s going on – the control valve cannot be fully closed, and the output of the positioner is at its maximum value (for air-operated valves), which indicates that the output from the positioner is correct. There are many reasons why a control valve cannot be closed properly, such as internal leakage, the valve getting stuck, incorrect output from the actuator, or issues with air supply pressure.........
I think that’s what the original poster might have meant； The locator already shows the full scale, but the actual valve is not fully closed. If that’s the case, it will need to be manually adjusted again
I don’t understand what this means either; the question and its answer that I saw in the question bank were exactly like this
What is the phenomenon of being unable to shut it off – why is there always traffic passing through? Then it might be that there is a foreign object inside the valve that is causing it to get stuck, or the air supply pressure is insufficient, preventing it from closing properly.
Bro, what are you doing? Why are you still doing exercises?
I don’t understand what that means. Is the control valve single-acting? It will shut off on its own in the case of a single-action air cut-off
If it’s not turned off, it gets stuck; it has nothing to do with the signal
If it can’t be shut down in reality, then use a school valve. If it’s a question from a question bank, well, either the person who created the questions is being stupid and showing off, or there were mistakes made when entering the text. Hehe, when I have time, I’ll show the fellow netizens the weird questions posed by our showy bosses here.
Can it be understood in this way: the positioner has already reached its maximum output, but this does not correspond to 100% of the desired opening degree; therefore, the valve cannot be closed fully