Regarding control valves

Connect an ammeter in series with the circuit to check whether current is flowing; verify that the positive and negative connections are correct, and also check if there are any wires connected to ground. Ensure that the air supply is active. Use a manual air controller to send signals on-site to assess the accuracy of positioning. As for the other valve bodies, you’ll need to analyze them once you’re on site

Check for positive and negative pressures, check the air source, check the diaphragm; determine whether it is a gas-shut valve (it seems the term used in forums is air-open valve)

First, check whether the 20mA signal has reached the input terminal of the control valve. Next, verify that the air supply pressure meets the requirements. Then, check if the valve positioner is functioning and whether the air supply pressure is reaching the diaphragm of the valve. Finally, inspect the valve seat and the valve stem.

There are many possibilities: air source pressure, solenoid valves, solenoid coil, and so on··

First, check if the wires are connected incorrectly, then verify that the air supply is functioning properly, and after that, test whether the signal is reaching the control valve actuator

It’s possible that the valve is stuck, or that its positive and negative terminals are reversed. Check whether there is any leakage in the gas supply line, and see if the valve actuator is functioning. At the site, use a 475 handheld transmitter to send a 4 to 20 milliampere signal to determine whether the valve operates. Or the handwheel mechanism has not been moved to the free position. That’s all I know!

A salute to my colleagues, scholars* – OK

Start with these points: whether the valve can be operated manually, whether the air supply is connected, whether the valve has been switched from manual to automatic mode, whether there is an output signal, and whether the actuator is functioning

Hehe, I still can’t see the replies from the friends above. I won’t watch it either; I’ll just talk about my approach. There are various situations in which the field valves do not respond to the signals sent from the control room. First, check whether the electrical signal on the side of the on-site control valve is reaching the site; this can be done using a multimeter. It is also necessary to check whether the air supply for the control valve is properly prepared, such as the pressure and flow rate of the instrument air, whether the instrument air valve is open, and whether there are any impurities in the air circuit that could cause blockages. Next, check whether the auxiliary components of the control valve are in good condition, such as whether the electrical converters and valve positioners are functioning properly. The steps and procedures for this inspection vary depending on the type of instrument, so I won’t go into detail here. Finally, it is necessary to check whether the control valve itself is in good condition – for example, whether the valve stem is firmly connected to the actuator’s push rod, and whether there are any impurities inside the valve that could cause problems. Actually, despite all this talk, the on-site handling isn’t that complicated; experienced personnel can basically quickly determine the cause and location of the fault and resolve it promptly.