Change the air valve from open to closed
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With the valve core in the correct orientation, and the diaphragm-type control air-operated valve to be changed into an air-operated shut-off valve, what are the possible ways to achieve this?
It’s generally not possible to do it by oneself, as the cylinder needs to be modified
It can only be achieved by changing the reaction force of the actuator
To change the operating mode of current pneumatic diaphragm control valves, it can only be done by the valve manufacturer, or by ordering a new valve.
Theoretically, either the cylinder’s intake and spring need to be modified, or the valve spool and seat need to be changed. Acting-cylinder + acting-type valve seat, or reacting-cylinder + reacting-type valve seat.
If the cam inside the valve positioner is turned in the opposite direction, will this meet the requirements?
The signal can be changed: 4 milliamps corresponds to full open, while 20 milliamps corresponds to full closed
It is necessary to make this requirement clear to the valve manufacturer; the valve’s normal and reverse operation modes, as well as its air-open and air-close functions, have already been designed, and they cannot be changed after the valve leaves the factory.
Swap the direction of the membrane tip; something for support is needed inside, and the manufacturer will provide it if you contact them. I changed the air intake from bottom to top, and I modified the valve on the tooling.