Regarding the issue with the KOSO valve handwheel
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As shown in the diagram, the air supply collar of a KOSO single-acting pneumatic valve is damaged; it is necessary to shut off the air supply and replace the collar. At present, the valve cannot be closed – its position is at 48%. It is intended to use a handwheel to hold the valve at this position while the collar is replaced by disconnecting the air supply. I would like to understand the principle behind using a handwheel on such valves, and how to determine that the handwheel has indeed positioned the valve at 48%. Will the valve move erratically after the air supply is disconnected? Seeking advice from experts~~~
Isn’t there a scale indicator behind the handwheel?
1. As can be seen from the diagram, this valve is a air-actuated valve; under normal conditions, the handwheel should be in the closed position. 2. Rotate the handwheel clockwise to open the valve; when the handwheel feels resistant, it indicates that the valve has reached its current control position. 3. At this point, reduce the valve’s opening degree appropriately on the DCS (by 2–3%), note that the actual valve position does not change (as shown on the positioner), and further reduce the valve’s opening degree until the output is zero. The actual valve opening degree remains unchanged, which confirms that the handwheel is functioning properly. 4. At this point, the gas supply ball valve can be closed and the ferrule replaced. During restoration, make sure to adjust the valve to its previous position in advance, gradually close it using the handwheel, and pay attention to the actual opening degree of the valve. For the specific structure, see page P15. The above is for reference only.