On-off valve Hookup 4

[joji90]

Dear members,

I have a XCV( fail open) and has to be slow opening , the idea is to demolish the old valve and install new one., but when I see the pneumatic hookup of the old valve, I don't understand it, I made a pneumatic drawing from the existing setup but could identify the clouded component and hence couldn't understand the working of the valve. can anyone help please?
Also please check the PDF doc in attatchment for additional info.

 

[joji90]

@fmjalink,@compositepro,@little inch- thankyou all for your inputs.

we decided to change the valve to a single acting as per the PID( dont know why it was double acting in the past) , and decided to hook it up as shown below. strangely, the client doesn't know why there was a accumulator vessel.!! and why it has to be slow opening( we did a new water hammer calc and turned out to be fine!)
hence decided to connect the old accumulator back and include a vent throttle valve to control the valve opening time if needed in future.