Checking and the maintenance of the dissimilar check valves

[enguest]

Dear all,

Currently I am working on the project, where we installed two dissimilar check valves to protect system from the back flow. One of our concerns now is how to do a regular check of these valves without disconnecting them. I would appreciate if you could advice me a standard which I can use for this issue.

Thanks in advance.

 

[Compositepro]

If it is important to prevent back flow then you must use a back-flow-preventer valve, not two check valves. These introduce an air-gap if upstream pressure is not greater than downstream pressure.