Pressure Reducing Valve, and Further Reduction of Pressure

[Albertdorian]

I am trying to bypass pump station to service and recoat a 200k gallon storage tank, the total head of the system straight thru the bypass connection would be 824 ft, which is about 357 psi at the bottom of the system, therefore I need to reduce the pressure at the bypass with a pressure reducing valve (PRV).

I checked the pressure at the bypass point and I am looking at 185 psi, if I use the PRV I can reduce to 80 psi without running into cavitation problems (According to the cavitation guide published by the manufacturer)

Now, the problem I am having is that there are still 413 ft (178 psi)of head from there to the bottom of the system which will increase my pressure to (80psi + 178psi = 258psi)

My question is; if I want to reduce pressure at the bypass point lower than 80, can I achieve this by installing an orifice plate just after the PRV?

Thanks, everyone. (Please see attachment)

 

[PEDARRIN2]

How about two PRVs in series?

 

[fel3]

Two or more PRVs in series would be my first choice. Depending on circumstances, they could be next to each other, or at separate locations down the hill.


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"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[bimr]

Agree. two PRV's would provide more flexibility. The orifice plate will only reduce the pressure when water is flowing, not when the water is stationary.

 

[Albertdorian]

Thank you for the quick posts.
I found the manufacturer also has anti-cavitation PRV. has anyone used those before?

Thanks

 

[mk3223]

Orifice plate design is cheaper option, or the two or more PRVs can provide the operation flexibility.
But, What if to run the flow with the whole hydraulic pressure of 357 psi at the bottom of the hill without the pump running?

 

[77JQX]

The anti-cavitation PRVs we've used work as advertised, but will have lower full flow capacity than ordinary PRVs. Due to the high pressures, I'd want some insurance against failure of a single PRV, so I'd also install a pressure relief valve or go with two pressure reducing valves in series.