PRV on a domestic water supply

have a building that is 16 stories that has two booster pumps in order to provide adequate pressure to the top floor.

Since you have not detailed total height, running length, total flow gpm/m3 required for the whole buolding or line size. Lets presume for the time being and we can calculate accurate later on.Presuming each building height is say 20 ft x 16 = 320 ft total height + 15% losses = 368 ft height/2ft. 3in = 160 psi or 11.0 Bar pressure at pump outlet .

(This is for pump located at ground floor)

is there a reason that prv's are necessary on a system that requires booster pumps because of a lack of systemn pressure

160 psi/ 11 bar is TOO HIGH a pressure for domestic use so PRVs installed to reduce pressure to something like 8- 10 psi else can cause injury to people opening taps for usage.

There are two prv's prior to the pumps. These prv's apparently starved the pumps and damged the seals.

Cannot understand WHY prior?

PRV to be installed after the Pump to reduce pressure from 160 psi/11 bar to 8-10 psi.not before. If you install Prv prior pump you've already reduced the pressure & flow starving the pumps. How come you were still getting the required low pressure from the outlet of the pump at the 16th Floor?

PRVs cannot be installed by pipe size. To size correct PRV you need to know inlet pressure(say 160 psi), outlet pressure (say 10 psi) Capacity - Gpm (Missing). Line Size then is selected to pass the required Gpm at the outlet pressure (say 10 psi) at a reasonavle velocity.

Please check again the Prv location, Make Prv & Size, Pump inlet x outlet size, pump capacity, pump motor HP, oulet main size, requirement water each floor,

maxruperti,

Are you possibly confusing PRVs with RPZs?

(Reduced Pressure Zone back flow prevention devices)

RPZs would typically be installed prior to any pumps, at, or in close proximity to the domestic H₂O service entrance...

possibly? I have not been a the site yet and got this info. 2nd hand. The 2nd hand info. was provided as a proposal for repair naming the prv's not rpz's. i appreciate your feedback and will get back with the results.

Thanks again!

Are you possibly confusing PRVs with RPZs? I think maybe he is.

You are correct. I talked to the supt. of the building and it is an RPZ. It must have gotten clogged and starved the pump. Thanks for the help.

Max Ruperti

Put in a Y- Strainer, drill a hole at the check nut and fit a 1/2" ball valve for periodical blow-down/ week. Include this as mandatory. Install a Flow Switch FS 4-3 ITT McDonnel & Miller/ Equivalent (available at e-bay also) to trip the pump and ring an alarm in event it happens again and starves the pump.

Ducon,

I don't think the flow switch is a good idea. Depending on the usage/time of day, you can have periods with quite a low flow. Instead, install a pressure switch and a pressure gauge. Set the switch for the minimum NPSH (net pump suction head) for the pumps, and put a similar marking on the gauge. Wire the switch as you have indicated. The gauge will give an easy visual check of how the system is doing.

--JMM

Yeah OK as long there is some sort of protection/warning.