Pressure in Fire Water Distribution Lines Higher than Fire Pump Discharge Pressure

[PotashMechy]

Hello,

The facility that I work at has an electric fire pump/jockey pump combination to provide water to our fire lines. The max discharge pressure of the fire pump is 145psi, however the lines downstream of the pump are reading at 175psi (when the pump is at rest). I was wondering if any of you would have any ideas on how this is possible? The pressure reading on the jockey pump controller is 152psi.

Any thoughts would be appreciated.

 

[LittleInch]

Pressure guage is wrong?
Soil temperature high compared to inlet water temperature?
Jockey pump located 15m higher than pressure guage?

Is inlet tank to pump(s) at high level compared to minimum level ( i.e. is 145 psi based on low inlet level?~

Just guesses as you haven't exactly given us much to go on here.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[77JQX]

Thermal expansion

 

[bimr]

Seems like it is the difference in elevation where the readings are being observed. Is the jockey pump at higher elevation? The fire mains should be buried so there should not be much temperature effects.

Is there a pump curve for the jockey pump?

 

[Artisi]

Is there a problem or just curiosity?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[chicopee]

Since the purpose of this jockey pump is to presumably maintain an elevated pressure at 152 psi, then the downstream pressure of the pump at 175psi SUGGEST a difference in elevation of 53 ft(=23/.433).