Fire pump bypass
Fire pump bypass
(OP)
NFPA 20-2007 5.14.4.1 Where the suction supply is of sufficient pressure to be of material value without the pump, the pump shall be installed with a bypass.
Has anyone qualified what "material value" is? Best answer I have received is that if the city supply can provide enough pressure and flow to make 4 sprinklers work, then it is of material value, as most fire are extinguished with one or two heads.
Just finishing a warehouse with 16.8k ESFR pendants and a 1,500 gpm diesel pump. City pressure sits around 45-50 psi static and drops to 30 psi while flowing about 2,500 gpm. Based on height, the sprinklers need minimum 52 psi to operate.
It appears this is a case where the suction supply is not of material value. The 8" pipe and fittings that went in to the bypass, however, are quite valuable.
Anyone install big pumps with no bypass?
Has anyone qualified what "material value" is? Best answer I have received is that if the city supply can provide enough pressure and flow to make 4 sprinklers work, then it is of material value, as most fire are extinguished with one or two heads.
Just finishing a warehouse with 16.8k ESFR pendants and a 1,500 gpm diesel pump. City pressure sits around 45-50 psi static and drops to 30 psi while flowing about 2,500 gpm. Based on height, the sprinklers need minimum 52 psi to operate.
It appears this is a case where the suction supply is not of material value. The 8" pipe and fittings that went in to the bypass, however, are quite valuable.
Anyone install big pumps with no bypass?





RE: Fire pump bypass
I have only left the bypass out when the system is fed from a tank.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
RE: Fire pump bypass
RE: Fire pump bypass
Thanks for the responses, both make complete sense.
Steve
RE: Fire pump bypass
RE: Fire pump bypass
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Fire Sprinklers Save Firefighters’ Lives Too!
RE: Fire pump bypass
Thought it was there if the pump went bad and also if you had to pull the pump for maintence
RE: Fire pump bypass
In most cases, a pump that is connected to a public or private water supply should include a bypass. Only in rare cases, where the pressure available is so low that the water supply is of no value without the pump, should a fi re pump be installed without a bypass. When a pump
is supplied by a suction tank, a bypass is not needed (see Figure A.6.3.1(b) because a suction tank will not provide suffi cient pressure to be of value without the fi re pump operating. The valves on the bypass are required to be normally open so that the attached water supply is available automatically. In this case, “normally open” refers to the valve being in the open position at all times. The bypass valves should be closed only for system maintenance. In some cases, the function of the pump bypass is mistakenly thought to be used only when the fire pump is out of service. This function is not the intent of the standard, because the water from the bypass must be available automatically if the pump fails to start.
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Fire Sprinklers Save Firefighters’ Lives Too!
RE: Fire pump bypass
PM me at my FPSSDave@live.com when you have a minute.
Thx
Dave
Regards
D
A thing moderately good is not so good as it ought to be
Thomas Paine www.ykfireprevention.ca