Fire Pump Pressure Head

In 1991 the new fire pump at a factory in Dagenham was well capable of delivering 135psi. Unfortunately for the individual carrying out the commissioning, for the factory fire prevention manager, for the fire/security operations manager, for the shift fire/security operations supervisor and for the site utilities maintenance engineer looking on, the cast-iron water mains of some vintage beneath one of the site's main road surfaces were not. Said another colleague shortly after the event: "It was just like Thunderbirds - you know, when the Mole brakes through!" Also a 12" Table D flange is only rated to 100psi when new and the bolts were well rusty.....

"Memories are made of this _{sweet-sweet, the memories you gave to me}".....

Thank you for your response.

But as per NFPA-14 FOR FIRE STANDPIPE, THE MAX. PRESSURE HEAD FOR FIRE PUMP SHALL NOT EXCEED 350 PSI FOR STANDPIPE.

Varies. This from a Google search:

NFPA 20:3-2.1, 1999 edition states "Pumps shall furnish not less than 150 percent of rated capacity at not less than 65 present of total rated head. The shutoff head shall not exceed 140 percent of rated head for any type pump.

Took me longer to cut'n'paste this response than it did to search Google. Suggest you try same for more depth.

I would be surprised if there is a hard and fast number. Your design should dictate the pressure you need, move on from there.

Any how, thank you

my design is require 420 psi

so for this reason i am asking for the max. pressure required as per nfpa

(NFPA-20 DOES'T MENTIONED ANYTHING, BUT NFPA-14 SAY 350 PSI)

Is the fire pump a diesel drive or is it electric? Are you providing a fire system for public fire department access in a building or is it something different?

The application is high rise building and we can use one deisel & one electric.

(N.B THE ONLY AVAILABLE SPACE FOR FIRE WATER TANK IS AT BASEMENT FLOOR)

I think your options are limited since you are dealing with a hose/sprinkler assembly, the way I read my "googled" items says that you need to observe the 350 psig limit. Are you putting the pumps in series and still require the 420 psi on one of the pressure circuits? Something like this:

I'm not a fire system expert, particularly in buildings, but maybe this will put you on the right path. If you're already doing this, how about 3 pumps in series? Maybe use VFDs to stay away from the PRVs as well, I read that too, although I'm not sure how that jives with NFPA 14.