Fire Pump Generator Back-Up 1

[NCDesign]

I am a trying to 'ballpark' a backup generator for a 19 story high rise. Eight stories will be parking deck the rest will be office and retail space, approximately 30,000 ft2 per floor. Can anyone give me a ballpark size for the fire pump so I can finish guesstimating the generator sizing?

 

[TravisMack]

Your standpipe system is going to drive it. How many exit stairwells do you have. If you have 2 stairwells, you are going have a 750 gpm demand at the pump discharge. You need to provide 100 psi AT THE HOSE VALVE. So, figure your elevation pressure. Add the 100 psi. Include about 15 - 20 psi for friction loss, plus any valves with large pressure losses (backflow preventers) on the system side of the pump, and you will be able to determine what the pressure needs to be at the system side of the pump.

Subtract what is available from the city at your demand. Leave 10 psi or so for margin and there you have it: a rough estimate of your pump pressure and flow.

Good Luck!!!!

 

[NCDesign]

That was exactly what I needed. Thank you.