water demand of hose 1

[crb7]

hi
i have a 13 stories commercial and office building that is partially sprinklered, i want to calculate requirement water flow rate for hose streams. shall i consider 500 gpm for hose stream flow rate? or 1250 gpm because of lack of sprinkler system?
the building is in light hazard.
tnx for ur help

 

[UFT12]

I take it you are referring to standpipes, not just hose streams on sprinkler system. Crucial questions here are

What S/P Class are you designing? From your query I understand it's class I or III.
What is the size of the building?
How many S/P are you installing?

NFPA 14 will give you all the answers. Typically, least favorable riser is sized for 500 gpm and adding 250 gpm to each other to reach 1250 gpm for partially sprinklered building given you have the S/Ps available. If you don't, you don't have to reach 1250 gpm. Also the total water demand is not just the S/P rather a combination of both S/P and sprinklers. See 7.10.1.3.2

 

[stookeyfpe]

UFT12 is spot on. If this is an IBC building the standpipes are required to be automatic. If it's not in the US or Canada the building or fire code in the jurisdiction will prescribe the basic design requirements.

 

[crb7]

tnx guys
7.10.1.3.2 in NFPA 14 said "For a combined system in a building equipped with partial automatic sprinkler protection, the flow rate required by 7.10.1 shall be increased by an amount equal to the hydraulically calculated sprinkler demand or 150 gpm (568 L/min) for light hazard occupancies, or by 500 gpm (1893 L/min) for ordinary hazard occupancies, whichever is less."
my sprinkler demand is 400 gpm, and according to above clause i have to add 150 gpm + 500 gpm (because 150<400). so i have to size my pump for both sprinkler and standpipe system for 650 gpm. am i right? or only water demand of standpipe system is 650 gpm?

2 - 7.10.1.1.1 in nfpa 14 , the minimum flow rate is designed for 500 gpm. is it for all sizes of building? isn't area of building important? i don't get it correctly?

tnx for ur answers

 

[UFT12]

1. How many standpipes you have? For just one vertical the answer is correct.

2. For the most remote standpipe yes. But size of building matters for the rest of the system.

Check carefully all clauses in chapter 7.10.1 and combine them as necessary.