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Combined system flowrate and standpipe locations

Question asked by arslanzaidi on Jul 9, 2018
Latest reply on Jul 13, 2018 by maron.alexey@gmail.com

Hello,

 

I am confused in selecting the required water supply demand and standpipe locations for firefighting system in a building. Building is partially sprinklered; 2 car parks and 3 commercial floors, remaining non-sprinklered are 7 residential floors. Occupancy is light and ordinary hazard. Layout of a typical commercial floor is attached herewith.

Building has 6 stairways in total but 4 of them are emergency. Architectural layout is attached. I plan to use combined sprinkler system Class I using pipe calculation method.

 

1. Do all 6 stairways require standpipes? or I can use 4 stairways (which are circled in the attached layout). NFPA states that every stairway requires a standpipe, but thats only about emergency exits I guess. If I use the 4 standpipes, I do not need additional fire hose cabinets inside the building as 150 ft and 200 ft travel distances can be met using 4. However, these stairways start from the Ground floor till roof. The other 2 stairways (at the top side of building) run through all basements till roof.

 

2. Along with Q.1 as stated above, is there any other location(s) too which I must consider for FHCs or standpipes? What about the Entrance? (I read the section but did not get a clear picture of what NFPA wants)

 

3. Can I use 1250gpm pump for this arrangement (max. acc to NFPA 13) of 4 standpipes or I have to add 500gpm (for ordinary hazard, partially sprinklered buildings) to this acc to NFPA 14:

 

"7.10.1.3.2 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."

 

Wont 1750 gpm be too big for this scale of building?

 

 

4. Lastly, 100 psi min. requirement is at the valve or end of hose pipe (at nozzle)? As I read somewhere, a 150ft hose pipe also induces considerable pressure loss should it be considered while doing pump head calculations?

Thanks in advance for all the help you people can give.

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