Standpipe sizing 2

[murtazakhan]

Hi everyone,

I am new in the design of fire fighting systems can any one provide me a good reference regarding size of standpipe for different numbers of fire hose cabinets for all classes(1,2,3).

 

[LCREP]

See NFPA 14, everything you need. Also look at what ever building code used in your area as they will/may have exceptions to NFPA 14.

http://www.nfpa.org/codes-and-standards/document-information-pages?mode=code&code=14

 

[murtazakhan]

Sir,
thank you for your reply. NFPA 14 limits the pipe size to 4'' for stand pipe. I want to know how many fire hoses can be served by this 4'' pipe and when i will increase the size of the pipe.

 

[MatthewJWillis]

I am not sure I fully understand the question. The standpipe provides 100psi @ either 1000gpm if the building is sprinkled, or 1250gpm if it is not. There is one 2½" connection @ the top. How many hoses would then be a Fire Ground calculation. The hose lay type and distance would be the determining factor. Depending on how much is needed, the loss thru the hose can be offset by pumping supplemental water through the Fire Dept. Connection.
So if I understand your question, there is really no correct answer as it would be by situation. The size of the standpipe is dictated by 14. If calculations and water prove good, you can use 4". Otherwise thru hydraulics we may determine if we have to run 6". None of that however has to do with fire hoses.

R/
Matt

 

[orator]

Check NFPA 14 section 7.6.
7.6 Minimum Sizes for Standpipes and Branch Lines.
7.6.1 Class I and Class III standpipes shall be at least 4 in.(100 mm) in size.
7.6.2 Standpipes that are part of a combined system shall be at least 6 in. (150 mm) in size.
7.6.3 Where the building is protected throughout by an approved
automatic sprinkler system in accordance with NFPA 13, Standard for the Installation of Sprinkler Systems, or NFPA13R, Standard for the Installation of Sprinkler Systems in Residential Occupancies up to and Including Four Stories in Height, the minimum standpipe size shall be 4 in. (100 mm) for systems hydraulically designed in accordance with 7.8.1.
Also refer section 7.8, 7.10 for minimum pressure and flow requirements for standpipes. Hope this may help you.

 

[murtazakhan]

Wishing all professionals a nice time.

If i have G+4 Building and have 2 1/2'' FHC 6 nos at 4th floor, 3 at 3rd floor and 5 on each 1st and ground floor then what will be the size of individual branches to each floor and of the main riser. the system is of wet standpipe. Plz attached reference tables as well.