mulitple risers fed from one underground supply

[cupcars]

Is there any written code in NFPA or other that states a rule or formula that says multiple risers can be fed from one underground fireline?

I've never been questioned on this practice until now, nor can I find anything to back it up. I have an existing 500,000 sqft warehouse bldg that has 12 sprinkler systems fed by 12 UG firelines (built in 1974). The UG needs to be replaced. It's a 10" loop around the building w/ fire hydrants & fed from a firepump taking suction from a water storage tank. the 12 systems are fed off of the 10" loop with their own 8" fireline. In 2 places of this building there are 2 risers next to each other and they each have their own 8" UG fireline.

We wanted to feed both risers from one new UG fireline. The local fire marshal said we could do this if we could prove it will work. As stated above I cannot find anything that specifically addresses the number of risers off of a single underground fireline.

Thank you for your help!

 

[cdafd]

well, not sure if it is in the book, but yes it will work just show him the hyraulic plates on each riser.

I hope he understands that if there are more than a few heads going off, there are bigger problems

also, in away it is already happening, in that the outside feed main is feeding multiple systems, just off of more than one tap, instead of doing it the easy way and running one in and supplying multiple risers.

nfpa 13 2012 edition, should be in prior ones also,

If you have the handbook or can get a copy of the page look at 23.1 and the commentary with it, I know the commentary is not code

also, he can go for an interpratation from nfpa for free


also you have the same condtion most of the time when you have a fire pump, supply comoes in, hits the pump, than normaly the pump feeds more than one riser

do they have a lowes or home depot in the town??

check fiqure A.8.16.1.1 nfap 13 2012 editin shows a wet and dry system being fed by one underground

good luck

 

[YankeeOSU]

Also remember that NFPA 13 only requires designing sprinkler systems for a single fire event. Therefore, even though there are multiple systems on a singer riser manifold, only one system will operate per the code. As long as all systems are hydraulically compliant, you are fine. Provide calculations for all systems acting individually as your justification.

 

[cdafd]

Yes should be one event, but say in a warehouse with multiple systems may get unlucky and the fire hit where one system ends and another starts
One head fuses on one system and another head fuses on another system
Hopefully you do not have to many heads open

 

[SprinklerDesigner2]

Actually better if the fire does open up heads on adjacent systems.