Number of sprinklers on a branch line? 1

[carlosgw]

I think there used to be a limit of the number of sprinklers on a branch line (say 8).
It may have been only for schedule pipe sizing.
I can't find the requirment in the current standards (NFPA 13 i.e. 2007).
Is it still there?

 

[skdesigner]

No. You can have as many heads on a line as can be proven with hydraulic calculations.

 

[Sdpaddler50]

I am not a sprinkler designer, and only periodically fire up my hydraulic software, but yes, there is definitely a limit to the number of heads allowed on a branchline.

Use the skew formula to determine this. I have not checked for many years, but it should be in NFPA 13. Its 1.4 x square root of the remote area. Note: I believe NFPA is 1.4, and FM notes 1.2, but i will let you confirm that. For example if you have a 2,000 sq ft remote area, using this formula gives you 54 ft. If you are using 10 ft line spacing, you therefore can have a max of 5 heads per line.

For ESFR, you are limited to 4 heads per line. For the typical 12 head ESFR design area, it is therefore 4 heads on 3 lines.

This is important. Fires dont grow in one dimension. These rules make sure designers are applying remote areas that most closely resemble a someshat cirucular fire growth pattern.

 

[TravisMack]

Sorry, but the above statement by Sdpaddler50 is incorrect. NFPA 13 does not put a limit on the number of sprinklers on a branch line. You can have as many as you can calculate. If I have a gridded system with branch lines 200' long between mains and 10' on center, I am going to have 20 heads on that line. That is not a problem. I can have a tree system as well with any number of heads on the branch line.

There is a practical limit just due to the size of pipe that may be involved. But, NFPA 13 does not have a limit anywhere in the standard on the number of sprinklers per line.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[Sdpaddler50]

Yes, my bad. I was referring to the number of heads than can be calculated per branchline. When the OP said 8 heads, i thought he was referring to remote areas for hydraulic calculations. My mistake.

 

[TravisMack]

No problem. I just wanted to make sure that no one was confused.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com