Why would you want "a way out"? At 5'-0", that pipe will be bouncing like a pogo if it goes off, likely smashing the sprinkler into the rack frame or whatever comprises the shelf above. 9.2.3.4 doesn't apply because it's for branch piping, not arm-overs. If you try to make your in-rack lines into a main, I'd make you sway brace it.
Steve Leyton -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Cahill, Christopher Sent: Tuesday, January 14, 2014 12:52 PM To: [email protected] Subject: Branchline vs Armover Unsupported Length So we have a definition of an armover and branchline. Then we move to NFPA 13 '13 9.2.3.4 and 9.2.3.5 for unsupported length. We have a double row rack with heads between 2' and 5' on center in the flue and on the faces (don't ask, highly unique issue). Contractor ran a line down the middle and 'arms over' to each face sprinkler. The armover is 1.5" pipe 4'3" long. Seems 9.2.3.5 applies and the limit for a hangar is 2'. But really? Why can't we use the 5' under 9.2.3.4? To me it's absolutely clear this is an armover under the definition and they need a hangar. Now if there was any place to put a hangar I'd not even ask this question. Can anyone think of a way out and allow the 5'? Seems to me the 2' could/would/should apply only to drops or sprigs where there is additional weight on the armover. When at the end of an armover and the only thing there is an rc and a head then that should be the 5' (in this case). Why even have 9.2.3.4 as the last head on a BL isn't that an armover so you can never really use that section? Chris Cahill, PE* Senior Fire Protection Engineer Burns & McDonnell 8201 Norman Center Drive Bloomington, MN 55437 Phone: 952.656.3652 Fax: 952.229.2923 [email protected]<mailto:[email protected]> www.burnsmcd.com<http://www.burnsmcd.com/> Proud to be one of FORTUNE's 100 Best Companies to Work For *Registered in: MN _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler .org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
