As for a definitive answer to this question, I can not provide. What I can provide is this... there is no direction in the NFPA standard (that I can find) on how to determine a section modulus for spans over 10ft. However...
(1) Adding the 4ft span modulus to the 10ft span modulus does seem to be an acceptable way to determine the 14ft span. I offer this as my logic... Go to the 3ft span for ANY of the pipe sizes and look at the section modulus. Then go to the 6ft span. It is almost exactly 2 times the 3ft span. Then go the 9ft span. It is almost exactly 3 times the 3 ft span. Or go to ANY span and get the section modulus and then go to the span that is double the length. The section modulus is correspondently almost exactly DOUBLE, same as the length! OR add the 10ft span section modulus for 4" pipe shc-10 to the 4ft section modulus for sch-10 and you still get 1.19 The problem will be getting an AHJ to accept this logic and apply it WITHOUT any imperical data to back it up. Ultimately you may have to actually have a section modulus determined or an NFPA technical opinion rendered as to the application of this logic. Thanks, Ray Vance Chief Engineering Tech. Wayne Automatic Fire Sprinklers, Inc. www.waynefire.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Matthew J. Willis Sent: Tuesday, May 20, 2008 12:25 PM To: [email protected] Subject: RE: Trapeze lengths beyond 10'-0" Can you apply the formula and get an equivalent modulus based on not center loading the members? R/ Matt Matthew J. Willis Living Water Fire Protection, LLC. 1160 McKenzie Rd. PO Box 877 Cantonment, FL. 32533 850-937-1850 Voice 850-937-1852 Facsimile [EMAIL PROTECTED] ----- >-----Original Message----- ----- >From: [EMAIL PROTECTED] ----- >[mailto:[EMAIL PROTECTED] On ----- >Behalf Of Randy Knutson ----- >Sent: Tuesday, May 20, 2008 11:05 AM ----- >To: [email protected] ----- >Subject: Trapeze lengths beyond 10'-0" ----- > ----- >Forumites, ----- > ----- > ----- > ----- >I searched the archives and didn't find a discussion on ----- >this topic. ----- > ----- >Here's my question? ----- > ----- > ----- > ----- >Can I extrapolate out beyond the 10'-0" length on the ----- >section modulus required for trapeze in table ----- >9.1.1.6.1(a) '07ed.? ----- > ----- > ----- > ----- >A fitter called this morning wanting 14' trapeze hangers ----- >for 4" pipe. He was placing the main in the wrong ----- >location but it brought up an interesting question. I ----- >noticed that the section modulus has a linear increase ----- >with trapeze length. ----- > ----- >For 4" Sch 10 y=.085x, where y=section modulus & ----- >x=Trapeze length. So, for a 14' trapeze for 4" sch 10, ----- >would a 1.19 section modulus work? ----- > ----- >Do I have to have the initials PE after my name to think ----- >these thoughts? ----- > ----- > ----- > ----- >Thanks, ----- > ----- > ----- > ----- >Randy Knutson ----- > ----- >Shilo Automatic Sprinkler, Inc. ----- > ----- >_______________________________________________ ----- >Sprinklerforum mailing list ----- >[email protected] ----- >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum ----- > ----- >To Unsubscribe, send an email ----- >to:[EMAIL PROTECTED] ----- >(Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
