Ron, I've been told by someone who I trust implicitly that there's a substantial number of things in the standard which are there because "Chet said it sounded right to him." I'm not making any value judgment on this just relating what I was told. I'm like you, in that I look at some of that stuff, not just in hanging and seismic, but throughout the book, and I ask "out of curiosity, how did they come up with that?"
A couple of others which come to mind are the density numbers for LH, OH, and EH occupancies. I know I could probably find why it was changed when OH went from three classes to two, but I just don't have the time nor desire to look it up. With all that said, it's worked pretty darn well, though. It is what it is, I guess. PARSLEY CONSULTING Ken Wagoner, SET 760.745.6181 voice 760.745.0537 fax [email protected] <mailto:[email protected]> e-mail www.ParsleyConsulting.com <http://www.ParsleyConsulting.com> website Ron Greenman wrote: > I don't know if that extra 250 lbs was really for the fitter of old to > grab onto or if that is just the story we've been telling each other > for so long it's become the common "truth." If the truth then we'd > better reassess it in light of current times. First we need to add > about 100 lbs if it's to meet the criterion of the story but, and > probably more telling, I think OSHA (or your local version) might be > concerned if we're actually telling our fitters to grab the piping if > they fall. Adding the 250 lbs is the rule. Why is unimportant unless > the hanging and bracing committee wants to revisit the rule. If > research were to suggest that the "story" really is the "truth/reason" > then maybe we can just let it go. And what really is the criteria for > any of this? Is it just a left over from the days of "I remember when > 13 fit in your back pocket" versions of 13 that only addressed pipe > schedules and other good, safe rules of thumb? Who decided, when was > it decided, why is it (has it been constantly evaluated as valid--too > much or too little), what values is it based on, etc.? In any event at > this stage of sprinkler design development I'd worry about adding the > 250 lbs to the calculation but not because a fitter might grab it. He > might just as easily reach out for the 1/2 inch conduit. Better to > have him properly tied off. Saves a heap of change on OSHA fines, > lawsuits and possible criminal charges. > > On Tue, Aug 4, 2009 at 8:09 AM, Todd Williams<[email protected]> wrote: >> Something to think about. Hangers are designed to take 5x wt of water >> filled pipe +250 lbs. The 250 is supposedly to support a fitter if he >> had to grab on to it in an emergency (or so I have been told). Has >> anyone looked into if CPVC pipe could support a 250 lb person, even >> with hangers designed for it? >> >> >> >> At 10:54 AM 8/4/2009, you wrote: >>> Why not just calculate the modulus using the methods in NFPA 13 and then >>> size your trapeze pipe accordingly. Or, as George said, use the values >>> for steel and just have some oversized trapeze bars. >>> >>>> Assuming CPVC weighs less than steel pipe, use values for steel and >>>> you're >>>> safe. If you're near a head, make sure you're protecting against upward >>>> movement if needed. >>>> >>>> When we get into bar joist construction, we often switch to steel since >>>> hanging issues often make it a better installation all around. >>>> >>>> glc >>>> >>>> -----Original Message----- >>>> From: [email protected] >>>> [mailto:[email protected]] On Behalf Of >>>> [email protected] >>>> Sent: Tuesday, August 04, 2009 9:03 AM >>>> To: [email protected] >>>> Subject: Re: trapeze hanger, PVC >>>> >>>> Greg, >>>> If you are in a position to require trapeze hangers on cpvc,maybe >>>> you need >>>> to reconsider using steel pipe for stability and rigidity.Just a >>>> thought. >>>> ---- Greg McGahan <[email protected]> wrote: >>>>> Have we ever discussed the use of trapeze hangers for cpvc piping? >>>> Specifically, modulus requirements etc? >>>>> Greg McGahan >>>>> Operations Manager >>>>> >>>>> Living Water Fire Protection >>>>> 1160 McKenzie Road >>>>> P.O. Box 877 >>>>> Cantonment, Florida 32533 >>>>> (850) 937.1850 | Fax (850) 937.1852 | Cell (850) 554.3231 >>>>> [email protected] >>>>> >>>>> >>>>> _______________________________________________ >>>>> Sprinklerforum mailing list >>>>> http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >>>>> For Technical Assistance, send an email to: >>>>> [email protected] >>>>> >>>>> To Unsubscribe, send an email >>>>> to:[email protected] >>>>> (Put the word unsubscribe in the subject field) >>>> _______________________________________________ >>>> Sprinklerforum mailing list >>>> http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >>>> For Technical Assistance, send an email to: >>>> [email protected] >>>> >>>> To Unsubscribe, send an email >>>> to:[email protected] >>>> (Put the word unsubscribe in the subject field) >>>> >>>> _______________________________________________ >>>> Sprinklerforum mailing list >>>> http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >>>> For Technical Assistance, send an email to: >>>> [email protected] >>>> >>>> To Unsubscribe, send an email >>>> to:[email protected] >>>> (Put the word unsubscribe in the subject field) >>>> >>> >>> -- >>> >>> >>> _______________________________________________ >>> Sprinklerforum mailing list >>> http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >>> For Technical Assistance, send an email to: >>> [email protected] >>> >>> To Unsubscribe, send an email >>> to:[email protected] >>> (Put the word unsubscribe in the subject field) >> Todd G. Williams, PE >> Fire Protection Design/Consulting >> Stonington, Connecticut >> www.fpdc.com >> 860.535.2080 >> _______________________________________________ >> Sprinklerforum mailing list >> http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >> For Technical Assistance, send an email to: [email protected] >> >> To Unsubscribe, send an email to:[email protected] >> (Put the word unsubscribe in the subject field) >> > > > > > ------------------------------------------------------------------------ > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.5.392 / Virus Database: 270.13.43/2281 - Release Date: > 08/04/09 05:57:00 > _______________________________________________ Sprinklerforum mailing list http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
