If you look at the load limit tables from some of the hanger manufacturers, you will notice that the numbers do not always equal 5 times the weight + 250 lbs. This was pointed out to me by a P.E. reviewing a set of plans I had submitted. Subsequent conversations between the hanger manufacturer in question and U/L reveled the following.
U/L has a set of criteria, hangers and hanger devices have to meet in order to be listed. These involve shake tests, pull out, bending moment, twist off and a bunch of others. Any hanger that meets U/L's shake and bake tests gets listed. Now for the kicker, the listed hanger may not and often does not meet the 5 X + 250 criteria. What NFPA 13 says in its own inimitable round about way is this. Use a listed hanger assembly, if you don't then engineer it to meet all of the criteria in 9.1.1.2 (2007). One added point, nothing is specifically listed in NFPA 13. NFPA 13 does give some example illustrations of representative listed product however it does not specifically list or indorse any products. You can't always go be the illustrations either, for example NFPA 13 (2007) Figure A.9.1.1, top row third from the left shows a split ring, neat little hanger especially for sensing line piping and exposed pipe in atriums and the like. Problem is last time I went to order them I could not find a listed split ring from any manufacturer. Now go two spaces to the right, pipe clamps, try to buy a listed 12" pipe clamp can't be done. I could go on but there is real work to be done. Richard L. Mote ET Designer Rowe Sprinkler systems, Inc. ----- Original Message ----- From: "Chris Cahill" <[email protected]> To: <[email protected]> Sent: Monday, June 21, 2010 12:51 PM Subject: RE: Hanger capacity >I have seen recently where the fine print on a load factor already included > the 250 plus 5x. In my case your 300# would actually be 1750# yielding > 300# > useful for our intent. It wasn't what you are working on, just check the > fine print or talk to the mfg. Of course at 300#/5#/ft = 60 ft which is > 4x > over designed if this is the case. > > Chris Cahill, P.E. > Fire Protection Engineer > Sentry Fire Protection, Inc. > > 763-658-4483 > 763-658-4921 fax > > Email: [email protected] > > Mail: P.O. Box 69 > Waverly, MN 55390 > > Location: 4439 Hwy 12 SW > Waverly, MN 55390 > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Todd > Williams > Sent: Monday, June 21, 2010 11:40 AM > To: [email protected] > Subject: Hanger capacity > > I am having to go through some calculations on hangers to see if a > particular truss can handle the sprinkler pipe. The problem is > involving Sammys and since they are not specifically listed in NFPA > 13 (2002), we need to do the calculations. My question has to do > with the swivel rings. > > Section 9.1.1.2 requires the 5x wt of water filled pipe + 250 lbs. > According to the PHD Manufacturing literature I have, a 2" swivel > ring has a design load is 300 lbs. If we deduct the 250, you have 50 > lbs left. Divide that by 5 and you get 10 lbs as the maximum weight > that can be supported. Since 2" water filled pipe weighs 5.17 lb/ft., > the maximum span a 2" hanger can support and meet the NFPA 13 > requirements is 1" - 11". Am I missing something here? > > Todd G. Williams, PE > Fire Protection Design/Consulting > Stonington, CT > 860.535.2080 > www.fpdc.com > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://fireball.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 > [email protected] > http://fireball.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 [email protected] http://fireball.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)
