Don't agree. With that logic we couldn't put wet drops in on armovers. The head is still 11.2 no matter if you connect it to sched 40 or XL or have a linkage mechanism in the pipe. The only thing the cut sheet does is a calculation for you. We don't know the effective diameter of the inside of the barrel so we really can't do this calc. It would be the equivalent of 5.6 heads having a quick reference guide for a variety of pipe drops and fittings included. Which is what we do a lot in coming up with an equivalent K for drops and referencing that in balancing over the 5.6 (or whatever k).
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, May 04, 2009 1:30 PM To: [email protected] Subject: RE: Preaction: single vs double Travis, You may be opening a can of worms trying to use dry pendents in this area. What is your ceiling density? Section 12.1.13 (NFPA 13 2002) has specific K factor requirements for different densities in storage occupancies. With dry pendents, the K factor decreases with length of the head. I pulled up the Tyco DS-2 K11.2 dry pendent sprinkler as an example. If you have 12" of insulation and are required to be 18" above that, you are looking at a 30" dry pendent. The actual K factor for a 30" dry pendent is 10.6. That would not meet the letter of the requirement of 12.1.13.3. I actuality, you would probably be meeting the intent, but could create an issue depending on who is reviewing it. It would probably make more sense to change the requirement in NFPA 13 from K factor to orifice size, because that is in reality what the makes the difference. Todd _______________________________________________ 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)
