I can only point to the same code, and interpret "used" literally. I hope I am wrong about this-- if so I would not feel bad about having left a box or two of heads off remote lines :)
-----Original Message----- From: Chris Cahill [mailto:chr...@sentryfiremn.com] Sent: Tuesday, April 20, 2010 2:30 PM To: sprinklerforum@firesprinkler.org; bcasterl...@fsc-inc.com Subject: RE: Calc Area Could you point to a code section or any materials that suggest if you end up at 1640 you need 49'? Yes 02'-14.4.4.1.1.1 has the term 'used' but that's in reference to the area used out of the tables not the area actually used in the calc. If you choose an area of 0.098/1640 (used) for light hazard by sliding up the curve then yes you are correct 49' would be required. If I choose 0.1/1500 (used) and because I ended up on the first try at 1499 sq.ft. I added another head resulting in 1640 sq.ft. I still only have to calculate 46.5'. I respect you may choose to do more when you go over 1500 sq.ft. But I don't think it's actually required by code. Chris Cahill, P.E. Fire Protection Engineer Sentry Fire Protection, Inc. 763-658-4483 763-658-4921 fax Email: chr...@sentryfiremn.com Mail: P.O. Box 69 Waverly, MN 55390 Location: 4439 Hwy 12 SW Waverly, MN 55390 -----Original Message----- From: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Brad Sent: Tuesday, April 20, 2010 2:02 PM To: sprinklerforum@firesprinkler.org; b...@firebyknight.com Subject: RE: Calc Area Why average anything--the actual dimensions are right there-- the thing I am stressing is if you end up with 1640 SF area USED, go back and make sure 49' does not put you more than half way to ANOTHER head on the line-- the 1.2 rule is for area USED, not minimum required area. -----Original Message----- From: A.P.Silva [mailto:silva...@shaw.ca] Sent: Tuesday, April 20, 2010 1:51 PM To: sprinklerforum@firesprinkler.org; b...@firebyknight.com Subject: RE: Calc Area The critical factor is the length of the design area. Not the number of heads. For 1500 RA and 1.2 shape factor this is approx. 46.5 feet. So taking your example, it will be 5 heads per line, whichever side is the most remote. Your method will work, but maybe not always. Say substitute 6' for 7' in your example. If the most remote area is the 8' side, now it is 6 heads on the line. If you use your method and take 5 heads per line the minimum length of the design area will not be correct. Tony -----Original Message----- From: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Bob Knight Sent: April 20, 2010 12:30 PM To: sprinklerforum@firesprinkler.org Subject: RE: Calc Area George, The way I do this is to average the lengths between heads. For example, you have a branch line with 6 heads. They are spaced 8', 12', 9', 11', 7', & 10' apart. The average will be 9.5' applying the 1.2 rule (assuming 1500 sf) you will have 4.89 (round up to 5) heads per line. If you use the greatest distance of 12' you end up with only 3.87 (round up to 4) heads per line. If you chose to use the least dimension of 7' you will end up with 6.63 (round up to 7) heads per line. 7 seems like to many and 4 looks like not enough. This is why I average the distance between heads in a case such as yours. Bob Knight, CET 1660 Hill Rd Melba, Idaho 83641 (208) 318-3057 (208) 495-2057 fax b...@firebyknight.com www.firebyknight.com -----Original Message----- From: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of George Medina Jr Sent: Tuesday, April 20, 2010 12:41 AM To: SprinklerFORUM@firesprinkler.org Subject: Calc Area If I am calculating a tree type system using the area/design method, and have several different lengths between sprinklers on a branch line. Would I use the longest length to determine the amount of sprinklers on a branch line. I have always used an average (which I've probably been wrong all these years). 1.2vdesign area S S= Distance between sprinklers on branch line 1.2vdesign area S S= Distance between sprinklers on branch line George Medina Jr. No virus found in this outgoing message. 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