Thanks, your procedure and concepts sound fine-- (except "...the size of remote area..." should be ... the minimum length...). What is being wondered about is simply semantics-- does the word USED from 'calculation procedure' mean the same thing as the equivalent of SELECTED from 'design approaches', Or does it mean the final size of the area calculated. The reason we have to stretch the area parallel to the branch lines is bcoz 5 heads flowing on 3 lines is more demanding than 3 heads flowing on 5 lines. I have heard that when calcs were first being done, the calc areas were round, like most fires.
-----Original Message----- From: Michael J. Ricks [mailto:m...@fire-sprinkler-design.com] Sent: Wednesday, April 21, 2010 12:29 PM To: sprinklerforum@firesprinkler.org; bcasterl...@fsc-inc.com Subject: RE: Calc Area If this has already been talked about I apologize. The important thing to remember is that, as mentioned below, the size of remote area must be at least 1.2 times the square root of the design area measured along the branch line. The method to determine that as described in NFPA 13 A14.4.4 (2002 edition) only works if the heads are evenly spaced and exactly 1/2 the allowable distance from the wall. The same is true when you are determining the total number of heads in your design area. When determining the total number of sprinklers in the design area and along the branch line, the proper geometric area for system design, which is selected from the curves in NFPA 13, must be verified. I find it easiest to take the head I think is the most remote and from the point it sprays to (usually a wall or if on a grid or end of a multiple system building, half way to the next head) and draw a line from that point perpendicular to the branch line 1.2 times the square root of the design area (46.5 feet if using a 1500 sq. ft. area). All the heads on the remote head side of the line needs to be in my design area and if that line is more than half way between the last head and the next head on the branch line, you need to go to the next head after that. The bottom line is that despite what A14.4.4 says, the actual design area must be 1) at least as large as the area selected from the curve and 2) the length of the design area as measured along the branch line must be at least 1.2 times the square root of that area. I find that A14.4.4.4 has very little practical application in the real world. What you need to look out for when determining your design area is when heads are not symmetrically spaced, the most demanding area may not be the most remote. For example, if at the end of a branch line your heads are space at 15 feet, but closer to the source, your heads are spaced at an average 8 feet, you would need to prove 6 heads where you have 8 foot spacing and only 4 with the 15 foot spacing. In some cases you may need to provide a proof calc for both areas to determine which area is actually the most demanding. Michael Ricks Katco Fire Sprinkler Design P.O. Box 607 555 South 100 East Salem, UT 84653 801-423-3096 Cell: 801-380-4651 -----Original Message----- From: Brad [mailto:bcasterl...@fsc-inc.com] Sent: Tuesday, April 20, 2010 3:30 PM To: sprinklerforum@firesprinkler.org; bcasterl...@fsc-inc.com Subject: RE: Calc Area I will have to wait til tomorrow for any replies-- I am 3 years in to recovery from Internet At Home, and am going there now---- -----Original Message----- From: Brad [mailto:bcasterl...@fsc-inc.com] Sent: Tuesday, April 20, 2010 4:23 PM To: sprinklerforum@firesprinkler.org Subject: RE: Calc Area So, Cecil, should I feel bad about leaving a box or 2 of heads off remote lines or not? -----Original Message----- From: George Church [mailto:for...@ptd.net] Sent: Tuesday, April 20, 2010 4:12 PM To: sprinklerforum@firesprinkler.org Subject: RE: Calc Area Y'all REALLY REALLY need to sign up for one of Cecil's online classes if we spend this much time talking about how we lay out the MRA. If you're unsure, or the code changed and you didn't, maybe it's time to go back to school. No shame in making sure you do it correctly from this crowd! And ya know the inspector and plan reviewer aren't gonna catch these things 98% of the time. So you'll either "get away" with a mistake, or you'll be defending your methodology in court, with your design guru(s) sitting beside you, facing the best forensic engineering talent money can buy. Remember, they may be looking to pin a couple to several million dollar loss on YOU and your insurance carrier. And if you carry $2m in coverage, have a $3m loss, guess what happens to your house, business, car, etc? If you've still got assets to protect, I'd be careful to do it correctly. That MINIMUM consensus standard isn't the end all, be all. It's a MINIMUM standard. glc -----Original Message----- From: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Brad Sent: Tuesday, April 20, 2010 3:44 PM To: sprinklerforum@firesprinkler.org Subject: RE: Calc Area I was shocked when first confronted with the idea 8 years ago--- let us see what others have to say... -----Original Message----- From: ParsleyConsulting [mailto:parsleyconsult...@cox.net] Sent: Tuesday, April 20, 2010 2:35 PM To: sprinklerforum@firesprinkler.org Subject: Re: Calc Area Brad, I was intrigued by your remarks about having to re-evaluate the minimum length of the remote area parallel to the branch lines if you were to end up with a remote area of a different size than where the standard initially had you start. I can't find anything in my copy of the NFPA-13 handbook, or the Hydaulic Design text book by Pat Brock from Oklahoma State which even remotely suggests this is a requirement. I've never done this, and I want to be sure I haven't missed something critical. I need to be sure I understand what you're saying, because for me the implications are huge for the plans I review on a daily basis for a number of AHJ's. Are you stating that if in order to meet the requirements for a 1,500 square foot remote area I were to end up with a remote area of 1,600 square feet I then have to make an evaluation to make sure that the length of the remote area parallel to the branch lines is at least 1.2 x sqrt of 1,600? In effect, I need at least 48'-0", not the 46'-5" I started with? If that's your position, can you give me some idea of how you determined that such an additional requirement is necessary? I've got to tell you that if that is truly the case, I'm in seriously deep trouble, as I've been doing calculations and plan reviews based on a flawed premise, and that makes me really nervous. Can you give me/us some background on how you came to that conclusion? I'd really appreciate the help. -- PARSLEY CONSULTING Ken Wagoner, SET 760.745.6181 voice 760.745.0537 fax parsleyconsult...@cox.net <mailto:parsleyconsult...@cox.net> e-mail www.ParsleyConsulting.com <http://www.ParsleyConsulting.com> website Brad wrote: > I don't think this is about density at all > > > -----Original Message----- > From: A.P.Silva [mailto:silva...@shaw.ca] > Sent: Tuesday, April 20, 2010 2:13 PM > To: sprinklerforum@firesprinkler.org; bcasterl...@fsc-inc.com > Subject: RE: Calc Area > > If I understand what you are saying, it may not be correct either. If you > use the density corresponding to 1500 SF, then you don't have to check the > length again. If you use the density for 1640 SF, then you are right. > > Tony > > -----Original Message----- > From: sprinklerforum-boun...@firesprinkler.org > [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Brad > Sent: April 20, 2010 1:02 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. > Checked by AVG - www.avg.com > Version: 9.0.801 / Virus Database: 271.1.1/2820 - Release Date: 04/19/10 > 00:31:00 > > _______________________________________________ > Sprinklerforum mailing list > Sprinklerforum@firesprinkler.org > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > For Technical Assistance, send an email to: supp...@firesprinkler.org > > To Unsubscribe, send an email to:sprinklerforum-requ...@firesprinkler.org > (Put the word unsubscribe in the subject field) > > _______________________________________________ > Sprinklerforum mailing list > Sprinklerforum@firesprinkler.org > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > For Technical Assistance, send an email to: supp...@firesprinkler.org > > To Unsubscribe, send an email to:sprinklerforum-requ...@firesprinkler.org > (Put the word unsubscribe in the subject field) > > _______________________________________________ > Sprinklerforum mailing list > Sprinklerforum@firesprinkler.org > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > For Technical Assistance, send an email to: supp...@firesprinkler.org > > To Unsubscribe, send an email to:sprinklerforum-requ...@firesprinkler.org > (Put the word unsubscribe in the subject field) > > _______________________________________________ > Sprinklerforum mailing list > Sprinklerforum@firesprinkler.org > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > For Technical Assistance, send an email to: supp...@firesprinkler.org > > To Unsubscribe, send an email to:sprinklerforum-requ...@firesprinkler.org > (Put the word unsubscribe in the subject field) > > _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: supp...@firesprinkler.org To Unsubscribe, send an email to:sprinklerforum-requ...@firesprinkler.org (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: supp...@firesprinkler.org To Unsubscribe, send an email to:sprinklerforum-requ...@firesprinkler.org (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: supp...@firesprinkler.org To Unsubscribe, send an email to:sprinklerforum-requ...@firesprinkler.org (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: supp...@firesprinkler.org To Unsubscribe, send an email to:sprinklerforum-requ...@firesprinkler.org (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: supp...@firesprinkler.org To Unsubscribe, send an email to:sprinklerforum-requ...@firesprinkler.org (Put the word unsubscribe in the subject field)
