I don't like it Bill, due to the embarrassment that occurs between 19 and 21 feet :)
-----Original Message----- From: Bill Brooks [mailto:bill.bro...@brooksfpe.com] Sent: Monday, June 04, 2012 8:04 AM To: sprinklerforum@firesprinkler.org Subject: RE: minimum 7 PSI end head logic, check please! What are you comments with regard to Figure 11.2.3.2.3.1 (2010)? Bill Brooks -----Original Message----- From: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Brad Casterline Sent: Monday, June 04, 2012 8:49 AM To: sprinklerforum@firesprinkler.org Subject: RE: minimum 7 PSI end head logic, check please! Thanks Mark, I would not want to reduce LH spacing. I think density should be tied to sprinkler height and area to occupancy. I think the water demands are too high for low ceilings and too low for high ceilings. Basing min flow rate on density time head area, without min end head PSI brings the demand down where the ceiling heights are less that 12'-6". Activation time is a function of ceiling height and is the main reason for tieing density to it too. thanks again, Brad -----Original Message----- From: mphe...@aerofire.com [mailto:mphe...@aerofire.com] Sent: Monday, June 04, 2012 7:30 AM To: sprinklerforum@firesprinkler.org Subject: Re: minimum 7 PSI end head logic, check please! Research the development history of the Residential sprinkler. It was done during the late 70's and covered all the issues you're thinking about here. I believe NFPA 13D was first published in 1980 or '81. I think I remember that some of the first heads listed for "residential" had a minimum starting pressure of 5 PSI. I know there were design densities of .05 GPM/PSF. Also the residential Sprinkler is designed to hit the WALL near the ceiling at minimum operating pressure. Just out of curiosity, why would you want to reduce LH spacing to 100 Sf? Mark at Aero ----- Original Message ----- From: Brad Casterline [mailto:bcasterl...@fsc-inc.com] Sent: Monday, June 04, 2012 06:57 AM To: sprinklerforum@firesprinkler.org <sprinklerforum@firesprinkler.org> Subject: RE: minimum 7 PSI end head logic, check please! Good points guys, thanks. Here is an 'equivalency thought experiment' if the Forum will suffer me a little more: the water hits the floor (at a wall 9' away when it has 7 PSI on it. Throttle the flow down until it hits the floor 5' away. Now what is the pressure? We don't know until we measure it, but for 100 s.f. head spacing it is obviously less than 7 PSI. I am not trying to rock the boat or waste anyone's time. I plan on submitting a proposal for change regarding calc rules for water supplies for LH and OH, so I am trying to establish equivalency, identify arbitrariness, etc. Is it coincidence that 7 PSI is 32 ft/sec? I only got 20 years to get this change through so I thought I'd better get started. -----Original Message----- From: Ron Greenman [mailto:rongreen...@gmail.com] Sent: Sunday, June 03, 2012 3:57 PM To: sprinklerforum@firesprinkler.org Subject: Re: minimum 7 PSI end head logic, check please! Oops, forgot the pattern part (thanks Bruce), but the argument is the same. The head is tested/listed at not less than psi. Rule 1 then is 7 psi or more, if less than 7 psi raise the starting pressure to 7 psi, that's it, don't worry, carry on, complete the design, get it out the door, and approved, build-it, get it signed off, collect the money, move on. On Sun, Jun 3, 2012 at 1:36 PM, Bruce Verhei <bver...@comcast.net> wrote: > Would the heads make an effective pattern below 7psi, and more > important, is the answer known, and not guessed at? > > Bruce > > Sent from my Motorola ATRIXT 4G on AT&T > > -----Original message----- > From: bcasterl...@fsc-inc.com > To: sprinklerforum@firesprinkler.org > Sent: Sun, Jun 3, 2012 20:31:30 GMT+00:00 > Subject: minimum 7 PSI end head logic, check please! > > Fact: a minimum pressure is required to 'push the stopper out of the > orifice' once the 'link has broken'. This means the column of water > above the head has to be at least 16 feet tall. (i wonder if this is > enough for the 'bigger stoppers' of today, but I'll trust the > manufacturers). An overall statement could be made "Sprinklers do not > work where the static is > less than 7 PSI". > Question: Why should we calculate the minimum required flow rate based > on anything other than density times head area, since at that point > the stopper has already been pushed out? > If in doubt about the Pt available to a non-flowing head when others > are flowing, couldn't we use a flow test graph to find GPM at 7 PSI, > and make sure we are flowing less than that? > > _______________________________________________ > Sprinklerforum mailing list > Sprinklerforum@firesprinkler.org > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > -------------- next part -------------- An HTML attachment was > scrubbed... > URL: < > http://fireball.firesprinkler.org/mailman/private/sprinklerforum/attachments /20120603/c7182724/attachment.html > > > _______________________________________________ > Sprinklerforum mailing list > Sprinklerforum@firesprinkler.org > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > -- Ron Greenman Instructor Fire Protection Engineering Technology Bates Technical College 1101 So. Yakima Ave. Tacoma, WA 98405 rgreen...@bates.ctc.edu http://www.bates.ctc.edu/fireprotection/ 253.680.7346 253.576.9700 (cell) Member: ASEE, SFPE, ASCET, NFPA, AFSA, NFSA, AFAA, NIBS, WSAFM, WFC, WFSC They are happy men whose natures sort with their vocations. -Francis Bacon, essayist, philosopher, and statesman (1561-1626) -------------- next part -------------- An HTML attachment was scrubbed... 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