That is a relatively recent change in the good old days that I've never really heard definitive answers on when the 3/4" went away and when staggered changed. Before my time, I only go back to the end of 3.5" and 5", scheduled systems, threaded fittings and 2' away start the grooved couplings, and water motor gongs.
I remember thinking I was following a 669 fitter in a parking lot since his license plate was WMAG 300 Water Motor Alarm Gong, 300 machine, right? What else could it be? Uh, Winchester magnum 300 was the rather confused answer I got. Oh, yeah, I guess it could be that, too. Guess its obvious I don't hunt. George L. Church, Jr., CET Rowe Sprinkler Systems, Inc. PO Box 407, Middleburg, PA 17842 877-324-ROWE 570-837-6335 fax [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of David deVries Sent: Thursday, April 26, 2012 5:04 PM To: [email protected] Subject: Re: Rounding off {Squaring off?} Don't know if there is a connection without researching it, but it seems that staggered sprinklers went out about the same time as standard spray sprinklers replaced old style sprinklers and their narrower distribution pattern. Dave On Thursday, April 26, 2012, wrote: > > > In the "old days" heads were staggered to help even out the flow as > well as hasten the acttivation. > > > > David Bohannon > > > > Fire Sprinkler Plan Review City of Atlanta > > > > Department of Planning and Community Development > > > > Office of Buildings > > > > 55 Trinity Avenue > > > > Suite 3900 > > > > Atlanta, GA 30303 > > > > e-mail: [email protected] <javascript:;> > > > > phone: 404-330-6193 > > > > fax: 404-739-4172 > > > > > > > > ----- Original Message ----- > > > From: "Mark Sornsin" <[email protected] <javascript:;>> > To: [email protected] <javascript:;> > Sent: Wednesday, April 25, 2012 4:18:18 PM > Subject: RE: Rounding off {Squaring off?} > > I think it ultimately goes to the fact that they needed a simple way > to space sprinklers and square is much easier to work with than round. > > As to the safety factor, Bruce pretty much hit it: it works. What is > implied is that whatever the safety factor is it must be enough. The > problem is, if you try to analyze the actual factor of safety you have > to first ignore several other potential influences on that factor. > Accuracy of the water supply information; actual pressure at the > sprinkler; choice in design area (which may be affecting the actual > pressure on the sprinklers); effect on calculations of including hose > allowances and/or domestic allowances; effect on calculations of using > assumed (vs actual) friction coefficients for the pipes; etc. When > some people make the point that sprinkler calculations have 'so much' > safety factor built into them they are essentially correct. But why do > people make those assertions? Usually it is to justify lack of > conformity to standards; and the problem with going down that road is > that none of these above influences can be precisely measured in terms > of additional safety factor they may or may not be providing. True, > some jurisdictions will waive hose allowances in calculations under > limited circumstances if it means saving the added cost of a pump > and/or tank. Certainly the knowledge of the remaining potential > factors of safety is a reason for doing this (on a limited basis). But > you don't want to push it any farther than disregarding one fairly measurable > variable because uncertainty raises exponentially with each added variable. > > So the bottom line in my view is that one could certainly do a > mathematical exercise where they calculate the safety factor of all of > the overlap in sprinkler sprays; but first they would have to make > assumptions about those other influences. By the time they are done > doing that, the exercise is nearly worthless, except as a bit of > intrigue for those of us in the business. > > BTW - you can go to some manufacturer's web sites and view sprinkler > spray patters. If you look at the Viking M 1/2 in. upright, you'll see > that at 7psi, the spray from about 8 ft. above the floor reaches just over 9 > ft. > from the centerline of the sprinkler. In a Light Hazard Occupancy, > that overlaps the 7'-6" maximum distance, but does not reach the > maximum diagonal distance of 10.6 ft. At 30 psi, you get closer to the 10.6 > ft. > Obviously, at smaller spacing, the overlap increases (another variable > to consider). > > Mark A. Sornsin, PE| Fire Protection Engineer Ulteig Engineers, Inc.| > Fargo, ND [email protected] > > > -----Original Message----- > From: [email protected] [mailto: > [email protected]] On Behalf Of Bruce Verhei > Sent: Tuesday, April 24, 2012 12:51 PM > To: [email protected] > Subject: Re: Rounding off {Squaring off?} > > I've read in the past that this fell in the not well understood effect > category when engineers have desired to model how sprinklers actually work. > This seems to be difficult. They say something that ends with but > sprinklers installed and maintained to standards have a remarkable > record of controlling fires in buildings. > > I want to buy one of the square heads. Are the threads square too? > > Bruce > > Sent from my Motorola ATRIXT 4G on AT&T > > -----Original message----- > From: Thomas Watt <[email protected]> > To: [email protected] > Sent: Tue, Apr 24, 2012 13:05:01 GMT+00:00 > Subject: Rounding off {Squaring off?} > > I had a brain-fart and came up with this question for the forum. > Especially the engineers. Since sprinklers, in general, throw in a > circular pattern, and we calc the sprinklers as squares, there is > always overlap so we are by default miscalculating a percentage of the > density. > Has anyone ever calculated the safety factor effect by ignoring the > arcs outside the square??? > > Thomas > A+ fitter/Foreman > No work in Orlando, FL area > Willing to relocate > -------------- next part -------------- An HTML attachment was > scrubbed... > URL: < > http://fireball.firesprinkler.org/mailman/private/sprinklerforum/attac > hments/20120424/5639c5b1/attachment.html > > > ________________________URL: < > http://fireball.firesprinkler.org/mailman/private/sprinklerforum/attac > hments/20120426/f2dde620/attachment.html > > > _______________________________________________ > Sprinklerforum mailing list > [email protected] <javascript:;> > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > -------------- next part -------------- An HTML attachment was scrubbed... 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