Agree, but consider this please: 3 heads, 5 feet apart, middle one pops-- the other two are very close to activation also being that near-by, and will likely activate while the 1st one is still coughing up air. To feel comfortable with the semantics, 13 talks about special sprinklers and situations, in 3 and 8 I think.
-----Original Message----- From: Cahill, Christopher [mailto:[email protected]] Sent: Wednesday, May 15, 2013 8:09 AM To: [email protected] Subject: RE: baffles You are forgetting about the actual droplet hitting the unfused head. That is the reason there are minimum spacing requirements. It takes some time even in the hottest part of the plume to transfer a droplet to steam. The time it takes to evaporate the water is dependent on the initial droplet size. We are rightfully moving in a direction of encouraging larger droplets (more so storage). It doesn't take a lot of not quite vaporized droplets hitting the unfused heads to keep them from fusing. Yes, in a theoretically large fire, eventually the unfused head does operate. But if we are waiting for it to grow to theoretically large we probably better call our insurance company to get the investigators to the black hole while the evidence is fresh. And ponder this. Last time I read the UL testing they tested at 6' apart and the same elevation at 100 psi. But in real life adjacent heads could be 11" vertical and almost 175 psi. Makes me think there could be some issues in some probably rare circumstances. I looked into this once when I saw the heads running along the BL two up, one down due to where they landed in the trusses. Granted the pipe of the one down does offer some protection but made me think anyway. Chris Cahill, PE* Senior Fire Protection Engineer, Aviation & Facilities Group Burns & McDonnell 8201 Norman Center Drive Bloomington, MN 55437 Phone: 952.656.3652 Fax: 952.229.2923 [email protected] www.burnsmcd.com Proud to be one of FORTUNE's 100 Best Companies to Work For *Registered in: MN -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Brad Casterline Sent: Wednesday, May 15, 2013 7:47 AM To: [email protected] Subject: RE: baffles I would argue baffles not required. It is a special situation any time you can't get 6' min, probably using 'Special Sprinklers'. I believe 6' is the generic situation. Since they are already there, uhhh... I'm looking at an exit sign right now with heads on both sides of it. Any time a head operates the nearby heads are cooled by water vapor in the ceiling jet. If the fire in these special situations is not controlled by one head, it will 'un-solder' the one a few feet away, seems to me. We should put the cost toward avoiding obstructions to the pattern, not fabricating approved ones! -----Original Message----- From: AKS-Gmail-IMAP [mailto:[email protected]] Sent: Tuesday, May 14, 2013 10:25 PM To: [email protected] Subject: Re: baffles The baffle is supposed to be able to stay in place. First compare the softening temerature point for the plastic and the sprinkler temperature rating. The more expensive plastics soften at a temperatures way above typical sprinkler temperatures. Even if the plastic is not melting away it may have lost enough strength so that it no longer functions as a baffle at first blast, where upon it will become rigid again in a deformed state if it is still there. That is the nature of a plastic. This takes you to the next item. How the baffle is held in place influences how well the baffle will stay in place in its greatly temperature reduced strength state. In case you are thinking glass, the problem with glass is that it needs to survive a temperature change shock and may itself drop out of its holder onto people below. You cannot drill bolt holes in some heat resistant glass. So you are pretty much stuck with plastic if you want it clear. Get a candy thermometer and heat up water i n a large cooking pot to 150 F or so. Put the baffle in there and leave it for a long enough time so that it has become as soft as it will get. That might be 8 minutes or more at least. Pull it out and use some vise grips gripping it in the way it will be attached to see how soft it really is. That test should tell you a lot. Let us know what you find out. By the way, and it is probably too late now, only the more expensive hard plastics, like what might be used in a hockey rink, will not be scratched so easily from the wiping down cleaning it might get. Allan Seidel St. Louis, MO On May 13, 2013, at 11:56 PM, A.P.Silva <[email protected]> wrote: > NFPA 13 requires baffles (between sprinklers) to be non-combustible or > limited-combustible. The contractor has installed plexi-glass baffles, > and claims that is what is normally used and has been approved on > previous projects. > > Any comments? > > Tony > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
