No one in the Pittsburgh Office provided that information, it came from F&EC 1 training in Massachusetts. Still have it in my notes.
Paul J. Pinigis, P.E. Chief Life Safety Engineer -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Joe Hankins Sent: Friday, March 16, 2007 2:26 PM To: [email protected] Subject: Re: Minimum Supply Pressure Paul, While I can't say no one in the Pittsburgh Office told you that, I can tell you that it did not come from any data that FM had then or has now. I know because I tried to squeeze some conclusion like that out of the loss data base, but couldn't do it and still maintain any semblance of statistical rigor. Joe Paul Pinigis wrote: >Those statistics were given to me by Factory Mutual when I worked for >their Pittsburgh office. I have never heard the one about no >multi-death fires in sprinkered buildings, so I can't help you there. > >Paul J. Pinigis, P.E. >Chief Life Safety Engineer > >-----Original Message----- >From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] On Behalf Of Joe >Hankins >Sent: Friday, March 16, 2007 11:56 AM >To: [email protected] >Subject: Re: Minimum Supply Pressure > >Paul, > >Could you pleas provide the source of your statistics? I've heard them >quoted many, many times, but never found anyone who could point to the >actual data behind them. There is another one going around for years >that says there has never been a multiple-death fire in a sprinklered >building. That one is definitely not true. > >Before we start talking about "overkill" in sprinkler designs we need to > >recognize that some current standards have large safety factors, some >have none, and most have unknown safety factors. > >The idea that there is a huge difference between a 5-sprinkler fire and >a 15- or 30-sprinkler fire seems logical on the surface, but if you know > >how sprinklers operate, you know they operate in rings. The heat that >operates sprinklers spreads in a circle from the fire origin. For >symetrically-spaced sprinkler system where the fire starts centered >among 4 sprinklers, there are 4 sprinklers in the first ring around >ignition, so there is virtually no difference between a 1-sprinkler >fire and a 4-sprinkler fire. If those sprinklers don't control the fire, > >then any (and all) of the 12 sprinklers in the next ring can operate, >meaning that there is very little difference betwen a 5-sprinkler fire >and a 16 sprinkler fire. If you get into the next ring, then the number > >is 36 sprinklers. So, the 1-ring "safety factor" between 4 and 16 >sprinklers is the same as the 1-ring safety factor between 16 and 36 >sprinklers. A 1-ring "safety factor" is not overkill in my book! > >Finally, the "cushion" sometimes applied to a water supply is not a >safety factor. In addition to accounting for seasonal, weekly, daily, >and hourly fluctuations, it is a recognition that water supplies >invariably deteriorate and an attempt to avoid the large cost of >upgrading the system or water supply when it does. I'll agree that >adding a cushion to a fire pump supply dedicated solely to a fire >protection system is not necessary, because the pump supply stays the >same unless there is a problem with the pump, which must be fixed >immediately. > >Joe > >Paul Pinigis wrote: > > > >>My point is that there are already so many factors of safety built into >>the design of a system that one more is overkill upon overkill. 95% of >>fires are controlled with one sprinkler operating, 98% of fires are >>controlled with five or less operating, yet we calculate 1,500 square >>feet (or 3,000 square feet for military projects), them we overestimate >>the friction loss in pipe and fittings, underestimate the water supply, >>them worry about adding an additional cushion. >> >>Please, no "what about the other 2%" comments. >> >>Paul J. Pinigis, P.E. >>Chief Life Safety Engineer >> >>-----Original Message----- >>From: [EMAIL PROTECTED] >>[mailto:[EMAIL PROTECTED] On Behalf Of George >>Church >>Sent: Friday, March 16, 2007 9:56 AM >>To: [email protected] >>Subject: RE: Minimum Supply Pressure >> >>Well, there ARE a few more considerations. >>Was the supply adjusted for lowest tank gradient? >>What confidence level do you have in the accuracy of the test data ? >>What confidence level do you have that NO additional 90's will be >> >> >added? > > >>What is the Owner's tolerance for risk? >> >>NFPA #13 does NOT require a cushion. Good trade practice, flexibility >> >> >of > > >>installation changes, common sense, and protection of your boss's >>retirement >>assets require a cushion of some sort. So may the various AHJs you >> >> >face- > > >>water co, fire and code officials, insurance carrier, etc. >> >>So you could be right and fine with .0001 cushion- but in so doing, you >>may >>find yourself in a box scratching for 2.7 PSi in a .0001 margin when a >>duct >>doesn't go in as planned, some cable bracing is discovered, ANYTHING. >> >>We deal with a water company that applies a .8 coefficient to all >>hydrant >>test. If your test was from a .7 hydrant, the supply is overstated and >>your >>system, upon correction, would be 5 or 6 PSI shy. Or if the tank level >>was >>3' above lowest tank gradient, your system won't work in August. >> >>Or 4 heads could control the fire and everyone smiles. We just don't >>know >>EVERYTHING and we can't look into the future. I have trouble sleeping >>when >>we don't have 10%, and prefer 15 PSI+ on prelims on bid day. We just >>analyzed a new site for a customer wanting to use K25s without a pump- >>would >>you tell him, based on 3.6 PSI cushion and ignorant of bar joist >>spacing, >>that it would? We're proceeding with a pump, and if things turn out >>better >>we can omit it, give him a credit for the pump, take some back with the >>$^ >>of k25's, but at least the money's in the job to start with. >> >>When I was assetless and worked for others, I'd consider installing >> >> >what > > >>you >>have. Now, not without everyone involved knowing it, and not if I was >> >> >on > > >>the >>hook for the pump or larger piping replacement, or dual feed mains, or >>whatever was needed to fix whatever changed and bumped us up. Imagine >>going >>to an owner with a $50,000 adder and explaining it with "we had to add >> >> >a > > >>6" >>90 at the top of the riser." Not a situation I'd look forward to ! >> >>glc >> >>-----Original Message----- >>From: [EMAIL PROTECTED] >>[mailto:[EMAIL PROTECTED] On Behalf Of Paul >>Pinigis >>Sent: Friday, March 16, 2007 9:31 AM >>To: [email protected] >>Subject: RE: Minimum Supply Pressure >> >>If you can achieve 10% without spending your client's money (or your >>own) great, but it is not necessary. >> >>Paul J. Pinigis, P.E. >>Chief Life Safety Engineer >> >>-----Original Message----- >>From: [EMAIL PROTECTED] >>[mailto:[EMAIL PROTECTED] On Behalf Of Brian >>Harris >>Sent: Friday, March 16, 2007 9:29 AM >>To: [email protected] >>Subject: RE: Minimum Supply Pressure >> >>10% is what we go by, based on your numbers your only at around 2% :( >> >> Regards, >> Brian Harris >>First Defense Fire Protection >> Design Engineer >> [EMAIL PROTECTED] >> 704.948.3506 phone >> 704.948.3507 fax >> >> >>-----Original Message----- >>From: [EMAIL PROTECTED] >>[mailto:[EMAIL PROTECTED] On Behalf Of Charles >>Thurston >>Sent: Friday, March 16, 2007 10:19 AM >>To: [email protected] >>Subject: Mininum Supply Pressure >> >>Hello All, >> >>Let me be the one to start things today. >> >>What is the minimum safety pressure allowed ? I have looked in 13 and >>did not find it.... I have a situation where the safety pressure is >>0.913 psi. >> >>Basis is: >>Hose 250 >>Static 67.00 >>Residual 38.00 @ 920.00 >>Available 40.128 @ demand of 882.87 >>Requires 39.215 psi >>Leaving a safety of 0.913 psi >> >> >> >> >> >> > >_______________________________________________ >Sprinklerforum mailing list >[email protected] >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > >_______________________________________________ >Sprinklerforum mailing list >[email protected] >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > > > _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum
