For the record, I have only designed one system with a pressure cushion of less than 5 psi, and that was where the client arbitrarily decided that we needed to double the design area..."if 1,500 square feet is enough for everyone else, we want at least 3,000." Go figure.
Paul J. Pinigis, P.E. Chief Life Safety Engineer -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chris Cahill Sent: Friday, March 16, 2007 11:34 AM To: [email protected] Subject: RE: Minimum Supply Pressure In defense of Paul, he was not disagreeing with the original thread but very accurately pointing out a fire marshal cannot legally require any more than the code (law). He (and I last week) are talking about the resignation many seem to have the AHJ is always right or at least you follow their direction. Now George points out he has some fire marshals that have legally modified the standard thus making something more restrictive the new minimum in at least that jurisdiction. No one is complaining about these legal modifications. It's the non-legal ones sometimes called policies. I'll also defend Paul's other comments about built in safeties. He never said 0.913 is OK. Nor did he suggest the building would get built to plan. He was just pointing out what Ron summed up another way: "> Yet another case of calculate with a computer, measure with a > micrometer, mark with a piece of chalk and chop off with an axe. > Ron Fletcher" Oh, and I don't know Paul, have never received and compensation from him for any reason. Fully .913 is OK with NFPA 13 IF the flow test is accurate and accounts for reasonable fluctuations AND the system isn't modified AND a few other caveats. But none of this means we should design for 0.000 "safety". And I say "safety" because this is on top of all the other safeties and is only a part of the real safety. We should (but don't have to by law) consider what could change or go wrong and pad the issue to protect in order of importance the life of occupants (including FF), the valuable of occupant's possessions and your corporate assets. It's fully reasonable for the AHJ after installation to reject a system with a .913 safety because a line was shifted or whatever. Does anyone want to reasonable argue on the day of a fire if the supply pressure is a few PSI under the calculated PSI it's going to make a difference in the outcome of the fire. If so I suggest you get a copy of NFPA's report on sprinkler operations that basically says if the valve is open things will be OK. That may be simplifying it a bit but that's what I come away with. Systems fail because there is no supply, or high piled storage with a light hazard design or other gross problems. A few PSI here or there will not make a difference in 99.9999% of the cases. And the .0001%, well we have bigger issues to resolve. You may not believe it but I had someone ask if a sprinkler company could be held liable for over designing because of too much water damage. I think they were trying for if 15 gpm would put out the fire then they were liable for the extra 30 gpm that actually came out. But I wouldn't entertain the conversation long enough for such IMHO foolish ideas, lawyers! Chris Cahill, P.E. Fire Protection Engineer Sentry Fire Protection, Inc. 763-658-4483 763-658-4921 fax Email: [EMAIL PROTECTED] Mail: P.O. Box 69 Waverly, MN 55390 Location: 4439 Hwy 12 SW Waverly, MN 55390 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Kathryn Tyler Sent: Friday, March 16, 2007 9:42 AM To: [email protected] Subject: RE: Minimum Supply Pressure Paul and Chief Life Safety Engineer, Maybe you have not designed jobs to actually be installed in the field, but chances are the building will not get built exactly as the plans indicate, the HVAC will not get installed exactly as the plans indicate and so on... AND THE FIRE PROTECTION MAY NOT GET INSTALLED EXACTLY AS IT IS DRAWN, which means the fitters may have to add a few 90's, etc. and that is way a safety margin of 10% is not only a good practice, but possibly to make sure of changes in the field will still allow the system to function properly and put out a fire if needed. Kathryn -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Pinigis Sent: Friday, March 16, 2007 7:14 AM To: [email protected] Subject: RE: Minimum Supply Pressure We have an AHJ who has developed a "god complex" from years of having contractors, engineers, and building owners bow down to kiss his feet and satisfy his every whim. It is now at the point that he believes that it is his prerogative to choose the construction type of the building, the type of smoke detection system that is used, the manufacturer of the fire alarm system, etc.! The AHJ is there to enforce the code, not to reinvent it. Paul J. Pinigis, P.E. Chief Life Safety Engineer -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Friday, March 16, 2007 10:05 AM To: [email protected] Subject: RE: Minimum Supply Pressure I know the municipal AHJ issue has been discussed before. When the AHJ asks for something and denies a C.O. based on your refusal to provide what was asked, it's often easier to comply if it's not a liability or cost issue. Most owners don't appreciate a delay in occupying their facilities based on the legality of what the AHJ can or cant legally ask for. Sure we would like to push back and fight it, but the reality is sometimes that's not practical or feasible. The owner may never see you again after your job is done but he'll probably see that fire marshal every year. Also the term AHJ can also apply to a corporate life safety manager or other corporate entity for companies who are self-insured and self sufficient, i.e. no interface with local municipalities, they have their own private water supplies, private fire brigades, etc. Craig L. Prahl, CET Fire Protection Group Mechanical Department CH2MHILL Lockwood Greene 1500 International Drive PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 [EMAIL PROTECTED] http://www.lg.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Pinigis Sent: Friday, March 16, 2007 9:54 AM To: [email protected] Subject: RE: Minimum Supply Pressure Yes, the insurance underwriters can add their requirements, but the AHJ cannot. The AHJ is tasked with enforcing the adopted codes, not inventing new ones or adding his/her personal preferences. The code does not demand a pressure cushion, neither can the AHJ. Paul J. Pinigis, P.E. Chief Life Safety Engineer -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Friday, March 16, 2007 9:41 AM To: [email protected] Subject: RE: Minimum Supply Pressure Also, some insurance underwriters and AHJ's have requirements relating to particular required safety factors in the calcs. Don't forget to check with them as well. Craig L. Prahl, CET Fire Protection Group Mechanical Department CH2MHILL Lockwood Greene 1500 International Drive PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 [EMAIL PROTECTED] http://www.lg.com -----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 -- Best regards, Charles mailto:[EMAIL PROTECTED] Coastal Fire Protection _______________________________________________ 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 _______________________________________________ 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 _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum
