No argument on that philosophy but when one gets there and uses that as the jumping off point to require a more restrictive standard based on a feeling that a cushion would be better and then picking an arbitrary number for that cushion based on nothing then you've moved away from the realm of past practice (experience), empirical data, and real science for no more reason than the "what if" mind game. You (not you particularly David but the big generic you out there) might as well require the throwing of bones and the conjuring of spells because you have moved into the realm of superstition and magic. Cargo cultists of the Pacific just didn't put up enough bamboo pools or light enough signal fires to get the magic "stuff" birds to come back. Even if I think cushions are a good idea in lieu of other measures I will continue to rant in rave about arbitrary rules imposed by local "officials" and defended as being necessary because of special conditions when those conditions aren't enumerated nor supported by any data other than "because I'm the AHJ." Neither I nor any local AHJ has the tools to determine that the adequate water supply of today is not going to be adequate tomorrow or that if it should become less than now that a 5% or 10% or 10 psi cushion will be adequate. We cannot design to what might happen in those things out of our control like the indoor soccer arena that secretly becomes a high-piled methylethyldeath warehouse or a combustionium manufactory. We can design to a prescription that has been established with great debate by a group of recognized experts with special and collective interests debating openly based on pertinent data as it applies statistically to past performance (mixed with a pinch science, a dash of testing and a heaping tablespoon of ego) to arrive at a standard that provides for a reasonable degree of safety under prevailing and reasonably anticipated conditions. Now we just finished hearing tales of deteriorated systems that occurred before the building was finished to improved conditions that caused a pump to over pressure a system. A cushion is not a cure for any of this. It may be a band aid or aspirin under certain conditions but not a cure. A tank on every system is the cure to a dependable and stable water supply. Shall we go there? Should NFPA mandate a cushion? What should it be? Is 5% reasonable? Does this provide a sufficient cure to this apparently overwhelming problem (although I've never seen anything to support this need for a cushion being based on anything more than random anecdotes) without unnecessarily requiring untold numbers of building owners to pay more for systems than would otherwise be necessary if a random and capricious requirement were not imposed. I think we're treading into the realm of risk management guided by necromancers.
On Thu, Sep 24, 2009 at 1:37 PM, Autry, David <[email protected]> wrote: > I'll add a closing note as well. > When I see a system calculated to the curve, I tend to check the calculations > a lot closer for correct pipe lengths, number of fittings, valves, etc..... > > > David Autry > Plans Examiner > Nebraska State Fire Marshal's Office > 246 S. 14th Street > Lincoln, NE 68508 > 402-471-9659 > 402-471-3118 fax > www.sfm.ne.gov > > ** Note new email address: [email protected] > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > For Technical Assistance, send an email to: [email protected] > > To Unsubscribe, send an email to:[email protected] > (Put the word unsubscribe in the subject field) > -- Ron Greenman Instructor Fire Protection Engineering Bates Technical College Tacoma, WA Member: SFPE, ASCET, NFPA, AFSA, NFSA AFAA, WSAFM _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
