One thing that can happen is pulling a vacuum on private systems attached to the main. I don't recall the exact details, but I think it was in Standish, MI in about 1994 that a hurry-up pump test was pushed at a retail center for a Home Depot store in order to get ready for a soft opening. In spite of the fact that the water purveyor had not yet finished an upgrade to the main that would be feeding this property and its two or three big-box anchors. So when the pump test went toward or into overflow condition, sprinklers and regulators an irrigation system across the street from the subject property imploded and there was some other damage about which I can't recall details.
If the water supply from which a pump is taking suction is subject to fluctuations that could put it below the demand (calculated or however you arrive at that datum) then either a break tank or low suction throttling device would be an appropriate accessory. Steve Leyton -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of ParsleyConsulting Sent: Wednesday, November 17, 2010 12:21 PM To: [email protected] Subject: Re: Fire Pump's Brad, I'd like to ask about your comment: "good sense to waive off sprinkler calcs as meaningless." Can you help me understand what you're referring to here? I thought the concern was valid. The FM appeared to be asking a legitimate question, such as "what happens if the flow at 150% of rated capacity draws my municipal main down below 20 psi?" The 2010 edition of NFPA-20 addressed this in the sections I quoted Brian. I wasn't there for those ROP/ROC meetings, but the new material was voted in almost unanimously. Reading that new language in NFPA-20, it also brought up a point I hadn't considered - isn't there a requirement to test the fire pump to that 150% capacity? I thought NFPA-25 called for that in the annual flow testing in 8.3.3.1. If the municipal main can't supply the water to meet that 150% figure I'd ask the same questions, I think. Perhaps a different way than happened for Brian, but I'd ask. Are you suggesting that such information is irrelevant? PARSLEY CONSULTING Ken Wagoner, SET 760.745.6181 voice 760.745.0537 fax [email protected] <mailto:[email protected]>e-mail www.ParsleyConsulting.com <http://www.ParsleyConsulting.com>website On 11/17/2010 11:29 AM, Brad Casterline wrote: > This FM's problem is > that he/she has the good sense to waive off sprinkler calcs as meaningless. > _______________________________________________ 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) _______________________________________________ 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)
