My understanding of backflow performance and the mapping of those curves is that the devices impose more pressure loss at opening than at closing. So that spike at 0 GPM is an accurate reflection of the higher pressure loss that occurs at the initiation of a flow event and it almost always ramps right back down once flow rate gets into the dozens or above 100.
But at zero flow, we've always used the ambient static and my vague recollection is that several years ago I confirmed this either with our local Wilkins rep are their factory in San Luis Obispo. I do know that we have never been corrected by an AHJ or third party consultant so I'm 99.9% sure that this is the accepted best practice. Steve L. -------- Original message -------- From: Dewayne Martinez <[email protected]> Date: 1/11/17 5:41 AM (GMT-08:00) To: [email protected] Subject: Static pressure after backflow preventer Is there really a pressure loss at 0gpm flow for backflow preventers like the curves show? I am trying to figure out my static pressure on a floor level with a fire pump at churn and it needs to be accurate. Thanks, Dewayne Martinez Fire Protection Design Manager TOTAL Mechanical Building Integrity W234 N2830 Paul Rd. Pewaukee, WI 53072 [email protected]<mailto:[email protected]> Ph: 262-522-7110 Cell: 414-406-5208 http://www.total-mechanical.com/ [cid:[email protected]] [cid:[email protected]] [cid:[email protected]] [Top Workplaces 2015] TOTAL Mechanical voted "Top Workplace" for a 4th consecutive year.
_______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
