Backflows do have a psi drop at no flow conditions. That psid will vary based on the spring strength on the clapper and other conditions. Backflow certification requirements require at least 1 psid per check valve for a double check and more for an RPZ. To be specific on the exact psid for your device you would need to test it. If the device isn't installed, all you can do is use the manufacturers supplied literature.
B.J. Newlin Service Manager Aegis Fire Protection LLC. “Whoever is careless with the truth in small matters cannot be trusted with important matters” ― Albert Einstein From: Sprinklerforum [mailto:[email protected]] On Behalf Of Matt Grise Sent: Wednesday, January 11, 2017 8:03 AM To: [email protected] Subject: RE: Static pressure after backflow preventer Might be worth a call to the manufacturer. Matt Grisé PE*, LEED AP, NICET II Vice President – New Construction Alliance Fire Protection 130 w 9th Ave. North Kansas City, MO 64116 *Licensed in KS & MO 913.888.0647 ph 913.888.0618 f 913.526.7443 cell www. AFPsprink.com From: Sprinklerforum [mailto:[email protected]] On Behalf Of [email protected] Sent: Wednesday, January 11, 2017 7:57 AM To: [email protected] Subject: RE: Static pressure after backflow preventer Seems logical for a RPZ type backflow preventer. J. Scott Mitchell, PE Senior Fire Protection Engineer Mission Engineering CNS Y-12 | 865-576-5258 CNS PTX | 806-477-5883 From: Sprinklerforum [mailto:[email protected]] On Behalf Of Dewayne Martinez Sent: Wednesday, January 11, 2017 8:40 AM 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] 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. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
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