Generally speaking the 0 flow number is the pressure differential required to get the check valve/spring to open. The actual static pressure a system sees is typically the same or arguably higher as surges above the check back pressure will “lock in” above the check valves inside the backflow anyway. RPZs are the only ones where you’d see a lower pressure after the checks due to the central breaker but even then I think typically you’ll see at least the normal static pressure after the backflow.
Mike Morey 2025 NFSA Top Tech Champion<https://www.linkedin.com/posts/national-fire-sprinkler-association_congratulations-to-our-2025-top-tech-winner-activity-7326725245707431936-_5jg/> • NICET IV<https://credentials.nicet.org/47458792-752e-4926-86fc-bd4d47722218#acc.kBTieRXy> • CFPS<https://www.credly.com/badges/c05de73a-dbed-4c31-b1dc-0be93f3151f0/public_url> Project Estimator • Fire Protection Group Shambaugh & Son, LP an EMCOR Company 7614 Opportunity Drive • Fort Wayne, IN • 46825 direct 260.487.7824 / cell 260.417.0625 email [email protected]<mailto:[email protected]> 24/7<outlook-data-detector://2/> SERVICE LINE 888.217.7055<tel:888.217.7055> [cid:[email protected]] From: Matt Grise <[email protected]> Sent: Thursday, August 13, 2026 8:43 AM To: Discussion list on issues relating to automatic fire sprinklers <[email protected]> Subject: [Sprinklerforum] static pressure loss through backflow do backflow preventers typically reduce static pressure? The charts provided with BFP's do show a loss at 0gpm, but is loss the same when flow is increasing and decreasing? I usually apply the pressure loss from a BFP at a flowing condition, ZjQcmQRYFpfptBannerStart This Message Is From an Untrusted Sender You have not previously corresponded with this sender. ZjQcmQRYFpfptBannerEnd do backflow preventers typically reduce static pressure? The charts provided with BFP's do show a loss at 0gpm, but is loss the same when flow is increasing and decreasing? I usually apply the pressure loss from a BFP at a flowing condition, so I'm not sure how they affect static condition. Anyone know? Thanks! Matt Grise This message is for the named person's use only. It may contain confidential, proprietary or legally privileged information. No confidentiality or privilege is waived or lost by any mistransmission. If you receive this message in error, please immediately delete it and all copies of it from your system, destroy any hard copies of it and notify the sender. You must not, directly or indirectly, use, disclose, distribute, print, or copy any part of this message if you are not the intended recipient.
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