Have you looked in the 2022 or 2025 edition to see if the wording changed? Todd Williams
Fire Protection Design/Consulting Stonington, CT 860-608-4559 > > On Sep 24, 2026 at 10:45 AM, <Joe Burtell [MT-BILL] > (mailto:[email protected])> wrote: > > > > I've got a combined sprinkler/standpipe system I'm working through and want > to bounce a question off you, since you're on the NFPA 14 committee. > > > > THE SCENARIO > > > > I'm using NFPA 13 (2019) and NFPA 14 (2019). Facts: > > > > The FDC will be supplied with a pumper truck at 200 psi, as this is a manual > standpipe system. > > All pipe, fittings, and valves on the combined riser are rated 300 psi or > greater. > > The sprinklers are residential sprinklers, which only come rated to 175 psi > max — there's no higher-pressure listed option to spec around this. > > > > Since the riser is shared between the standpipe and sprinkler systems, I'm > trying to nail down whether that 200 psi FDC-boosted pressure is something > the sprinkler branch has to be designed/protected against, or whether it's > legitimately excluded from that side. > > > > THE DEFINITION CONFLICT > > > > NFPA 13 (2019), 3.3.235 - System Working Pressure: > > "The maximum anticipated static (nonflowing) or flowing pressure applied to > sprinkler system components exclusive of surge pressures and exclusive of > pressure from the fire department connection." > > > > NFPA 14 (2019), 3.3.24 - System Working Pressure: > > "The maximum anticipated static (nonflowing) or flowing pressure applied to > standpipe system components exclusive of surge pressures." > > > > NFPA 14's 2019 definition dropped the FDC exclusion that NFPA 13 still > carries. My understanding is the 2016 edition of NFPA 14 did exclude FDC > pressure, and the exclusion came back (worded differently, as an explicit > inclusion this time) in the 2024 rewrite. So in the 2019 pairing I'm stuck > with, NFPA 13 excludes FDC pressure from working pressure, and NFPA 14 > doesn't carve it back out. > > > > WHY IT MATTERS HERE > > > > NFPA 13 also requires sprinkler components to be rated for at least 175 psi > or the max pressure they're actually exposed to, whichever is greater — > separate from how "system working pressure" is defined as a term. On a shared > riser, if the standpipe side gets boosted to 200 psi via the FDC, that > pressure is physically present at the riser regardless of which standard's > definition "counts" it. > > > > My residential sprinklers are only rated to 175 psi with no higher-rated > alternative. If any part of the sprinkler branch could see more than 175 psi > — even from FDC boost — that looks like a rating gap unless a PRV goes in on > the sprinkler side of the floor control assembly. > > > > WHAT I'D LOVE YOUR READ ON > > > > In the 2019 edition pairing, is FDC-boosted pressure meant to count as part > of the standpipe's "system working pressure," given NFPA 14 (2019) dropped > the exclusion language that NFPA 13 (still) has? > > For a combined system on a shared riser, does NFPA 13's exclusion of FDC > pressure actually relieve the sprinkler branch from needing protection > against it — or does the "rated for what it's exposed to" requirement > override that once the riser is shared? > > Practically: with 200 psi possible at the riser and 175 psi-max residential > sprinklers with no higher-rated option, is a PRV at the sprinkler takeoff > mandatory wherever calculated pressure (inclusive of anticipated FDC > contribution) could exceed 175 psi? Or is there some other intended mechanism > — FDC placard limits, a different assumption about how the two pressures > interact on a shared riser — that I'm missing? > > > > Any insight into the intent behind the 2019 language change, and how it's > supposed to interact with NFPA 13's exclusion in a combined system, would > really help. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Joe Burtell > > > > > > > > > > > > Design Manager > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > D > > > > > > > C > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > 406-204-4653 (tel:406-204-4653) > > > > > > > > > > > > 406-861-4507 (tel:406-861-4507) > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > 3004 1st Ave South > > > > > > > > > > > > > > > > > > > > Billings > > > > > > > > > > , > > > > > > MT > > > > > > > > > > 59101 > > > > > > > > > > > > > > > > > > > > Office: > > > > > > > > > > 406‑247‑0470 > > > > > > > > > > > > > > > > > > > > www.summitfiresecurity.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > This is a commercial email sent by Summit Companies or one of its > affiliates, with an office located at 1250 Northland Drive, Suite 200, > Mendota Heights, MN 55120. 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