If it's serving a sprinkler system only and the main drain cannot flow a high-enough volume to match system demand, then you have to configure a means of testing that will, whether it's on the building or underground. If the building is equipped with a fire pump and/or standpipes, you can check multiple boxes at a time by flow testing those components and the backflow simultaneously.
On the one hand, this ongoing conversation is getting close to kicking a dead horse, as I sense that many are making this a bigger deal than it has to be. On the other hand, if discussion like this can help form a set of standard/best practices, then this requirement can be readily incorporated into new builds and hopefully retrofitted as needed to existing systems. Our industry is plagued by failed maintenance issues and we all should be as aware of and proactive as we can be on issues that facilitate implementation and enforcement of NFPA 25 nationwide. Steve L. From: Eric Rieve <e...@rievefire.com> Sent: Wednesday, December 14, 2022 10:40 AM To: Discussion list on issues relating to automatic fire sprinklers <sprinklerforum@lists.firesprinkler.org> Subject: [Sprinklerforum] Re: BFP on underground supply You'll probably get some pretty diverse answers depending on how one views the intent behind the provision. The commentary advises using the full diameter of the riser as the outlet size to theoretically allow the test to be performed without needing to measure the flow with a pitot or hose monster setup. While this is true, and does adequately provide for exercising the backflow checks, it seems very wasteful to install a setup capable of flowing system demand and then not provide a few more inexpensive components that would allow the setup to accurately measure the flow (and pressure) from a hydraulic design perspective. While NFPA 25 doesn't require this accurate measurement specifically for the backflow exercise, it does require verifying the system demand from the private water main feeding that backflow at 5 year intervals. Further, a fully functional flow test assembly has immeasurable uses when it comes to system modifications, and future water supply degradation testing that may someday be necessary. Finally, when filling out your aboveground certificate for system acceptance. I'd much rather know that I flowed system demand and maintained the appropriate residual pressure for the design as opposed to probably way overflowing demand through a full port opening and having an unusable pressure gauge reading. Every riser is different obviously, and we've arranged them all sorts of ways depending on the situation. Sometimes we've used the single main drain and just installed a brass NPT x NST adapter on the exterior fitting. Other times we've installed one or two 2.5" NPT angle valves on saddles directly after the backflow with nipples through the wall to NST adapters on the exterior. Sometimes if the riser room has an exterior door we've just thrown two 2.5" angle hose valves on saddles or a grooved Siamese inlet. Our larger warehouse systems generally get a butterfly valve inside and full derby manifold on the exterior when they start getting into the 800gpm+ range. If you install an arrangement that allows for accurate waterflow measurement then you can prove your assembly meets the requirements. Hope this helps! Eric Rieve Fire Protection From: Dennis Wilson <dwil...@blackhawksprinklers.com<mailto:dwil...@blackhawksprinklers.com>> Sent: Wednesday, December 14, 2022 12:01 PM To: Discussion list on issues relating to automatic fire sprinklers <sprinklerforum@lists.firesprinkler.org<mailto:sprinklerforum@lists.firesprinkler.org>> Subject: [Sprinklerforum] Re: BFP on underground supply On backflow testing, NFPA 13 (2019) 16.14.5.1 states the backflow needs to be tested at system demand. I have a hard cover copy, and in it the question was asked, if a 2" main drain would be sufficient, to do the backflow test. After their explanation, they say it basically needs to be the same size as your system riser, and using a larger drain valve would be a waste since the drain test is to be done more often. So what we've been doing is running a pipe outside the same size as the backflow, using a normally closed butterfly valve. Sometime routing around the FDC if it's a Storz. model. Our thought now is why not run several 2" drains out the wall. With 2½" & 3" backflows, we increase the main drain to 2" which is usually enough for system demand. Can always run a separate 1" insp. test also. With 4" backflows, you already need (1) 2" main drain, why not run a separate one for testing, that will give you (2) 2" openings, and run a third if you have a 6" backflow. And with multiple systems, run the main drains out separately instead of combining them together before you go out. Does this sound feasible, since all we're really trying to do is exercise the springs in the checks? From: Ed Kramer <e...@bamfordfire.com<mailto:e...@bamfordfire.com>> Sent: Friday, November 18, 2022 11:19 AM To: sprinklerforum@lists.firesprinkler.org<mailto:sprinklerforum@lists.firesprinkler.org> Subject: [Sprinklerforum] BFP on underground supply NFPA 13 is pretty clear that some method of forward flow testing a fire sprinkler system backflow preventer shall be provided. If the BFP is located at the system riser (very common in these parts), we provide the required means. So, who is responsible for providing the means if the BFP is located in a pit on the underground fire service, and the UG fire service (along with the pit/BFP) is "by others"? From a practical viewpoint, it's easy enough for us to provide that at our system riser, but are we required to do so? Or does that responsibility fall on whomever installs the BFP? I've not seen this addressed anywhere in bid/contract documents. Ed Kramer Bamford Fire
_________________________________________________________ SprinklerForum mailing list: https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org To unsubscribe send an email to sprinklerforum-le...@lists.firesprinkler.org
