Todd, Like Brett mentioned, going vertical to eat up pipe length is shown in the annex of NFPA 20, and I’ve seen/used that approach before. When you say there is a problem with the test, is this for a new fire pump installation? Are you not meeting your curve, and if so, are you off by a substantial amount?
I was always under the impression that the un-balanced flow caused by the elbow being to close to the suction inlet was a “long-term, causes damage over time” sort of issue, so if your problem is on a new install, I’d want to double check that there isn’t some other cause. 38” of straight run obviously isn’t great or to code, but it’s not like the elbow is directly attached to the suction flange either. Backflow has OS&Y valves right? Hope this helps, Eric Rieve Rieve Fire Protection From: Fpdcdesign <[email protected]> Sent: Friday, July 14, 2023 12:37 PM To: Sprinklerforum <[email protected]> Subject: [Sprinklerforum] Elbows in pump suction I am working on a pump house that has a 1500 gpm pump with an 8” suction line (no reducer). There is an elbow in the suction line parallel to the pump shaft with a piece of pipe that is 38” from the suction flange and there is a problem with the test. We have to add another 42” from the parallel elbow to the flange. There is physically not enough room in the pump house to make it in a single straight run. My proposal is to turn the offending elbow looking up (so no linger parallel), add a 42” vertical piece to an elbow and pipe that back to the discharge from the backflow preventer. Can the 80” be split into 2 pieces? NFPA 20 says nothing about that but I was wondering how it works in real life. FYI, the backflow discharge is already over the 80” threshold. Todd G Williams, PE Fire Protection Design/Consulting Stonington, CT 860-535-2080<tel:860-535-2080> (ofc) 860-554-7054<tel:860-554-7054> (fax) 860-608-4559<tel:860-608-4559> (cell)
_________________________________________________________ SprinklerForum mailing list: https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org To unsubscribe send an email to [email protected]
