Travis - we've already talked about this project, I think. The requirement for the collection drain is that it be one nominal pipe size larger than the largest discharge connected to it. If the standpipe has a drain that's connected to this collection riser, then I'd agree with the AHJ. But if the standpipe is being drained independently from a hose valve or an aux drain, then I believe you've met the intent of the standard(s).
The foregoing is my opinion only and does not necessarily represent the opinion or intent of the NFPA 14 Technical Committee on Standpipe and Hose Systems, or the NFPA 13 Committee on Residential Sprinkler Systems. Steve Leyton Protection Design & Consulting San Diego, CA -----Original Message----- From: Sprinklerforum [mailto:[email protected]] On Behalf Of Travis Mack Sent: Tuesday, August 12, 2014 10:06 AM To: [email protected] Subject: Drain riser NFPA 13R We have a project that has a combination standpipe. Due to an issue with the AHJ interpreting the minimum sizing for a combination standpipe, we have installed the standpipe as 6". This is a project designed per NFPA 13R. Each floor control valve coming off the combination standpipe is a 2" floor control valve assembly (b'fly valve, check valve, flow switch, gauge, test-n-drain). The test-n-drain is 1" per NFPA 13R. Each 1" drain line ties into a common drain riser. The common drain riser was indicated as 1¼" and approved this way. Now, the inspector is stating that is has to be a minimum of 2". They are stating that since it is attached to a standpipe "riser" that is larger than 4", the drain riser must be 2". I believe this is an incorrect rationale and that technically a 1" drain riser would be acceptable because NFPA 13R only says that you must do a minimum of 1" drain. The drain was upsized to 1¼ because of the requirement in NFPA 13, but it is technically not applicable. What is the general forum consensus on this? Is a 1¼" common drain riser acceptable because it is connected to 1" floor control drains. Or, is the common drain riser required to be 2" because the floor control assembly is connected to a 6" standpipe? It would not have been an issue earlier, but all drain risers are installed. -- Travis Mack, SET MFP Design, LLC 2508 E Lodgepole Drive Gilbert, AZ 85298 480-505-9271 fax: 866-430-6107 email:[email protected] _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
