We've got a project where we need 8" UG for the calcs, and the main in the street is 6". 6x6 tap, increase to 8, we're on our way. The water purveyor is not going to replace a block or two of existing UG. And look at 13D systems- certainly not unusual to have a 3/4 UG supply increased to 1" for the sprinkler riser after the tee.
glc -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Cliff Whitfield Sent: Thursday, November 11, 2010 8:59 AM To: [email protected] Subject: RE: reduce then increase pipe sizes Todd, I've seen this done in the past. In fact, there are a lot of times when it's done by the water purveyors during a tap on the main underground line. Not sure of a specific code reference. If common sense is an option you can point to NFPA 20 that allows a smaller size supply to feed a fire pump (ie 6" line feeding an 8" pump) if you go a certain number of feet (in pipe diameters) back and increase the pipe at that point. I believe the whole basis for hydraulic calculations is that if you can prove it works within the boundaries set forth in the standards then it is acceptable. You can reduce pipe sizes to balance a system when you are working with foam. I don't think this is really any different. Cliff -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Todd Williams Sent: Thursday, November 11, 2010 7:51 AM To: [email protected] Subject: reduce then increase pipe sizes I am working on an existing system where we have to tie in a new 2-1/2" main into an existing 3". Since they do not make a 3x2-1/2 mechanical tee, that option is out. My proposal is to utilize an existing plugged 2" outlet, install a 2 x 0-6 TxG nipple and then increase to 2-1/2". It works hydraulically with 18+ psi left over (reducing the 2-1/2" main not an option hydraulically). I don't see anything in the Code that states that it is not allowed. However, the AHJ says it isn't. Before I argue the point, am I missing something? Todd G. Williams, PE Fire Protection Design/Consulting Stonington, CT 860.535.2080 www.fpdc.com _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
