The backflow should be sized for its design flow at 15 fps per it's listing. Conversely, I've seen them oversized, or 'pipe sized', just like PRV's. TD
That brings up another point I have noticed, mostly by U/G contractors. They place a smaller backflow inline, and then come back to pipe size. In other words, 6" piping, 4" backflow, and then back to 6". I know it is done to save $$$. But there is no code reference to say you can't. I found the answer in the listing. A 4" for example has a rated working gpm of 500. It is UL tested to 750gpm. If your system demand exceeds the "maxed out" gpm of the device, what impact will there be on the backflow attempting to flow these demands in subsequent years? R/ Matt _______________________________________________ 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)
