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Advanced Member

Posts: 83

Location: Eastern WA


Tuesday, June 28th 2011, 4:08pm

1" backflow preventer in 1 1/4" mailline

I just realized that I might need 1 1/4" main line (poly pipe). Is it ok to use 1" backflow device since 1 1/4" costs twice as much?


Supreme Member

Posts: 5,292

Location: Metro NYC


Tuesday, June 28th 2011, 7:00pm

I've used one-inch PVBs with two-inch mainlines


Advanced Member

Posts: 83

Location: Eastern WA


Tuesday, June 28th 2011, 7:28pm

ok, seems like there's even no 1 1/4" size. I was looking at 1 1/2.


Supreme Member


Tuesday, June 28th 2011, 10:38pm

Size doesn't matter, performance at your designed GPM does. You need to look at a pressure loss table/chart for the device you are interested in and see if it's performance at your GPM works for you. Same goes for valves as well.


Supreme Member

Posts: 493

Location: Seattle


Wednesday, June 29th 2011, 12:51am

Size doesn't matter, performance does.
Kid Mode : That's what she said! :P

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