Advantage to Two-Clapper FDC?

9/5/2019

Many two-inlet (2 x 2-1/2") fire department connections I'm familiar with and commonly have a single-clapper, where the clapper will swing and cover the inside of the inlet on the side of the FDC not being used to prevent flow out of the other inlet.

Is there any advantage to having a double clapper?

One disadvantage I see is that you can't forward-flow test the backflow preventer out the FDC if there are clappers for each inlet.

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1 Comment

Mark

9/9/2019 07:48:44 am

I don't see much of an advantage for a two-clapper FDC, in my opinion. If there's only two inlets then a single clapper will prevent flow out of the opposite inlet when the first side is pressurized.

Depending upon the arrangement it might be possible that a two-clapper will be less of an obstruction for inflowing water than a single-inlet - but this usually isn't an issue for most basic sprinkler systems considering the pressure is supplementary.

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Advantage to Two-Clapper FDC?

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