Leaking Gaskets on Brand New Backflow Preventers

Alan (California Radiant) Forbes

These backflow preventers, all brands have flat, fiber gaskets that always leak on installation. They're the same gaskets on other devices, like Caleffi's fill valves, but those never leak. Only on the backflow preventers.

We now dope the gaskets on backflows. It's a messy job and I wonder what others do.

STEVEusaPA

I usually just wet fiber gaskets, especially the Watts ones on the radiant fittings. Usually buy the feed/backflow combo, hadn’t noticed any leaks.

hot_rod

Be sure both surfaces are clean, good alignment, and wet the fiber gaskets before you install them.

Don't over tighten, a 10- 12" slip joint pliers should be plenty of tool.

Or use a thin layer of pipe

Finding a gasket compatible with all the various chemicals being added to public water these days is becoming a challenge.

JUGHNE

Replaced a 1/2" 760 from 2013. Hoping for a simple change out.
The union nut threads were different, had to change the spud nipples.
The replacement seemed to be slightly longer.
Rubber type washer gaskets were a pain, both leaked. Take apart and redo, easy to overtighten.

Intplm.

Clean and clean again the gasket and face of the BFP.
Then I use a little bit of plumbers, or heat proof grease on the gaskets.
Works every time