Double check valve and single check valves

[fabulous]

A double check valve is just as two single check valves in close series. It means that under negative pressure, the water momentarily bypasses the first check valve and causes it to close is stopped from going any further by the second stop valve which will close at the same time (assuming no air or dirt in the valve and pipe). A single check valve stops backflow, but amounts of "contaminated" water will pass back along the pipe before it closes. In theory , two single check valves along in a pressure pipe will jointly act as a double check valve, but the farther they are apart the more likely it is that something will act to stop them doing so. Possibly the shower maker has found it is easier to adapt a design by using single check valves either side of the mixer, instead of a DVC elsewhere, perhaps on the grounds of length of a DCV fitting. Because of the typical design of both types of check valve, they can restrict forward flow rates noticeably, and you should only have them if you really need them.

 

[drounding]

Thanks for that. I'll file it away for future reference.

 

[Shopcetera]

eh think youre on the wrong site?

 

[Jeff Knows]

Err, Fabulous