Originally Posted by ronhanson
It looks like just a simple check valve and I recall reading a few reports of these things failing so they have their faults as well. It seems more like a solution looking for a problem. Making sure water is in the trap is pretty easy, fool proof and happens automatically every time you use it.
Hmm, funny as the picture in the FMCA magazine didn't look like just a simple check valve at all. I really don't see this as a check valve in the sense you think of. Here is a Youtube video
demonstration. There are several that show it and how it works. Also one that shows testing it with a column of water till it fails, Took quite a bit, I was surprised.