This was touched on in another thread and I've been wondering about it for some time myself. There is often a reference made to check valves in membrane type diffusers. I was under the impression that it was more a case of a check valve "action", due to the slits in the membrane going closed when not under pressure.

Is there in fact a mechanical, dedicated type of check valve, or is it simply a type of automatic function of the membrane construction? I can see where having a mechanically actuated valve might be problematic....(cleaning, repairing, etc)

"Forget pounds and ounces, I'm figuring displacement!"

If we accept that: MBG(+)FGSF(=)HBG(F1)
And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1)
Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT?
PB answer: It depends.