A check valve for a 20 psi application should not have more than 2 psi lift value. You want to open the valve easily but you want it slam shut easily too. and seat properly. Maybe the Dennerle is all teflon(including the spring). But really any type of check valve should work

Definitely getting into details over my head now. :lol: All I know if I blowed as bloody hard as I possibly could into it and could not get it to, er, pun-not-intended, pass air. But put it on the CO2 line and the CO2 would pass no problem (even at really low psi settings, although I still have to run mine at 18-20psi just to produce a consistent bubble rate). So, that, and the fact that it's still working four years later. I was going through those clear plastic check valves like crazy. Not that they're expensive but it's just annoying when they stop working and you have to replace them.

The reason for the difference in the lift value is because most lift check applications involve pumps. Sometimes pumps need some large backpressure to operate efficently. In passive applications a 1 or 2 psi lift is it. The most important point in check valves is how well it seats back to prevent backflow. Tony i suspect yours spring loaded poppet and the cheaper ones are a flappper type.

Thanx. I saw that one on Marine Depot as well and was considering it also. I'll get in touch with OA. Thanx for all the replies.

Cheers,

Thanx for that link, Tony. OA doesn't carry it (or any other Canadian outfit, it seems, for that matter). I placed an order with Aqua Cave. We'll see how it goes.

Cheers,

mark; let us know how it does go!
thanks