One way plumbing valve- pressure needed?

[Lowdown3]

On say a 2" or a 4" PVC pipe, if you had a one way valve, realistically how much pressure is necessary for the valve to open?

What I am getting at is thinking about using either a 2 or 4 inch pipe for drainage of an area but the water will have very little pressure or almost no drop. With the idea being that the valve will open to release drainage water outside the building.

Do you suppose the valve will open and work effectively with that little pressure? Does the size of the valve matter? Can possibly go down to 1 inch pipe if need be but prefer not to.

[Dennis W]

I just tried a new 1" valve that I had on the bench. If you blow in it it opens pretty easily. Don't know how much pressure that is though. If your just trying to keep critters, gas or what ever from coming back up the pipe, you could just put a water trap (like on your sink drain) on the end. Just use 3 or 4 90 deg elbows together.

[Lowdown3]

I just bought one to try also :)

My thoughts more or less were to have a line kind of like a drainage pipe with the holes 3/4 of the way around and 1/4 solid. So that any water could enter the pipe once it got a half inch or so high. Then at the end it goes through the check valve so that nothing from the outside flows back in.

[cpt_sfc]

One way water. Boston whaler has a pc of soft plastic on a hinge in the back of there boats , boat moves forward water goes out boat stops water stays out. If it has a seat to rest on should be easy to open/close except for trash. If in a pipe a plastic ball that floats up and down might work.