Bleed air from terminated drain lines for leak check?

[Speede541]

I'm burying four terminated copper drain lines in my ceiling for future use -- three 2" horizontal drains that will serve future showers and a laundry, and one vertical 1½" drain that that will drain a sink.

All four are connected to an otherwise functioning DWV system that drain the current tub, sink & laundry.

The three 2" pipes are capped with Oatey test plugs. The vertical pipe is sealed with a copper end cap.

Being that these pipes are all capped and not yet in use, none are vented, so I imagine all four are trapping air when I do my fill & leak check from the bathtub on the floor above.

I'm wondering if I need to come up with a method to bleed the air out of the ends of the pipes? Or is enough to assume that, if there's a leak, the air will find its way out first, and the water will rise and follow?

http://www.oatey.com/Plumber/Shared/ProductGroupDetail/290/Mechanical+Test+Plug.html

 

[hj]

I never worry about bleeding the air, but since you have the wing nut plugs, just leave them loose until the water starts to leak from them and then tighten them securely.

 

[Sponsor]

 

[Speede541]

Thanks, hj. I did that to a limited degree, but because they're running flat, I think they're venting well when the water first reaches the end of the pipes. It's when they approach half-full and above that I believe the air is becoming trapped.

My concern is that my few connections that leaked all did so from near the tops of the joints, and one sat three days filled with water before it began dripping.

But I suppose the trapped air is exerting the same amount of pressure on the joints that the water would be, so in the end (hopefully) the result should be the same.

 

[hj]

The inspector is only going to be there 15 minutes for the test, and if it takes 3 days to start leaking it will NEVER leak when it is being USED as a drain.