Leak test problems

Hello All,
I just plumbed a twin house with PVC foam core pipe. Using industrial grade PVC solvent (gray) and purple primer, I had numerous leaks on my 2" joints.
Testing was done with 5 psi air. I had no leaks on the 3 and 4" joints.
The first twin I had used mostly sch. 40 pressure pipe (red lettering)and had only 1 bad joint on the 2".
Any thoughts on what's going on?

Thanks,
Pete

Are you putting the cement on both the inside and outside of the respective parts and rotating them when joining the two? The small rotation helps to even out the cement and make sure there's some evenly all around.

Absolutely. I guess my real question is there a problem with the foam core pipe? I've been doing plumbing for 24+ yrs. I spent a
couple extra bucks using the industrial grade solvent for less likely having a leak. Just real strange having several leaks using the 2" foam core and not one problem with 3 and 4" foam core.
Pete

An air test can and will push air through the foam core, but if there are no exposed ends in the piping system during the test you should not see that problem. I fought with an apparent leak in my own water closet riser until I realized that the air was coming through the cut end of the foam core, which the test ball does nothing to seal.

If your piping has any chips in the outside surface of the pipe that would be a leak point with foam core.

If your joints are leaking, I would dump the solvent you have and go with the tried and true.
A fresh can of Oatey has never done me wrong.