Quote Originally Posted by Bitsyncmaster View Post
Buna-N will swell with todays gas. Look at that O-ring after it sits out on the bench awhile. It should get smaller. I did a swell test measurement back on the old .com forum but don't have a copy of my results.
Interesting. That might be why my old o-ring was noticeably larger. I did a lot of research on the material and it said it was compatible with gasoline. What other applications would Buna-N be used for?

I still have a Viton check valve on the way so I'll probably just swap it out and be done with it. Any idea how long it takes for Buna-N to deform?

Who has a good source for Viton o-rings for the PPR?