Quote Originally Posted by kings1527 View Post
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?
This is where I get mine:
http://www.mcmaster.com/#metric-o-rings/=p3nifs

I use 1.9 mm X 3.8 mm but I think the stock size is 2.0 mm X 4.0 mm. Either works but I guess the smaller one gets more seal since it has less surface area. Viton is a little harder then Buna-N.