
I found them in some PVC connections when I was looking for a way to attach my barrel.
They fit pretty good. (slightly too large, doesn't matter that much)
The two together cost me 6 euro's. Much better than the 16 euro's the other ones cost. (still not very cheap)

The connector I bought;

Gas tank;
I found out that they use EXACTLY the same ones for propane. It should have a fairly high pressure rating.

Another connector pic;
I found the smaller O rings in a smaller connection.
The pvc has a PN16 rating on it. Should be strong enough I think?

I have to make another hole in the bottom of the tank before I start to weld.
At the supplier of the PVC fittings, I found a large collection of pressure rated PVC piping. 32 mm, 40 mm, 50 mm, up to 100 mm.
Nice barrel source

And something for JSR:
