bjg122

M tanks. They use what looks like steel coupling.

The part that is a question is whether there is a good reason not to have any kind of flexible gasket to improve the seal. Metal on metal seems too intolerant to scratches, dirt, etc. I find it frustrating that it is so difficult to get a good seal. I would think that some kind of flexible gasket would improve the process. Sometimes, it involves switching to a different tank which produces a better seal. At 2 AM, that is a real bitch to do. It is tough enough to change a tank when it works perfectly.

Never overtighten! OK, I've had a number of times that I simply cannot get a good seal on an onboard oxygen tank. Since rubber washers work find with portable oxygen, is there any good reason why such a thing doesn't exist for onboard oxygen? Granted, the opening is bigger, but the pressure is the same.