Why do AM/MM/X/RT valves have two orings atop the on/off?

[Pneumagger]

Wouldn't one oring work as long it had material supporting the outside diameter?


It seems to me like fewer orings would be more desirable, if possible... so there must be a reason why there is two.

[Spider-TW]

The classic RT just had the one. Look at that mess.

The two o-rings just need a single machine step, compared to the one. You could shrink the on/off itself into a stack of o-rings and a pin, but the retention would change too.

You also get a little more play in tolerances with two o-rings as opposed to one.

I've always considered it tolerances and machining needs.

The ULT has just one. The lack of that shoulder in the valves allowed AGD to use a intermediate size o-ring without other mods.

[Pneumagger]

That was the answer I was hoping for... Thank you.