The ones of these I’ve seen look identical to the "industrial" pattern of 1/4" air hose couplings.
Does anyone know if that is actually what they are, or do they just look similar?
(I don’t think air hose couplings are made to be tight under negative pressure, but they could be. I’ve found they are often not well made and leak air if there is any side pressure on them.)
I’ve found that they vary a good bit in the diameter of the area between the hex and where they neck down. Not sure if there are multiple standards at work.
At Tomahawk two years ago there was a whole trailer of Champion stuff–motors, tanks, hoses…. I hope all that stuff was preserved.