Somewhere in amongst my piles of moving boxes I found one of those Sparklets gizmos. Attach to the top of the can, 4 or 7 size, screw down and pull lever to serve. Sparklet CO2 cylinder repleneshed gas in can and kept it"fresh".
I'll se if I can locate it, but it may have gone to great bar in the sky by now.
Were there "more hops in Ben Truman"?