Is there a way to use a CO2 cartridge to purge head space in a carboy? Or a growler for that matter?
I use an empty whipped cream dispenser. Obviously I use CO2 cartridges intended for soda siphons rather than nitros-oxide cartridges. There are simpler ways but I've just utilized what was already at hand.
there are a few inventions out there that use them for keeping growlers under pressure, I assume you could just not seal it up before opening the valve