Hi DIY punks! I need a little help with something. I’ve been trying all sorts of ways to home carbonate things as sustainably as possible. Most have not really worked out as intended, but I’m really really close on this latest attempt. This version is to connect a CO2 tank to a whipped cream dispenser.

Basically, the path from the tank looks like this:

• 5 lb CO2 tank → dual gauge primary regulator.
• Regulator → 5/16" hose.
• 5/16" hose → 5/16" barb to 1/8"NPT male.
• 1/8"NPT male → 1/8"NPT female to 8mm female quick disconnect.
• 8mm female quick disconnect → 8mm male quick disconnect to 3/8"-24UNF female.

…and the path from the dispenser looks like this:

• 1Qrt ISI Gourmet Whip M22 Male → M22 Female.
• M22 Female → “mystery hose”.
• “Mystery hose” → “Mystery connection” male.

So, I need an adapter to hook up the 3/8"-24UNF female to the mystery connection. It seems to start screwing in for a couple turns, but then won’t go any further, so my guess is that it’s the same diameter with different threading? Note that, in the link for the mystery hookup, I removed the TR21-4 at the end, because that’s for directly hooking up to a small tank. The mystery connection I’m talking about is the male threaded part you can see screwing into the TR21-4 connector.

It doesn’t seem like many people are doing this, or know what most of the industry standard connections actually are. See this thread here for example. Consequently, I have no idea if the mystery eBay hookup I bought even works, despite that being its entire purpose. The interior of the CO2 cartridge puncturing mechanism is a black box to me, so I’m just trusting this M22 connection is all that’s required. There’s definitely some kind of one-way valve in there, but hopefully it doesn’t somehow require being “pushed” by the cartridge itself.