Mini CO2 regulator (cartridge): 5/8-18 UNF inlet for a 74g threaded cartridge; 1/4" MFL (7/16-20 UNF) or 1/4" FFL outlet, compact cartridge-fed CO2 regulator, seals on cartridge seat at the inlet; flare face at the outlet. What it fits and the adapters to join it to other keg fittings.
Updated 05 September 2026.
Mini CO2 regulator (cartridge) (5/8-18 inlet, 1/4" MFL out)
Where 5/8-18 inlet, 1/4" MFL out is used, its real dimensions, and how to connect it to other keg fittings.
Published dimensions
- Designation
- 5/8-18 inlet, 1/4" MFL out
- Size / thread
- 5/8-18 UNF inlet for a 74g threaded cartridge; 1/4" MFL (7/16-20 UNF) or 1/4" FFL outlet
- Fitting form
- compact cartridge-fed CO2 regulator
- Seals on
- cartridge seat at the inlet; flare face at the outlet
- Rating / role
- a small regulator that runs off a 74g threaded CO2 cartridge instead of a full tank
Used on: portable and small-batch kegging, carbonating a single keg off a 74g cartridge with a real regulator.
A mini regulator threads a 74g (5/8-18 UNF) cartridge on its inlet and presents a 1/4 MFL or FFL flare outlet, so it connects to a ball-lock disconnect exactly like a full regulator. It is not for refillable CGA-320 tanks; match the inlet to the 74g cartridge thread, and mind that a cartridge holds far less gas than a tank.
Flare fittings seal on the 45 degree flare face and must never be taped. Push-in fittings seal on an O-ring against the tube wall and need the tube cut square. Barbs seal under a worm clamp. Getting the sealing method right matters more than the thread label, because most homebrew leaks are a taped flare or an unclamped barb.
Connect this fitting
Questions and answers
What is the designation of the Mini CO2 regulator (cartridge) (5/8-18 inlet, 1/4" MFL out)?
5/8-18 inlet, 1/4" MFL out
What is the size / thread of the Mini CO2 regulator (cartridge) (5/8-18 inlet, 1/4" MFL out)?
5/8-18 UNF inlet for a 74g threaded cartridge; 1/4" MFL (7/16-20 UNF) or 1/4" FFL outlet
What is the fitting form of the Mini CO2 regulator (cartridge) (5/8-18 inlet, 1/4" MFL out)?
compact cartridge-fed CO2 regulator
What is the seals on of the Mini CO2 regulator (cartridge) (5/8-18 inlet, 1/4" MFL out)?
cartridge seat at the inlet; flare face at the outlet