CO₂ vs Mixed Gas

The short version

Lagers and ciders typically use CO₂. Ales and stouts usually need mixed gas (CO₂ and nitrogen) for a proper head. Guinness is poured on 70/30 mixed gas. Leffe is listed on 60/40. We match the gas and regulator to the beer, then set the pressure on site.

This page is the gas guide, not an online calculator. If you hire the kit, you do not need to set it yourself.

CO₂

Carbon dioxide is the usual gas for lagers and ciders. It keeps the beer carbonated and pushes it to the tap. Wrong pressure shows up as foam or a flat pint — see how to use a beer tap.

Mixed gas

Mixed gas is CO₂ with nitrogen. Ales and stouts usually need it for a stable head. Straight CO₂ on a stout often gives a wild, fizzy pour. Nitrogen without enough CO₂ leaves the beer flat.

Guinness is the clear example: U-Type coupler, 70/30 mixed gas, and a cooler. That is how we pour Extra Cold at weddings and on office bars. See Guinness keg hire.

What we set, and what we do not publish

Regulator pressure depends on the beer, the temperature, the line length and the cooler. We set it when we install the system and run a test pour. We do not publish a one-number PSI chart, because copying a pub cellar setting onto a marquee python is how you get a foam tap.

Tell us the brands. We supply the correct gas, coupler and cooler together. The keg coupler guide covers the head. Cooling is a separate problem — see keg cooling for events.

Common faults

• Too much foam: often warm beer or pressure set too high, not always the gas mix.
• Flat beer: leaking coupler, empty cylinder, or the wrong gas for that style.
• Guinness that will not settle: usually not 70/30, or the keg is too warm.

If you already have kegs and only need the dispense kit, that is still draught system hire. Add keg hire if you need the beer as well.