Beer Gas the Cellar and Colour Coding

Mixed Gas Bottle 30/70

Is it possible to use the wrong gas in your cellar? No you say there are different fittings for Co2 and mixed gasses. But if you didn’t know already there are at least three different blends of mixed gas used in the cellar. So it is possible to connect the wrong blend of mixed gas.

We can start by identifying the different coloured gas pipe used across your cellar equipment.

Blue Pipe:

Air from the air compressor. Used to drive the gas pumps.

Grey Pipe:

Co2 Gas – used these days primarily for lager and Ciders, and maybe a few bitters. Some breweries insist Co2 is used so as not to change the taste of their beers.  And a electric or gas pump is then used to pump the beer to the tap.

Green Pipe:

Mixed Gas 30/70 – used for dispensing Guinness, Mild and Smooth-flow bitters. Nitrogen is now added in the brewing process to make the Smooth-flow bitters creamier.

Purple Pipe:

Mixed Gas  50/50 – used for dispensing Lager and Ciders, however you will find white pipe more commonly used.

White Pipe:

Mixed Gas  60/40 – used for dispensing Lager and Ciders

Mixed gas is a blend of Co2 and Nitrogen, in beer dispense Co2 holds the gas in suspension by being at a slightly higher pressure than the top pressure in the container while Nitrogen unlike Co2 does not get absorbed into the beer, so is used to push it up the line to the tap.

Check colour coding as well as the label

The first digits of the bottle labelling represented Co2 followed by the nitrogen. So Mixed Gas 30/70 would be 30% Co2 / 70% Nitrogen and Mixed Gas 60/40 would be 60% Co2 / 40% Nitrogen. But I now see some gas companies marking their labels the other way around. So perhaps someone could clarify this. So to be safe, always look for the colour coding as well.

Now I come to whole point of this article, Always make sure you use the right mixed gas bottle because it is possible to connect a Mixed Gas 60/40 bottle to a Mixed Gas 30/70 system, and if you do and do not notice straight away, it will cost you some serious money because it will make all your Guinness, Mild and Bitters containers un-servable you will see fobbing on a scale you have never seen before.

This usually happens in a Pub that doesn’t use 60/40 gas. The Landlord relies on the gas company to supply the right gas, but as you know in the real world anything can happen labels drop off etc. So always check and if in any doubt ring your supplier. One of these days they may start using different bottles for the different blends but I can’t see that happening for a very long time, so be vigilant.


  1. I always understood that if there is more than 30precent co2 with a balance of nitrogen the co2 will precipitate out of the mix. So depending on the temperature wth a 50/50 ‘mix’ you’ll
    actually only get 30co2/70n2 out of the top of the bottle and 100% co2 when you get to the bottom or vice versa if a dip tube is used. To get a stable co2/n2 mix of greater than 30% CO2. you need to mix on site with a blender.

  2. I have had a member of staff use a 60/40 gas on john smiths which is usually 30/70, is there anything that can be done or will the rest of that keg fob?

  3. I have a keg of Coors light and I’ve been sold 50/50 gas for it , just foam coming out , any ideas

    • Did it work ok before with 60/40 gas, if so it will need a gas adjustment. You haven’t said in what context you are using this.

    • In a word yes, we use 30/70 on outside bars it’s ok as long as the product is selling quite quickly, after a few days the gas might leave the product slightly leaving it to taste a little flatter. Just hope your customers don’t notice.

    • In a word no, if you don’t sell the container quick enough it will go flatter as the container empties. Some people will notice others won’t. 60/40 isn’t used on bitters anyway (60% being Co2), which is what you are calling nitro beers. 60/40 helps the lager etc dispense faster than it would by just using Co2. Otherwise they install a gas pump.

  4. We run Coors Light, we don’t have a cellar, the barrel, the gas and the cooler are all behind the bar. Because of temperature we have been advised to use a mixed gas rather then co2 to limit fobbing Does this sound right, if so which gas would be best?

    • Coors Light on an under bar setup may give you fobbing issues. If keg is at ambient temperature rather than the recommended 12-14 deg c during busy periods you may find you have fobbing as under counter cooler struggles to cool.

  5. HI >>>I am starting a mobile prosecco and beer truck and the company I bought it from who kitted it out have told me to use CO2 for the prosecco and 60/40 for my peroni, they have fitted the adaptors accordingly, however a peroni supplier has told me I should be using just CO2 not 60/40 for the peroni. Can you give me some advice please?many thanks.

    • Alison. Peroni are not keen for it to be dispensed on a 60/40 mix. Though it does dispense ok. With a mobile bar set up 60/40 is a better option than co2 with lager and ciders, the higher pressure of the gas helps to keep fobbing in check. Prosecco on 60/40 would possibly be a little less fizzy than on co2.

  6. Can you please tell me what a pub should use for stella artois please as my husband says hes stella is always flat and no head on his pint..should it be c02 or 60 40 ..I would be grateful for a reply just as a matter of interest …thank you

    • You can use Co2 or 60/40 mixed gas. Though some brewers prefer Co2 because of what you have said, it happened in my local when they changed over to 60/40. But what you are describing the reasons could be many it would be better to call out tech services to check out pressures, speed, glasses etc.

  7. Sounds like it is on a very low setting. Before the introduction of 30/70 gas it used to be set at about 10 to 12 psi. Over that and it will fob but it all depends how long it is on sale etc.

  8. We have just had east coast smooth added and with cellar services knowledge / advice are running through a previous line whilst awaiting new python, they said if the water cooler was really cold it might affect the beer. New 70/30 cylinder but it comes out like a lager, bubbles but not the smooth creamy appearance you would expect. any ideas

  9. Hi is CO2 only best for lager’s ill be running 1 line only for home use (1st timer) itll be carlsberg 11g would co2 be better than 60/40?

  10. Probably better to use 60/40 if you have a home bar and wish the lager to last a little longer. Always lift the keg couple when noy in use.

Do you have a better answer? Leave a reply or an opinion