Draught Operations > A Matter of Balance > Mixed Gas

As we have seen, beer readily absorbs carbon dioxide.  Any change in CO₂ pressure on a beer results in a change in the carbonation of the beer.  Nitrogen is different.  Beer does not absorb nitrogen gas to any significant degree.  This means we can apply nitrogen pressure to beer without changing the properties of the beer.  Thus, in high resistance draught systems, we use a mixture of CO₂ and nitrogen to achieve two objectives: 1) maintain proper beer carbonation and 2) overcome the system resistance to achieve a proper pour.

The exact mix of CO₂ and nitrogen depends on all the factors we have discussed: beer temperature and carbonation, system resistance and the total applied pressure that’s required. Those interested in the details of these calculations can see Appendix C.  While some systems use a premixed blend, other installations may require a custom mix created from separate nitrogen and CO₂ tanks by an on-site gas blender.

Next Topic: Dispense Goals >