flat lager in keg


I have a keg which had mixed gas pumped thro it at 1st…when the gas ran out I got tod that lager would be better off with co2…I have now got co2 but the lager is coming out flat…the regulator is set at 20psi ( by sombody who i bought it off ) the mixed gas ran out completely..the keg is quarter full at most…just a few days ago the mixed gas was doing its job..just gone flat since hooking up to the co2…it is being chilled thro a cornelous 110 chiller..? help…


  1. I take it you are publican with an outside temporary bar unit. I am assuming the container is about half full. If you were using 30/70 mixed gas for lager and you completely ran out then this would cause co2 to leave the liquid and become flat. If you now have it on Co2 it will now need to recharge and this needs to be connected back on your system for a few days. This may restore it, you haven’t mentioned a time period. Do not tamper with the gas.

  2. the mixed gas ran out on thursday and i put the co2 on yesterday…today the lager is still flat..only if i swish the glass the contents around it gives a sort of head for a few seconds… when i did connect the co2 to the keg there appeared to be a rush of gas into i believe the keg…a friend said that he had never heard of this…this seems to imply to me that the rush of gas initially meant that the keg was not fully preasurised…can you change from mixed to co2 on the same keg?…the co2 is keeping pressure up but no life in the lager…

  3. If you had a rush of gas going into the container then this would certainly mean it was not pressurised and gas has left the liquid into the space in the container, so you now have to reverse the process and this can take a couple of days for the pressures to equalise again. So all you can do is connect it to the keg coupler and wait, it cannot be rushed.

  4. thanks…can you advise me please…is it best to use co2 with lager and cider or am i better reverting back to mixed gas…i only drink lager or cider…if you were to put bitter onto co2 what would happen to bitter ?…thank you for your advise…im just mistified on how the keg could have lost pressure..i did disconect the keg once i knew that the gas had run out…did i do wrong there ?…thanks for your reply/support up to now…

  5. You are asking so many questions this leads me to believe you are unsure of what you are doing, with all the health and safety issues involved here, you should really talk to your local Brewery or Dispense Technician/Engineer so he or she can advise you. Sorry. :-/

  6. the keg could be leaking hence the rush of gas and flat.or you where selling keg when gas bottle was empty.i would still get an engineer as you should not be converting gas systems yourself as they are all colour coded for the different systems and work at different pressures

  7. chaps you have it all wrong im a engineer and from what i have read you should have got one of us in tampering with the gas system can cause some big issues for you especially if not knowing what you are doin. as for the keg you first should have depressurised the keg as you are changing gases, then filled with co2 and left for 24hrs the pressure on co2 gauge is also wrong which will give the drop gas the wrong pressure also,your best bet is to call tech services but if i was you i would stick with 60/40 and not co2

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