how long should a standard bottle of CO2 last when used with 11 gallon kegs. we seem to be using one nearly for each keg.
Not sure how many kegs to a bottle you would get, it also depends if you are using gas pump as well.
However we do have a post in the forum which can give up to 14 kegs from a mixed gas bottlehttps://www.inndoctor.co.uk/answers/how-many-11s-37/
You obviously have a gas leak somewhere and should immediately call out Tech Services and keep the cellar well ventilated.
Co2 can be dangerous perhaps you should read this post as well. https://www.inndoctor.co.uk/answers/is-it-now-time-for-every-pub-to-have-co2-detector-481/