how do you test to see if beer or larger is flat


just started at a pub would just like to know once you serve a pint how do you test to see if beer or larger is flat. The reason i ask is that my manager showed a customer by hitting the top off glass with a bottle which by doing this the gas rose upwards is this the right way or fooling the customer thankyou.


  1. The only proper way other than using special brewery equipment is to taste the beer or lager. The sad thing these days is that people tend to drink with their eyes expecting lager to be effervesing like an Alka Seltzer in a glass of water or if drinking bitter for it to have an enormous whipped cream head.
    Widgets at the bottom of glasses are used on most big name lagers and similarly diffusers on nitogenated beers[cream flow], are all designed to release co2 or co2/nitrogen mix gases from the beer.
    Getting back to your question, hitting a glass of beer or lager as a way of determining wether it is flat or not does not make sense. Even flat beer will have some residual gas within it. Tapping the side of a pint demonstrates nothing.
    Ultimately if a customer has complained of a flat pint the then that customer obviously thinks that the pint is flat, right or wrong. A bit like having a bad steak and complaining only for the chef to tell you it is not!
    The answer is to offer the customer something else and then determine if the beer is flat or not, using your own judgement and knowledge. Some authentic bottom fermented lagers such as Carlsberg do not display vast amounts of gas bubbling away after it has been served, but are perfectly good. Carling on the other hand is totally different, it has a higher co2 volume and coupled with glass widgets it will bubble away all day.
    The point is a visual check does not determine if a beer is flat or not. If in any doubt take the keg off service and give tech services a ring.

  2. 1 wrote:

    • ImportantWhen using the Inn Doctor site it is important that all relevantBrewery Technical Services regulations and advice and Health and Safetyregulations are adhered to. The advice we give does not ask you tointerfere, adjust, or in any way tamper with beer dispense or ancillaryequipment. Inn Doctor is a means of systematically checking your beerdispense equipment for faults, in accordance with recognisedprocedures, issued by the major Breweries. You must seek professionaladvice in relation to any area covered by this website in respect ofwhich you have any doubts whatsoever.

      Do not tamper with beer dispense equipment. please read our <a href="">Disclamer</a&#62;

    Agreed.Look.observe,understand.Should you be uncertain of what you see leave it alone.There is no mystery,anyone who is any good is accepted,entirely dependant upon their attitude.If you don’t know what you are doing leave it to those that do.

  3. 309 wrote: hi
    just started at a pub would just like to know once you serve a pint how do you test to see if beer or larger is flat. The reason i ask is that my manager showed a customer by hitting the top off glass with a bottle which by doing this the gas rose upwards is this the right way or fooling the customer thankyou.

    A good way to tell how much gas is in the lager is to hold some beer in your mouth and feel how much it tingles on the roof of the mouth the more the better.

  4. In the good old days when we could smoke in pubs if you flicked a bit of fag ash in the drink it would certainly make it effervesce. If it didn’t it was flat, however I would only recommend doing this with a bit of beer left in the glass as it would make the rest undrinkable. But by then you would have drunk your beer anyway, so this makes what I have just written pointless,……… note to oneself do not go on the computer after you have been down the pub. 😮

  5. Quite often I have a problem with so called ‘flat beers’ (including lagers). Check the gas in the cellar, make sure it is turned on, make sure the fob is clean and full. Check your glasses, when were they last rennovated? You’ll all know when you last cleaned your lines for stocktaking purposes.

    However dealing with the eyes that are drinking the beer, because obviously the mouth is an optional extra and not for tasting beer withis a different art, (think about downloading a different language or accent and see if that works). I normally look at how much has been consumed and whether or not the ‘customer’ (who is never wrong, but even rarer to be right) has been drinking elsewhere or has complained before over a beer. Try changing their glass and topping it up if less than a third gone, if that dosen’t work then offer them something different, especially if they only drink that one product in your establishment.

    That’s normally the clincher, they’ll tell you then that it was probably the curry they had earlier in the month, or that they were upset over grannies budgie just pegging out like that and that the pint is already tasting better. Check with other customers as well, one customer lets say Bert was a large well built Yorkshireman who had lived away from (gods) county for many if not all of his odorous years, his aftershave was a dead ringer for that fancy french stuff made with garlics and snails and pigs trotters, we used to shorten it to BO for short or if a lady was with him we’d call and check to see when our next specsavers appointment was due.

    Anyway nothing good was made outside of the ridings and this despite the fact that on a good day 15 or so of these p*** poor ales would depart from our cellar and be recycled via our urinals (and his own WC). Every 3rd pint or so he’d find a reason. (no ‘ead, flat as a witches ***, sumfing floating there(normally a piece of cheese and onion crisp from the packet he was munching, at least the smell of them was better than his aftershave) or just somfing jurst not right with that beer, it wouldn’t happen where I come from I’ll tell yah lad.) this related at normally just a few decibels less than a Squadron of Challenger tanks warming up and therefore definitely not the sort of publicity a new aspiring landlord wants for his business.

    After falling for this trick for a week we decided on a plan of action that included taking the offending ale away and replacing that one pint with something else, which didn’t go down well but at least we’d agreed with him so he couldn’t complain. After less than a week he was down to bottled beer only or to admit defeat, couched in terms of victory for himself, so on that Saturday morning we opened up, lines had undergone usual clean, glasses had just been renovated and he asked quietly (just the 1 Challenger warming up) if he might try some of his favourite ale as he had heard I had a new barrel in.

    Well we discussed it for a minute whilst I pointed out that that the brewers had just increased their prices (blurry grave robbers) that they had just reduced the strength again ( blurry grave robbers)(featured again) but eventually I placed upon the bar a pint of the foaming nectar perfectly presented. The pint was sunk and a great smile lit upon his face when at that moment my wife walked in from shopping, walked towards us, then stopped and sniffed the air, walked a little closer and loudly proclaimed (decibels of a Tornado approaching on a final bombing run) that unless Bert got his Lumbar vertebrae, Sacrum and Coccygeal vetebrae out of her pub and came back later in some clean clothes and having washed his whole body preferably in bathing salts and bleach (which he misheard salted beef) he would be the star attraction in her new pond which was just awaiting a lining at that moment. He turned walked out of the pub still with a smile upon his face.

    A small round of applause broke out from some of his cronies and they took it in turns to supply her with 1/2s of cider. 2 and a half pints in, she’s not a large drinker, so I guessed we were eating out again that night at the local Chinese when Bert returns still with a smile on his face, freshly bathed and shaved and clothes we never knew he possessed. He ordered a pint sat down with his mates and told them all in his usual style that for a Londoner my wife must have had Yorkshire ancestors and that he would be pleased to do any heavy jobs in the garden for her in future.

    Six years on now and sadly Bert no longer comes in though his picture adorns the wall near where he sat. We lost him very quickly to an industrial form of cancer, just 5 months from diagnosis to that great furnace in the local crem. During the 5 years we had known him those were the ones which transformed our outlook on people and on their wiles and whims. He never found fault publicly with the beer again, most of the garden’s digging was down to him, and as requested by him his ashes were scattered there about 3 months after he left us. He died intestate with no living relatives that could be found, though that can’t be settled for a while yet.

    If however you are serving flat beer apologise and sort it, eg change gas, clean line, clean glass and sort out the other glasses asp, or give tech services a call.

  6. How to change flat larger into an interesting article, thank you for sharing it with us. It is funny how certain people impact on our lives, the type of people you would probably would never have met unless you ran a pub. It is not my place to change anything but it was difficult to read so I put some paragraphs in I hope you don’t mind?Great story :K)

  7. I think Old Bert may have tried that trick on with me, crafty old bugger. Still from the tone of your very funny post I think you may have developed a liking for the old gent. It’s old characters like him that make a pub. R.I.P. Bert. Just think there is a heavenly bar somewhere with OLd Bert trying it on with with the angelic landlord. Now there’s an oxymoron for you.

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