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  • CO2 & caustic

    quick question for anyone who can set me straight. My brewpub recently added a walkin and we have begun serving only through kegs. For lack of a better option, fancy keg cleaners and the like, for cleaning the kegs I have essentially filled a barrel or so of hot water & caustic or acid into a brite tank, pressurized said brite tank, filling each keg with a small amount of chemical and shaking each vigorously by hand....then giving them a hot water rinse at a McGyver like sink area with connections to rinse/pressurize. Now Im second guessing myself because I seem to remember that CO2 neutralizes caustic. So is this method essentially worthless when done with caustic? Or does it take some time to neutralize? These are used kegs so I want to make sure they get as clean as possible obviously. Any input appreciated. Cheers.

  • #2
    Yep - Caustic is neutralized by CO2.

    Cool video showing the reaction!

    Carbon dioxide is a weak acid. It first neutralises the sodium hydroxide solution (causing the indicator to change from purple to green) and then produces a ...
    Cheers!

    Jeff
    Carbondale Beer Works

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    • #3
      I was told that mixing CO2 and caustic would cause a tank to explode. Anyone out there hear the same?

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      • #4
        It would actually implode, if anything. The gaseous CO2 is being consumed by the reaction, resulting in a net negative pressure.
        Sent from my Microsoft Bob

        Beer is like porn. You can buy it, but it's more fun to make your own.
        seanterrill.com/category/brewing | twomilebrewing.com

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        • #5
          That was it. Explode or implode. Either way, someone can get hurt.

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          • #6
            Caustic is sodium hydroxide (NaOH) and this will react with CO2 to produce both sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3); the latter still have some detergent effect although not as great as NaOH.

            The relative amount of the two products is dependent on the conditions , eg. temperature, etc.

            Most automated CIP systems reuse caustic solution many times and only discard when the amount of NaOH drops below a certain level and/or the reaction products are higher than 'spec'. I spent many happy years analysing CIP samples back in my 'lab rat' days

            IF this reaction takes place in a closed vessel with a significant quantity of CO2 present in it and IF the vessel has no form of anti-vac, then it is POSSIBLE the vessel will collapse in as the CO2 reacts, as the external air pressure will be lower than internal pressure.

            Tank collapse is very rare and only tends to occur when caustic is sprayed into a CO2-filled tank through a sprayball. This is because the fine droplets allow a high surface area and thus a fast reaction. As above, collapse also needs this to happen in a tanks where the anti-vac is stuck or which doesn't have an anti-vac valve.

            For a start, if you're pressurising your tank then the fact that your are putting gas in will prevent implosion; furthermore I would suspect that you're using the caustic solution pretty-much immediately, so it's not likely to have fully reacted, therefore what goes into your kegs will be cleaning them.

            If your procedure is cleaning your kegs effectively, such that you're having no problems once they're reused, then clearly it's working.

            You could look at using a plastic transitank for caustic make-up, then either gravity feed into your kegs or pressurise with air. This would get away from any possibility of excessive CO2 compromising the process and would also eliminate any slight chance of someone accidentally using the brite tank for beer before it's been emptied & rinsed.

            Hope that helps!

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            • #7
              cleaning a stainless vessel with caustic in the presence of CO2 will cause beerstone to form on the sides of the vessel. That is why keg cleaning machines use compressed air to blow out whatever is in the dirty keg, then after cleaning and sanitizing, CO2 is introduced into the clean keg.
              Mike Lanzarotta
              Commercial Real Estate Broker
              finding space for breweries in Southern California
              former owner and brewer, Crown City Brewery, Pasadena CA

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              • #8
                Beerstone is calcium oxalate, so will not form simply by cleaning with caustic (sodium hydroxide) itself in the presence of CO2. However if the caustic solution has been made up with hard water, containing calcium salts, then oxalate can form as a result.

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                • #9
                  Originally posted by KWLSD View Post
                  Beerstone is calcium oxalate, so will not form simply by cleaning with caustic (sodium hydroxide) itself in the presence of CO2. However if the caustic solution has been made up with hard water, containing calcium salts, then oxalate can form as a result.
                  KWLSD is correct, I stand corrected. You should always clean with soft water.
                  There is a danger of implosion, I have seen fermenters that were subjected to caustic and CO2 that looked like the Jolly Green Giant squeezed it like a toothpaste tube.
                  Mike Lanzarotta
                  Commercial Real Estate Broker
                  finding space for breweries in Southern California
                  former owner and brewer, Crown City Brewery, Pasadena CA

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                  • #10
                    Originally posted by Fullcourt View Post
                    I have seen fermenters that were subjected to caustic and CO2 that looked like the Jolly Green Giant squeezed it like a toothpaste tube.
                    Absolutely! The most impressive - if impressive is the right word - I ever saw was a 2500-barrel cylindro-conical that had gone. It had a smaller waist than a 1950's burlesque starlet!

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                    • #11
                      I'm looking for some images of FVs (or similar) sucked in due to thermal contraction (no vacuum relief) or chemical reaction such as caustic / CO2, for a training session I am doing.

                      Anyone able to provide me with a couple of suitably catastrophic ones? Unfortunately the last ones I saw were in the days before camera phones and I didn't always have a normal camera to hand.

                      Thanks
                      dick

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                      • #12


                        There is one.
                        Joel Halbleib
                        Partner / Zymurgist
                        Hive and Barrel Meadery
                        6302 Old La Grange Rd
                        Crestwood, KY
                        www.hiveandbarrel.com

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                        • #13
                          Great.

                          Thanks very much. I remember seeing this before - just forgot about it.

                          This will do fine

                          Cheers
                          dick

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