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Neutralising caustic in caustic / acid based KEG washer

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  • Neutralising caustic in caustic / acid based KEG washer

    Hello, after months and months of effort, we finally built a KEG washer for our nanobrewery. It has standard cleaning cycles: water rinse - caustic cycle (NaOH, 3% solution) - water rinse - peracetic acid sanitation (2 % solution) - water rinse - CO2 purge and pressurize.

    Now I'm dealing with problem with neutralising caustic before the peracetic acid cycle. Acid manufacturer told me, that it's absolutely neccesary to neutralize any caustic residue before the acid comes to KEG, otherwise the acid will be quickly killed.
    I'm trying to rinse the caustic with lot of water, but no matter how much I rinse, at the end is still some caustic residue left in the KEG. I disassembled the KEG and rubbed a litmus paper against the spear and the inside of KEG and it's turning still and still slightly blue. Not dramatically, but it's still there.

    Now I have 2 ideas. Just ignore the caustic residue suggesting the amout of caustic left is marginal and continue with acid cycle.

    The secont option that came on my mind is neutralising caustic with CO2. Just quick rinse with water to remove the major quantity of caustic and then purge the air out with CO2. I read that CO2 kills caustic (despite some fierce reaction with large quantities), do you think it can help the problem?

    Many thanks,

  • #2
    Just don't use caustic...

    I'm a fan of NOT using caustic. Use an acid-based detergent instead. Problem solved! Unless you're serving mud, kegs don't really need a caustic cleaning.
    Phillip Kelm--Palau Brewing Company Manager--


    • #3
      We use caustic & a hydrogen peroxide based “booster” (& then water rinse & peracetic) in our ABE 2-head keg-washer. Why would the caustic not simply be rinsed away in the rinse cycle? That’s something I would want to resolve before looking at innovative ways to neutralise the caustic.
      Are your caustic & rinse cycles using low pump/pressure wash/rinses to clean & then rinse the spear itself?
      You can also buy peracetic test strips to check that your peracetic tank is maintained at the right concentration.

      Sent from my iPhone using Tapatalk


      • #4
        ...& Gitchegumee, we regularly fill our kegs with mud, hence choosing caustic [emoji12]
        ...I’ve always used caustic, and in some places I’ve worked we’d periodically change it up to acid. What do you think are the benefits of only using acid? Beerstone removal? Cost? Better clean?

        Sent from my iPhone using Tapatalk


        • #5
          Originally posted by gitchegumee View Post
          I'm a fan of NOT using caustic. Use an acid-based detergent instead
          I am a huge fan of NaOH and KOH and would still recommend acid based detergents on kegs. Cost is a bit better yes, but you are more prone to see beer stone build-up in kegs. NaOH/KOH would technically kill biological organisms faster/better, but the concentrations and acids typically used are still plenty sufficient to be effective at this while providing an advantage to the beer stone.

          Personally I would still use NaOH/KOH on anything that held lacto/pedio/brett. I like a large pH swing for biological concerns.

          As far as neutralization, ignore the chemical salesman and use practical testing methods. Use your litmus paper on the caustic tank (12+ pH), the post rinse (6-8 pH), and the PAA strips on the sanitizer (180+ ppm for me). Check after a few cycles. If your PAA drops super quick, extend the rinse time or add multiple burst rinses.

          If I recall the details, PAA works differently than other acid based sanitizers and can be used effectively to a pH of around 8. Yes 8. Basically it kills by oxidative properties. Your supplier should know this and shouldnÂ’t be suggesting that trace caustic will render PAA ineffective. Ask if they have a chemical engineer instead. Just my 0.02!


          • #6
            A few more reasons for acid...

            NaOH doesn't rinse well without added agents. Acids rinse better and any residuals are more compatible with most sanitizers. So you'll save water. Your dirty kegs have CO2 inside which must be evacuated and replaced with air for use with NaOH. Not so with acid. I use CO2 for washing kegs; no air. It's not much more CO2 use than you'd use with a double evacuation CO2 cycle at the end of cleaning. My DO numbers will typically be less than those using air in their CIP cycles. Some of the detersive acids may also be used without heat, saving energy too. Then there's the aforementioned beerstone issues. For me, it's an easy choice for clear liquids. Might be different if I was packaging mud. Even then, it's very easy to check efficacy of cleaning liquid via titration.
            Phillip Kelm--Palau Brewing Company Manager--


            • #7
              Using a water rinse after the PAA pretty much nullifies any effect the sanitizer has.
              Timm Turrentine

              Terminal Gravity Brewing,
              Enterprise. Oregon.


              • #8
                Hello, thanks for all your comments and suggestions. That´s lot of good ideas to think of.

                First fo all, I ordered PAA test paper and we´ll see, if any caustic neutralisation happens. I measured pH of the PAA solution yesterday - it was 3,8 at the beginning of the cleaning process and 4,4 at the end (after 30 cleaned KEGs and cca 6 hours), but PAA test papers will be more accurate.

                In the second place I contacted salesman from Ecolab. They also recommend acid based detergent for cleaning KEGs (Horolith - phosphoric acid base) and it can be bought for good price. Maybe we could give it a try. I also forgot to mention, that our BYO KEG washer uses cold water for rinse, so I think that can be also problem in combination with hot caustic.

                Thanks a lot!