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  • Brewery cip process questions

    Hi everyone,

    Two questions about CIPs. Looking through the past trending of the daily causticity % of the CIP tanks in my brewery cellar, most were in the 3.5-4.0% range which didn't match up with the Conductivity vs Concentration information that has been supplied by the chemical supplier, so probably the discrepancy comes from flaws in our testing method leading to a greater margin of error than expected and also from the conductivity meters being out of calibration despite them being looked recently by the manufacturer. Given these results, what would your recommendations be on how we verify the causticity of our CIP cellar tanks going forward?

    My other question is about the removal of residual carbon dioxide (CO2) in vessels as a by‐product of fermentation through sterile air flush before CIP. What's the best way of assessing this? Unfortunately, both our Haffmans and the CboxQC portable O2 meter don't read CO2 gasses and I resorted to using a carbon dioxide portable detector.

    Thank you.

  • #2
    If your tanks are relatively small, then positive flushing with sterile air is overkill. Since you are using NaOH based cleaner, I assume you are fully opening the tank for a cold water spray to remove clumped yeast and gross solids. This can be followed by a few burst rinses of hot water to pre-warm the tanks & jackets so that the hot NaOH CIP wash can be done at reasonably high temperatures. If you do this with open manways and other tank penetrations, then the CO2 will be flushed to a sufficient degree. I follow with a warm wash for 30 minutes and my highly polished tanks come out looking great. Another warm water rinse to keep redeposited dirt from drying on the tank interior. Manually wash the manway and all fittings on tank penetrations before acid wash. As for efficacy of NaOH, I would use it until it becomes foamy due to saponification--or until half an hour doesn't clean the tank. If you must measure something, then I like titration techniques. I use titration for many other tests and it's something my lab is set up for all the time. But for me, measuring the %NaOH is secondary to how well it cleans. I can measure how well it cleans by using it, so why measure it? Use it until it loses it's efficacy and then toss it. BTW, you mention cellar tanks; I only acid wash and sanitize BBT between fillings. And then under pressure and cold. Only once maybe 10 fillings will I break it down and thoroughly clean all parts. This works very well for me. Rather minimize oxygen ingress to my BBT than go overkill on hot cycle CIP on a tank that doesn't need it. Best of luck!
    Phillip Kelm--Palau Brewing Company Manager--

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    • #3
      If you are using the conductivity meter to control, and cleaning anything with CO2 residues in, the CO2 (or at least much of it) is mopped up by the caustic to form carbonate or bicarbonate, both of which have much lower conductivities than pure NaOH, AND the buffer the solution, so the probe thinks there is less caustic there than there relly is, and causes more to be dosed in. I have fairly regularly see caustic levels in excess of 5% in FV CIP sets, when it should have been 1.5% max. But unless it goes up over 5%, i wouldn't worry too much. As already said, it is how it cleans, and the level of dissolved and suspended soil in the solution. Throwing the caustic away just because it is a little strong is uneconomic if it cleans and is not re-contaminating.
      dick

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      • #4
        Thanks for all your help. I decided to start cross-checking our conductivity meters with lab titration of the same solution to verify that everything matches up on a weekly basis (operators numbers are too unreliable). A burette is cheap and makes for a great backup and method to calibrate conductivity meters since the titrant is a known concentration. Will also set up a low-level conductivity threshold during CIPs as part of our SOPs, which would set off an investigation should it be exceeded. This happens frequently and is maybe caused by low flow rate, which probably needs to be high to ensure effective mixing of the chemical quickly, or CO2 in a tank being mopped up by the caustic to form carbonate or bicarbonate, both of which have much lower conductivities than pure NaOH like you said Dick, causing more to be dosed in. Still trying to figure the best way to measure CO2 post sterile air flush our 600hl vessels.

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        • #5
          If you have 600 hl brewing vessels then you need to have a serious think about this, as it will cost you a fortune.

          Option 1 is to fit a venturi type CO2 extraction system where the main suction is due to a fast flow of air which then sucks air out of the bottom of the vessel (woth fresh air being drawn in the top of course). If working properly, this should clear your vessels completely in about 20 minutes - no idea a bout air consumption, but has to be less than caustic mop up as this has been installed at at least one multinational brewers sites that I know of.

          Option 2 - go to acid cleaning with caustic pre-wash to waste, as used by many breweries. Works extremely well, but capital cost is high. If your CIP set can't cope with that without major expensive mods. And don't believe some people when they say it only works with sprayballs and not high pressure heads - it does, but you may have to alter the way the custic clean works - see next option

          Option 3 - sacrificial caustic recirculation. Don't bother with a pre-rinse (though you could do if you have excess recovered rinse water) Dump just sufficient dilute caustic into the FV to be able to create a stable recirculation for say 10 minutes, drop to drain and give a quick rinse before giving a "polishing" detergent clean. The caustic you take from the main dilute detergent tank each time will mop up the majority of the CO2, and so the 2nd caustic recirc will not build up high levels of carbonate as it has to be topped up with fresh water and caustic. I have set up this system at 4 breweries larger than yours, and although not perfect, makes a controllable causticity level and keeps the soil loading down so you don't have to drop the detergent tank regularly, say weekly, simply because it is too dirty to be hygienic. This works well with sprayballs and high pressure cleaning heads
          dick

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          • #6
            From my understanding the majority of caustic is converted into Na2CO3 which has a similar conductivity if it stays dissolved. This can obviously result in a lower caustic concentration than would be expected based on the conductivity reading. Source: Brewing Microbiology (3rd ed), Priest, Campbel.

            Another option to consider would be displacing the beer out of the tank with N2 gas. By filling the head space with N2 you can avoid oxidation and have the tank ready for CIP. Nitrogen can be generated onsite from atmospheric air using membrane systems.
            Dave Shapiro
            Technical Training Engineer
            Scandinavian School of Brewing
            Copenhagen, Denmark

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            • #7
              BrewingSchool: From my understanding the majority of caustic is converted into Na2CO3 which has a similar conductivity if it stays dissolved. This can obviously result in a lower caustic concentration than would be expected based on the conductivity reading.

              This is correct!
              Conductivity is not to 100% an indicator for the cleaning effect / % of your caustic. The conductivity remains the same or only changes minimally.
              An easy way to figure out your concentration is a titration for p and m value. PM if you need help with that.

              About the CO2 in the tank.
              We just rinse and open everything. After 1h we start cleaning and never had any problems.

              If you have a bigger tank.
              Look at a blower/fan. We had one in Germany at it worked just great (any size of tank). For a 1200 HL tank 1 1/2 hours. We had CO2 tester ( sorry I forget how they called... IŽll look it up)
              You don't need sterile air ... you open it anyway. Sterile air is expensive!

              This is one reason why its good to used recovered caustic. The "old" caustic reacts with rest CO2 and beer in your fermenter.

              Last edited by TheGermanGuy; 06-08-2020, 12:42 PM.

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