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Question regarding pH for cleaning/sanitizing

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  • Question regarding pH for cleaning/sanitizing

    I am trying to figure out the optimal pH to CIP racking tanks and packaging tanks. My brewery has eight 15bbl racking tanks, two 60bbl racking tanks, one 100bbl racking tank, four 16bbl packaging tanks, and one 60bbl packaging tank. This also applies to sanitizing the plate frame filter. I generally use 10-15 gallons of 185°F-165°F water to CIP and then add 6-8 oz.of acid/caustic. I rinse the tanks with a hose prior to CIP to remove as much yeast, beer, hops, etc. so the solution has a generally clean surface to begin with. I have been taking a pH reading before I cycle the acid/caustic solution in the tank. With the acid solution I have been getting between 1.8 and 2.4 pH reading and with the caustic solution I have been getting between 12.4 and 10.2 pH reading. I then cycle the solution for 15-30 min. and take another pH reading halfway through the cycle. The midpoint pH reading usually holds true to the original reading unless the tank is very dirty to begin with and in that case I generally get a reading for acid solution of 2.2-3.2 and for caustic solution of 11.8-10.0 pH. I also sanitize my plate frame filter with Pall 40x40 pads with a phosphoric acid solution of 15-20 gallons of 100°F water with a minimum pH reading of 2.2, I run the solution through the filter for 15-20 minutes. Are the pH readings I'm getting for my CIP solutions correct to ensure proper cleaning of the tanks? Also is using a phosphoric acid solution with a pH of 2.2 strong enough to sanitize my filter pads?
    Last edited by saintofonge; 01-15-2012, 11:21 AM.
    Jason St.Onge
    Butternuts Beer & Ale
    saintofonge@yahoo.com

  • #2
    The detergent / sterilant supplier should have given you recommended addition / usage rates. Rahter than simply relying on pH, use those and then if you are not getting stuff clean enough, up the temperature or strneght slightly to top end of the range.

    It does sound as though the caustic is being mopped up to some extent by CO2, so if caustic cleaning vessels, you may decide you want to drop the first batch of caustic and use a second batch, or rinse off and use acid for the second batch of cleaning chemical, in which case you can probably go for somewhat lowe strength casutic for the first batch.

    Typical caustic strength is 1 - 2 % w/v, acid 1 - 1.5% w/v - but as I say, use the manufacturer / supplier recommended rates.

    a pH of 2.2 is widely used for phosphoric acid washing of yeast to kill of bacteria, so using it ambient warm (say 15 deg C +) at this pH should kill yeast off pretty quickly as well.

    I would be tempted to use simple hot water - 80 deg C + for 20 minutes for the filter, with no acid, but this may not be possible / advisable for your equipment set up, or possibly because the equipment supplier does not recommend it.
    dick

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    • #3
      Titrate and evacuate

      You might want to contact your chemical supplier to obtain titration kits for the caustic and acid solutions you are using. The titration kits for the particular chemical will tell you more than simple pH will.

      One thing you can use pH for is to test the rinse water to determine when the solution has been rinsed from the tank. This can help reduce wasted water and make sure the chemicals are removed properly.

      For caustic cleaning, we began using a high volume/low speed vacuum (moves a lot of volume but can't pull hard enough to harm an acidentally closed tank) to evacuate the tanks prior to running the caustic. We saw a huge increase in the caustic effectiveness with the post-cleaning cycle titration of the caustic solution dropping only a fraction of what it had been dropping prior to using the vacuum to evacuate the CO2. This increases our cleaning effectiveness as well as reduces our caustic use. It also opens up the possibility of reclaiming caustic. There are a variety of ways to reclaim caustic and return the solution to the correct concentration, but there is also a labor and equipment cost involved so your mileage may vary.

      If you start down that road you may want to consult your chemical supplier and let them know what you are doing and ask for a titration kit that will allow you to test for the spent caustic. The basic caustic titration kits are good for checking starting and ending concentrations, but if you are going to reserve caustic for use in subsequent CIP you want to make sure it is up to snuff for cleaning. The simple titration can be fooled by carbonate buildup in the reservoir. The kits are often provided for use in returnable bottle washing applications - big caustic reservoirs and lots of organic material to eat up your expensive caustic including some acidic beer that may neutralize it as well.

      One easy way to get more out of the caustic one cleaning cylce is to use it to pre-rinse the next tank to get CIP'd.

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      • #4
        We never use pH for determine Caustic or acid CIP solutions, but use mS(Titration) 40mS caustic should be about 2%. and 17mS nitric acid solution should be about 0.5%. Supplier should have all this information.

        We have an in-line metre to check concentration. Much easier then doing titration samples.

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        • #5
          Agree with the general guideline of 2% for caustic, but remember that it will react with any CO2 present to form sodium carbonate which, although it still has certain cleaning capabilities, is much less effective than NaOH.

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