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  • 1.  Strange coloration in fermenter

    Posted 02-01-2023 08:50
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    Hello,

    We are starting to get this coloration in two of our fermenters in the same area around the racking port. I have contacted the manufacturer and they aren't helping. We have tried pretty much everything during CIP to remove it and nothing has worked. 

    Thanks,
    Zach




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    Zachary Gordon
    Old Thunder Brewing
    Pittsburgh PA
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  • 2.  RE: Strange coloration in fermenter

    Posted 02-01-2023 12:19
    Hi Zachary,
    That looks like typical heat stain. Pretty funny that "stainless" can stain, but it does. 
    I think a long, strong passivation might take care of it, but it really isn't doing anyhing. Do you really need to remove it?

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    Greg Marshall
    Full Sail Brewing Co
    Madras OR
    (503) 560-5209
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    Original Message


  • 3.  RE: Strange coloration in fermenter

    Posted 02-02-2023 11:47

    Kyle,

    Its hard to tell from a picture, but its likely one of two things:  1.  Protein.  Protein starts with a purplish hue and then becomes brown as it gets thicker.  An oxidizer like chlorine as mentioned or hydrogen peroxide in the caustic is best to remove.  Sometimes there is a CIP shadow below the manway or racking arm.  2.  Oxidation from an oxidizing chemical.  Is this directly below the manway where you poor chemicals in for CIP?  If so, it may be that the fermenter was hot from rinsing and chemicals in concentrate contacted this area?  Hydrogen peroxide is the usual culprit.  Chemical attack will darken as there is more attack. 

     

    Mike Willis

    Northern California Territory Manager

    Certified Water Technologist

    Chemco Products Company

    1992 Rockefeller Dr. #800

    Ceres, CA 95307

    Office: 1.209.556.1222 x277

    Cell: 925.642.6901

    40@chemcoprod.com

    www.chemcoprod.com

     

     

    Leading the world to a cleaner safer place through unparalleled customer service one client at a time.

     

     




    Original Message


  • 4.  RE: Strange coloration in fermenter

    Posted 02-01-2023 20:28
    Hi Zachary,
    Looks like a rainbow stain that I've seen in some of our fermenters from time to time.   We called our tank manufacturer many years ago and asked about these stains and they said that some stainless alloys can pick up this discoloration and it really doesn't hurt anything, I don't remember if they told me what causes it.  But if it bothers you like it did us, run a 2% caustic solution with a maximum of 1 pint of bleach in a 3 bbl batch of water (i.e. not much bleach) and it will remove it quickly.   Don't run the cycle any longer than 15-20 minutes and rinse really well, any chlorinated water that dries on the stainless will damage it permanently.   If that amount of bleach doesn't work then you might have something else going on or you might need to run another cycle with a slightly higher level of bleach.   We found we didn't have to run the cycle ever again, but we were told some people have to run it every few years.

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    Curtis Holmes
    Alaskan Brewing Co
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    Original Message


  • 5.  RE: Strange coloration in fermenter

    Posted 02-10-2023 16:49

    Dear Zachary:

    Based on the various stains and wipes visible in your picture, there may be a few different things going on here. The rainbow discoloration could be rouging, which can have several causes. The entire tank appears to have a deposit inside it. Since there are streak marks from investigating the rainbow color, my guess would be organic since this generally does not happen with inorganic deposits. Rouging can occur when heat and air contact the stainless steel or when halogens like chlorides are present at elevated temperatures. 

    I would recommend first running a caustic in combination with an oxidizer through this tank first and remove the other deposits that are present.  If you are using a Hydrogen Peroxide based additives, try to get the temperature of the caustic solution to or above 130 F.  Circulate for 30 - 45 minutes and rinse.  Check the tank.  Repeat if necessary (you should see improvement during the first cycle).

    If the rainbow color is still present, try running a strong passivation once the tank is clean and free of deposits. Rinse the Nitric Acid and check the discoloration.  Again, repeat if necessary. 

    Cheers,   

         



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    Dirk Loeffler
    Loeffler Hygiene & Safety Solutions
    (404) 229-7583
    loeffler.dirk@loefflerhygiene.com
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    Original Message


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