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Thread: Packing Heat Exchanger With PAA - Recommendations

  1. #1
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    Packing Heat Exchanger With PAA - Recommendations

    My SOP for the brewhouse HX is to run a caustic cycle after brewing and then run a short PAA cycle (~0.3% solution) and leave packed until next use. Our capacity allows for longer downtime now and I'm wondering if I need to be doing more between brews. Any ideas on how long PAA is supposedly viable if packed in the HX? Should I be worried about my HX gaskets degrading?
    Last edited by Peters; 01-09-2020 at 10:56 AM.

  2. #2
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    Quote Originally Posted by Peters View Post
    My SOP for the brewhouse HX is to run a caustic cycle after brewing and then run a short PAA cycle (~0.3% solution) and leave packed until next use. Our capacity allows for longer downtime now and I'm wondering if I need to be doing more between brews. Any ideas on how long PAA is supposedly viable if packed in the HX? Should I be worried about my HX gaskets degrading?
    First, I would always recommend you contact the HX manufacturer for their best practices recommendation. Generally, it is recommended to run your CIP solution in the reverse direction of normal flow at 150% of normal operating flow rates. I often run my solution in both directions for a period of time, simply because I can easily. The typical cleaning solution range might be around 0.5-2% by volume of liquid caustic product depending on temperature and efficacy. Looking for a pH of 12+ at the end of cycle. Flush until pH neutral. Occasionally I will pack my HX with caustic for a 12hr period as a "deep soak".

    Packing with PAA is my preferred method, and I have not seen it cause issues over prolonged periods on EPDM gaskets. You can verify the chemical compatibility of your gasket material with PAA on many independent websites. You will find it has a B or better rating for peracetic acid and hydrogen peroxide independently at the strength you will find most suppliers offering. By the time you dilute that 0.3% PAA (with the 24% H2O2 it likely contains included) to the proper sanitation strength, you will find that you are well below the threshold of concern for compatibility. Your strength for sanitizing should probably be a minimum of about 150ppm depending on the exact product you are using. I like LaMotte strips and just check for 180ppm+

    The PAA is extremely effective at killing over prolonged periods (even at very low concentrations) and that is why I prefer to pack myself. I have seen studies showing that while degradation of PAA can occur quite quickly, the addition of hydrogen peroxide helps improve stability drastically (this is part of the reason they blend the H2O2 and PAA). In documented literature I have somewhere, I have seen effective capacity beyond one month in normal circumstances. With that said, I always re-run a sani loop if my equipment has been sitting more than a couple days, and replace my soak and sprayers every week or so.

    The best objective way to verify your results is through ATP or environmental swab and incubation. You should also run a de-mineralization cycle periodically. Usually a nitric/phos blend will be the best option, but this should never be left packed for long times. I tend to run one about every trimester or so.

  3. #3
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    Very useful, thanks for the info UnFermentable

  4. #4
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    I run caustic both forward and then reversed, rinse like hell and then heat sterilize with water and leave it packed till next use.

  5. #5
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    I know it is semantics, but you are not heat sterilizing with water unless your water is at 121*C (250*F) and you apply it for a minimum of about 15 mins. You are likely pasteurizing only, which does not actually come close to sterilization. Pasteurization is intended to reduce microbial activity of food born pathogens, but not meant to denature all living organisms (sterilization). CDC is a great resource if you care to know more.

    In brewing we are primarily concerned with "Disinfection", which differs from both Sterilization and Pasteurization. Disinfection, like pasteurization, does not account for destroying spores, which is included in the definition of Sterilization. Some "Disinfectants" are capable of sterilization when used at appropriate concentrations and meet minimum contact times. PAA is effective against spores at high concentrations (275+ ppm), but also has a wide ranging ability to kill algae, bacteria, and mold as well as help breakdown bio-films. Prolonged periods often result in drastic log reductions depending on the exact organism.

    PAA is absolutely 100% better than hot water, especially when letting something sit for extended periods, however that is not to say that hot water cannot provide a sufficient disinfection for your needs.

    Oh, and if you want to save some water get some litmus paper and check for pH neutral when rinsing. You can "feel" the hardness of the water when you've been doing it a while, but an objective measure is always best.

  6. #6
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    Both Muller and Thermaline recommend NOT packing with CIP fluids, from a health of the equipment standpoint of course.
    Brewmaster, Minocqua Brewing Company
    tbriggs@minocquabrewingcompany.com
    "Your results may vary"

  7. #7
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    Excellent Advice Ted....

    Quote Originally Posted by Ted Briggs View Post
    Both Muller and Thermaline recommend NOT packing with CIP fluids, from a health of the equipment standpoint of course.
    Spot on Ted.
    The thing seems to be a constant attempt to reinvent the " wheel " and also trying to make Brewing more science than art which is a colossal mistake.
    Warren Turner
    Industrial Engineering Technician
    HVACR-Electrical Systems Specialist
    Moab Brewery
    " No Cell Phone Zone."

  8. #8
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    Quote Originally Posted by Ted Briggs View Post
    Both Muller and Thermaline recommend NOT packing with CIP fluids, from a health of the equipment standpoint of course.
    This is why it is super important to understand chemical compatibility. Stainless Steel (304 or 316 of our usual "food" or "medical" grades), EPDM, & Viton are fine for KOH, NaOH, and PAA at our general working concentrations and contact times. This is why chemical compatibility is graded with a letter, which these specifically get a B or higher. That lets you know it is in fact safe to use, and judge a potential lifespan based on the conditions. I like science, it's my friend.

    Of course prolonged contact time will reduce effective lifespan, but after having physically seen HX's that have been packed with 200ppm PAA daily for over 10 years and not seeing a degradation of seals (EPDM), and no corrosion or buildup on plates, I have no concerns myself. When combined with the low effective rate of PAA (as little as 10ppm) and long term log reductions, it makes sense to add a small amount of PAA even if you are not looking to achieve a 200+ppm sporicidal concentration.

    YMMV. I trust the hard sciences as it protected my life when working industrial scientific research. I had processes where there was an important distinction between pasteurizing and sterilization, and even in the methods used to achieve both. If I have to replace seals every 25-30 years, I'm okay with that. Iodine will pit your stainless, and higher temperatures and concentrations with increase the rate of reaction. Don't use a procedure (or not) because someone else does (or doesn't). Understand what you are trying to accomplish and engineer and verify your results to suit your exact need. Or you know, ditch the lab and just splash some paint on the canvas. That can make some pretty good beer, occasionally. I get the whole "I'm an artist" thing, nothing wrong with that, but packing with PAA is nothing new, it has been used in the industry for decades. Its certainly not "re-inventing the wheel". I don't need a microscope to make award winning beer, but I still use it when its available!

  9. #9
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    Quote Originally Posted by Starcat View Post
    Spot on Ted.
    The thing seems to be a constant attempt to reinvent the " wheel " and also trying to make Brewing more science than art which is a colossal mistake.
    What is your guys procedure?

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