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How often do you run nitric acid cycles?

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  • How often do you run nitric acid cycles?

    Hi Folks,

    How often do you run nitric acid cycles (or phosphoric acid) on your FVs and brites? At my previous brewery nitric acid cycles were run after five tank turns for FVs, and after every turn for brites. At my current brewery acid cycles are run after every turn, and I'm wondering if that's really necessary.

    What's the general consensus?

    Cheers,
    Ryan

  • #2
    For me that depends on what you'd call a cycle. I run nitric on both my FV's and Brites after every cleaning. but most cycles I only run for about 5 min with about 1oz acid/15 gal. Ever quarter I run a strong acid cycle to repassivate the stainless.

    I'd also say that your cycles for acid can vary a fair bit based on your water content and beer stone buildup.
    Manuel

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    • #3
      We don't use acid in the brewhouse or wort cooler.

      Passivation is needed when welding has been done or if there are signs of corrosion. It is not necessary to do otherwise. The chrome oxide layer isn't removed that easily under normal conditions.

      In the cold area it is a part of our regular CIP program for the storage tanks and filling machine.

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      • #4
        Some breweries now use predominantly acid cleans for FVs (after a caustic prewash, just sufficient to remove the bulk of the protein / hop krausen ring) saving wasting caustic and co2 in the FV, plus they are cleaned cold, saving shedloads of energy to heat up then recool. Every large brewery I have worked at uses acid cleaning for their BBTs, with perhaps a quarterly caustic wash after degassing. This is because there is little protein to remove in comparison with FVs, but a shed load od CO2 to remove first, or else it denatures the caustic.

        Brewhouse and wort cooler and mains - caustic only
        dick

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        • #5
          MAny schools of thought here. we are a 5K bbl brewery and I see that we run a acid cycle only 1 time a month sometimes that stretches to 6 weeks. I just think that the tank cleans better after a good acid cycle. My tanks are bright and sparkle and I personally think its far cheaper to run some acid then to dump a batch of beer. I am sure there is some grad of a big school that can provide some scientific evidence on this but I am just a old school brewer
          Mike Eme
          Brewmaster

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          • #6
            We run an acid rinse on each tank cip, 1 oz per 10 gal for 5-10 minutes. Keeps the beerstone down, particularly on the hard to reach spots like the roof of the sample ports, racking arm port, etc.. Save some caustic from the cip to neutralize the pH before that wash hits the drain.

            Anyone else out there doing the 'reverse' passivation? Read an article by Birko about a different method to passivate. Rather than caustic/rinse/acid/air dry for a day they suggested acid/no rinse/sodium metasilicate (PBW)/rinse and you're good to go. Idea is that this eliminates using caustic, and the silicates react immediately with the acid to form a sort of glass layer that protects the already reasonably passivated stainless. Came in handy when we recently had to get two new tanks online like yesterday and didn't have time for it to air dry. Did the Reverse method, immediately sanitized, wort went right in. So far seems nice and shiny in there still.
            Russell Everett
            Co-Founder / Head Brewer
            Bainbridge Island Brewing
            Bainbridge Island, WA

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            • #7
              I think the caustic/rinse/acid/air dry passivation cycles have been firmly debunked here on ProBrewer a few times in favor of instead caustic/rinse/acid/rinse/air dry. For instance, here is Loeffler's recommended protocol:

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              Or alternatively, if you read the ASTM standards, A380 and A967, both say something to the effect, "Immediately after removal of the passivating solution, parts should be thoroughly rinsed".

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              • #8
                It is necessary to perform an alkaline cleaning cycle before your passivation. New tanks will have rolling oils, welding fluxes, grinding and polishing grit, boot prints, hand prints, bird crap, road grim, and the like. This should be cleaned first before your passivation.

                The concentration of Nitric Acid is ultimately what contributes to passivation. Our recommendation is 4-6% concentration Nitric acid. For the LERACID K-MS 10 mentioned in our passivation instructions posted by AnthonyB, this is a 10-15% by volume solution of LERACID K-MS 10. For other products, this may be 50% by volume or even an undiluted concentrate. Be wary of chemical vendors that will sell non-Nitric Acids or products that are lower in Nitric Acid than other acids. We recommend an ambient temperature passivation, but will sometimes heat the acid to deal with problematic stainless steel, usually non-reputable vendors West of the Pacific Ocean. This solution should be recirculated for 1-2 hours if possible, and may be recirculated longer if required. However, once the recirculation is stopped, the acid should be moved from the vessel and the vessel should be rinsed until free of acidity. Do not allow acid to dry in your tanks. This is recommended by some of our competitors with devastatingly destructive results to stainless steel. Once the acid is rinsed from the tanks, the tanks should be visually inspected and can be considered passivated. It is not necessary to silicate-line the insides of your tanks if they have been properly passivated, and we have found this process to create a host of other problems.
                Loeffler Chemical Corporation
                (404) 629-0999
                800-769-5020 (US & Canada only)
                www.loefflerchemical.com

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