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Thread: What gasket material for PAA environment and Caustic environment?

  1. #1
    Join Date
    Jun 2011
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    176

    What gasket material for PAA environment and Caustic environment?

    Right now our keg washer has all viton gaskets in its pumps.

    We use PAA on our sanitize side and are about to switch to caustic on the washing side (from an acid based cleaner).

    I would like to order rebuild kits with the right gasket material for the job.

    From what I understand - EPDM is the best for PAA - but I'm finding less info for caustic.

    Thanks!

    Brian

  2. #2
    Join Date
    Jul 2009
    Location
    Austin, TX
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    For heat and most chemicals, including caustic, EPDM is hard to beat.
    Especially while bumping EPMD.

  3. #3
    Join Date
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    I'd stick to Viton. I've worked in a couple of large companies where we changed from EPDM to Viton, never the other way round. Viton is far more resistant to PAA than EPDM. Not sure about caustic, but Viton seals lasted for years in major breweries where you are brewing and cleaning 27/7, using caustic, acid and PAA, and H2O2 in some brewhouse and dosing pump cleans.
    dick

  4. #4
    Join Date
    Aug 2010
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    Enterprise, Oregon
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    Viton is about as good as it gets. I'd consider EPDM to be a step down from Viton. Buna does not like PAA--we've had to replace a lot of Buna gaskets since switching to PAA for our sanitizing soak.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  5. #5
    Join Date
    Oct 2013
    Location
    Dallas, Bangalore and soon Goa
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    I would agree with most that Viton is a perfectly acceptable material for the majority of brewery uses, but would counter the common belief that EPDM is less resistant to PAA (and other commonly used chemicals in the brewery).

    When you look at chemical compatibility charts, often EPDM will be rated more satisfactory for Acetic acids and Peracetic acid over Viton. When comparing Hydrogen Peroxide Viton is great even at 90% concentrations, where as EPDM compatibility degrades with concentration. It (EPDM) is still considered the highest level of resistance at "normal" brewery type concentrations (less than 90%). When you look at Sodium Hydroxide, or Potassium Hydroxide, the EPDM has a higher resistance value. As far as heat resistance Viton will have a good working range between -20*C to 210*C, while EPDM is around -45*C to 145*C, so Viton gets a slight edge, but both are within expected needs in the breweries I have worked at.

    In my mind, the best thing Viton has going for it (and just to double clarify, I think it is a good option in general) is its higher resistance to certain oils, fuels and hydrocarbons (not things I commonly use in the brewery). EPDM is often a slight bit cheaper and offers a wider range of resistance (according to my research). My experience tells me both have been sufficient for the general needs of the brewery.

    Again, in my experience, the EPDM gaskets have worked well for me and I have seen a few HX daily cleaned with caustic and packed with PAA for many years (some as long as seven years), without severe degradation of the gaskets, so I place preference on EPDM myself. Just ordered a new HX for a new production facility as well and went with EPDM for these reasons, fwiw.

    Here is a link to a good chemical resistance reference, but there are many others out there as well.
    http://mykin.com/rubber-chemical-resistance-chart

  6. #6
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    Great link - thanks
    dick

  7. #7
    Join Date
    Aug 2010
    Location
    Enterprise, Oregon
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    I started numbering and tracking our butterfly-valve seats over a year ago when we switched from using Iodaphor to PAA for our soak. We've had several different materials for our seats, and, from my records, silicone has won hands down for durability. EPDM and Buna did the poorest, with the Buna seats lasting as little as a month. Of course, BF valve seats get a very different kind of wear than a static seal like a TC gasket, where EPDM has performed very well for us.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  8. #8
    Join Date
    Oct 2013
    Location
    Dallas, Bangalore and soon Goa
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    Quote Originally Posted by TGTimm View Post
    I started numbering and tracking our butterfly-valve seats over a year ago when we switched from using Iodaphor to PAA for our soak. We've had several different materials for our seats, and, from my records, silicone has won hands down for durability. EPDM and Buna did the poorest, with the Buna seats lasting as little as a month. Of course, BF valve seats get a very different kind of wear than a static seal like a TC gasket, where EPDM has performed very well for us.
    I have found Silicone seats to hold up no better than EPDM, and technically Silicone is less resistant to Peracetic. I think the durometer value or hardness of the material tends to matter more in valves than the actual material between these two (EPDM and Silicone). Case in point, my Silicone valves have softer seals that tend to rip before the material itself fails. My EPDM's tend to be harder to turn the handles. Both have occasionally leaked ever so slightly, but both are usually fixed by a tightening of the shell. I have never had any failures in a year, or even two, with these materials.

    Name:  Torn Gasket.jpg
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    I always avoid Buna due to its short lifespan in the brewery conditions.

  9. #9
    Join Date
    Aug 2010
    Location
    Enterprise, Oregon
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    I started numbering and tracking our BF valves in Nov. '15, when we had some problems with new valve seats. It was meant as a tool to evaluate the various options for seat materials and manufacturers.

    I currently have 50 numbered valves (40 1 1/2", 8 2", 2 3") on my list. I put the numbers on the valves when they come into my shop for service. Of four EPDM seats that have failed and been replaced, one died in 9 months, two in three, and one in four. Of the silicone seats I've replaced, all three were manufacturing defects, since cured.

    Some of these Tassalini vales w/silicone seats have been in use for at least twenty years before their first replacement, but the switch to PAA seems to accelerating the wear on the silicone seats. They still outperform EPDM for our brewery use.

    Unfortunately, this is a Word doc, not an Excel spreadsheet.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

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