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Thread: DO Pickup From Moving Valve to Valve

  1. #1
    Join Date
    Jul 2012
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    Hopkins, MN, USA
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    18

    DO Pickup From Moving Valve to Valve

    I'm looking for a few opinions and maybe some data on what people are seeing. Say you are moving your from the brite to 2 serving tanks. You setup a transfer hose with a valve on the end, sanitize, and purge all of the sani out with CO2. The serving tank is purged separately. How much DO are you going to pick up by hooking the valve on the transfer line to the valve on the tank. Another way to say that is, how much DO are you picking up from the air trapped in between the two valves. Do you need to purge that, are we being too picky? Do you need to purge it every time you move that valve to a new tank? Thanks for your insight!

  2. #2
    Join Date
    Feb 2014
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    west coast
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    take a butterfly, close it. fill it with water. measure the water volume. double the volume. that's the volume of air on both sides/butterflies. 20% (roughly) should be oxygen.

    divide it by your tank total volume (including headspace) and that's how much oxygen you adding. I'm sure you can google the decimal to ppb figures.

  3. #3
    Join Date
    Aug 2018
    Location
    Hickory, NC
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    18

    DO pickup

    I've had the same thought regarding DO pickup at the butterfly valves and while yes there is a small volume of air trapped in between your valves, by no means can you count that volume of air as dissolved oxygen. Sure, maybe some of that oxygen will dissolve in to your beer but it's a big bubble without a ton of surface area so that already isn't a great situation for gas to go in to solution and secondly remember that there's about a pint of beer in every foot of 1.5" line so depending on what you're doing, that volume of air is being pushed through pretty quickly to a point where you can get it in the headspace and therefore not in your beer. There are some great articles on how DO pickup works through the Hach website that I had to read a few times to understand honestly but it was time well spent. This article I found particularly helpful and it's from a reputable source to boot https://tapintohach.com/tag/o2-in-co2-purity/

  4. #4
    Join Date
    Aug 2010
    Location
    Enterprise, Oregon
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    1,994
    It's easy enough to purge that small amount of air. Just leave the TC clamp between the valves loose, open one valve, tighten clamp when clean fluid flows.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  5. #5
    Join Date
    Jun 2012
    Location
    BEMIDJI, MN
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    142
    +1 to what Timm said. Only we've done it in the other direction...crack the purged and pressurized tank valve while keeping the fitting loose so a bunch of CO2 flows through the fittings, then tighten up and progress with the transfer. When we clean our brites under pressure we set up extra block-and-bleed assemblies so we can purge back from the tank, utilizing the CO2 environment that already exists to back-purge the fittings, rather than purging with a cellar line.

    I agree with the post regarding the large bubble w/ low surface area. While these small practices, when all added together, can certainly reduce DO pickup it is really only quantifiable with a DO meter to evaluate the beer pre and post-transfer.

  6. #6
    Join Date
    Jul 2012
    Location
    Hopkins, MN, USA
    Posts
    18
    Quote Originally Posted by BemidjiBrewing View Post
    +1 to what Timm said. Only we've done it in the other direction...crack the purged and pressurized tank valve while keeping the fitting loose so a bunch of CO2 flows through the fittings, then tighten up and progress with the transfer. When we clean our brites under pressure we set up extra block-and-bleed assemblies so we can purge back from the tank, utilizing the CO2 environment that already exists to back-purge the fittings, rather than purging with a cellar line.

    I agree with the post regarding the large bubble w/ low surface area. While these small practices, when all added together, can certainly reduce DO pickup it is really only quantifiable with a DO meter to evaluate the beer pre and post-transfer.
    Thanks for chiming in everyone. I did the math and if we used a 1.5" ball valve going into 125 gallon tank, assuming all oxygen is dissolved we'd be looking at roughly 12,000 ppb pickup. I know our numbers aren't that high We normally put a tee in between the two ball valves with a 3rd valve on the side to release pressure & purge, I was just trying to gauge where everyone is at with their process. I like just loosening the tri clamp and letting CO2 out, that makes the most sense, doesn't add any additional parts or setup. Thank you for the help and input!

  7. #7
    Join Date
    Jan 2018
    Location
    Malden, Massachusetts, USA
    Posts
    2
    Put a Y or T connection with a butterfly at the fermenter, attach the hose to the brite, open the butterfly at the brite with the CO2 on and then open the butterfly at the Y or T. This will purge the line for you (as long as you shut the butterfly by the fermenter first obviously). I do this, hope it helps.

    Eddie
    Last edited by ED3; 09-06-2019 at 01:54 PM. Reason: clarification

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