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  • Dissolved Oxygen levels/chart

    As we are beginning to monitor our DO levels (only took 13 years...) I was looking for a chart looking into the threashhold levels for packaging bottles/cans.

    1) PPB levels in beer at packaging. Shaking vs not shaking.
    2) PPB levels in beer at various intervals after packaging.
    3) headspace air.
    Is is measured as a percent?

    Anyone have a quick link to a protocol out there?

    We just did some monitoring and it sounds like we have lots of work to do...

    Packaging day--
    Head space O2 (as a percent) after packaging (no shaking)--~4.4%
    Beer DO levels at packaging--65 PPB
    Head space O2 (as a percent) after 10 minutes of moderate shaking --2.2%
    Beer DO levels in beer after shaking --183 PPB

    Next day--
    Head space O2 (as a percent) after packaging (no shaking)--~3.0%
    Beer DO levels at packaging--200 PPB
    Head space O2 (as a percent) after 10 minutes of moderate shaking --1.7%
    Beer DO levels in beer after shaking --303 PPB

    Next Day
    Head space O2 (as a percent) after packaging (no shaking)--~2.4%
    Beer DO levels at packaging--203 PPB
    Head space O2 (as a percent) after 10 minutes of moderate shaking --2.0%
    Beer DO levels in beer after shaking --320 PPB


    So at day three- things look like they are starting to level out. Next is to monitor beer in tanks, just before filter, just after filter, in the bright tank, before diaphram pump, after diaphram pump, in filler bowl on bottling day. All of this will be in PPB and we can see where we are picking up these airs. The next thing is to figure out how to solve it bearing in mind a systematic plan and a budget.

  • #2
    Diaphragm Pump? Never used one on product. Maybe that's the problem.
    Jason Raimondi
    Anderson Valley Brewing

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    • #3
      I have no issues using a centrifugal pump as well--however it was always my impression that when these types of pumps have to be choked back, you can create lots of turbulence which is bad for the beer. Many of these types of pumps also will allow more air to seep through due to the rotary seal...vs clamped gasket material in the diaphram parts of the pump guts...

      either way, this thread isn't so much to be started on which pump is better or worse, it is targeted to be conversing soley about air and specifically O2 levels in beer and the bottle head space. Do you have any data on those points of which I am hoping to obtain?

      Cheers
      DEREK

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      • #4
        Make sure to tighten the crap out of all your tri-clamps, especially before the pump. We have physically watched the levels drop as we torque down on the clamps. Just because they are not leaking fluid doesn't mean that the suction of the pump isnt drawing air in.

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        • #5
          I am always a believer that overtightening of clamps is bad--it "squishes" the gasket inside a pipe, hence not creating a smooth pipe to allow for lamaner flow. Instead it creates eddys in the line that can harbor bacteria. Lastly it degrades the substance of the gasket.

          Irregardless, just like the previous thread, I am actually looking for values tha people see and values that we should strive for--not the techniques used to help lower them! Do you ahve any of those values?

          DEREK

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          • #6
            Derek,

            Your initial dissolved figures immediately after bottling (no shaking) suggest to me that your beer itself (and, so, the process up to bottling) is not problematic. 65ppb DO is not the sort of level that will cause major oxidation/staling issues in itself; you could aim for lower, but for all-but the most lightly-flavoured beers, this isn't a killer level. Without shaking, this is a decent guide as to the DO level in your beer pre-filler, ie. in the filler bowl itself.

            NB: When you say "Beer DO levels at packaging" can you just confirm for me that this is the DO measurement in the bottle, immediately after packaging?

            As you are seeing, over time, with or without shaking, the headspace O2 is dissolving into your beer and those numbers look typical of the effect. Hence the headspace figure drops and the dissolved level rises. This will continue until the levels equilibrate, courtesy of Dalton's Law, if you'd like the physics!

            To give you a rough guide, a DO meter set up for liquid analysis will read around 8ppm in air, ie. exposed to 20% gaseous O2. If you expose that meter to gas that has around 2.5% oxygen - like your headspace at equilibrium - it will read around 200ppb, which is what you're seeing as dissolved O2.

            The problem looks to be with your filler. The figure you're seeing of 4.4% in headspace immediately after fill and without shaking is a good estimate of the amount of O2 in your bottles pre-fill. As air is ~20% O2, you're still being left with nearly a quarter of the O2 remaining after the bottle has been purged. I'm assuming here your bottler has some form of pre-fill purge, of course.

            My initial course of action would, thus, be to look at the filling operation itself and ways to reduce the amount of O2 remaining in the bottles before they're filled.

            If you can just halve the amount remaining, you can reasonably expect to carry that reduction through, pro rata, to filled/equilibrated bottles, so should then have final dissolved levels closer to 100-150ppb, which would be not unreasonable as a 'first target'.

            To put some target maximum numbers on things:

            Pre-fill DO: around 50ppb
            Equilibrated DO after fill (ie. shaken): around 100ppb
            Total in-pack oxygen: around 250ppb*

            *Total in-pack oxygen, or TPO, is usually measured as ppb. As a guide, I tend to work of the basis that a 'good' TPO (based on the equilibrated in-pack DO) is no more than 2.5 x dissolved, so:

            A bottle with a shaken DO of 40ppb should have a TPO not exceeding 100ppb.

            This is based on a headspace that is ~5% of total package volume.

            Hope that helps!
            Last edited by TL Services; 08-18-2012, 03:05 AM.

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            • #7
              Now THAT was some good advice.

              THANK YOU!

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              • #8
                And with the system that we have there is a O2 sensor in the head space of the bottle and an O2 sensor contacting the beer istelf. So the readings of 4.4% o2 headspace and the 65 ppb at packaging...this means that the beers were immediately taken off the line after being capped, and then read.

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                • #9
                  Glad to help - keep us updated on progress.

                  In a former life I spent many years armed with a DO meter and dodging around brewery plant chasing oxygen level reduction - back then meters were big, unwieldy items and we thought getting under 1ppm (yep, ONE PPM, not a typo...) was an achievement

                  Hopefully I learned something then, so it's good to keep it fresh now I'm on the other side of the fence - servicing, repairing and selling meters for a living!

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                  • #10
                    Hmm.. both your prefiller DO and post-fill DO look high. We bought a DO meter at the same time as when we purchased a new filler, and I was shocked at how much improvement we were able to make on DO before the filler, once we started checking it throughout the system. We made a lot of changes to our filtering and BBT cleaning processes that improved our DO readings as much as from going to a double-pre-evac filler.

                    One place to look at immediately is before and after the filler pump. Loose fittings and seals may not leak beer but will be leaking air in. We had a seal on our centrifugal pump that was not leaking beer, and that when we pulled it out after high DO readings after the pump, looked perfectly fine. But when we replaced the seal with a new one, the DO readings went back down to normal.

                    Hach has some excellent information on typical DO levels in a brewery somewhere on their website.
                    Linus Hall
                    Yazoo Brewing
                    Nashville, TN
                    [url]www.yazoobrew.com[/url]

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                    • #11
                      Pump seals - indeed anywhere there's a seal in the process stream - are notorious for leaking air in without signs of beer coming out. Usually this occurs on the inlet, low pressure, side as the pressure gradient is in the right direction.

                      Having a portable DO2 meter is vital (and I'm not just saying this as we sell them - but from 25 years experience as a user) to identify the sources of DO2 pick-up.

                      Sometimes you get lucky and find a big hit, but very often it's just incremental improvement in technique, running the process and taking care that makes the difference.

                      There is evidence that sub-30ppb levels in final product are not noticeably detrimental to taste/ageing for most beers that have a degree of flavour.

                      What is critical is ensuring DO2 levels are maintained at low levels throughout the post-fermentation process and this is sometimes a point that gets forgotten in the drive for lower packaged levels; after all there's no point in having single-digit DO2 in bright tank if the beer's already been oxidised to h*ll beforehand...the damage is already done!

                      Just to be clear, the figures I suggested (above) are the sort of maximum figures for an initial set-up. There's always a drive to lower DO2 but you have to start somewhere and Derek asked for some guideline numbers

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                      • #12
                        Scrubbing beer

                        @ KWLSD: I am having a conversation about DO with my brewer. You mention in the previous post that once it is in there, the beer is already headed downhill. Is it acceptable practice to "scrub" the beer with Co2 to drop DO levels in the BBT before packaging? Is that doing more harm than good? Obviously the right thing to do is to get it low in the first place, but if it makes it through, is there any other acceptable practice to lower it?

                        BTW, we are picking the DO up during filtration. Levels are low in the fermenter.

                        Thanks for any info!

                        Matt

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                        • #13
                          Matt,

                          There's no problem gas washing to reduce DO, but only as a last resort; much better to find the source of the increase and address that

                          Usual practice is to use nitrogen rather than CO2, then re-carbonate to specification, rather than gas wash with CO2.

                          As regards high DO levels before final product; many times in the past I have seen beer that's high DO in maturation tank (ie. chilled, pre-filter) being left until the level has dropped into spec. All this means is the oxidation reaction is happening before it's filtered...

                          Some years ago (late 80's) I worked for a big UK brewer when Australian beers were uber-popular over here. One in particular was very sensitive to high DO so not only did we measure it with DO meters, we also had a lab analysis that allowed us to quantify the level of oxidation that had already occurred once the product reach bright tank.

                          If you're picking up DO through filtration, the usual suspects are pumps, pipework, leaks into the filter, etc.

                          Good practices that I can also suggest (some may not be applicable to your situation, but better to have as much info as possible!):

                          - If you use water to make up filter powder/bodyfeed, use dearated;
                          - Where possible, pack mains/filter with dearated water before running beer, especially if it's a fresh filter;
                          - Analyse at as many points as possible across the filter set-up, to try to narrow-down where it's coming from.

                          That's certainly not exhaustive and I'm sure there'll be other suggestions that I've missed or plain not thought about...

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                          • #14
                            Handy little chart

                            Hi guys,

                            Taking the GCB tomorrow, and they have this nifty chart. Hope it helps!
                            Btw if anyone has a similar chart with flow rates from a bbt, much appreciated 😀Click image for larger version

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                            • #15
                              chart

                              Originally posted by Lizzbeth View Post
                              Hi guys,

                              Taking the GCB tomorrow, and they have this nifty chart. Hope it helps!
                              Btw if anyone has a similar chart with flow rates from a bbt, much appreciated ��[ATTACH]61856[/ATTACH]
                              This is nice, where did you find this? Can you post more pictures of this section please?

                              Thanks,

                              Dylan

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