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Thread: Purging BBT's

  1. #1
    Join Date
    Jun 2012
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    153

    Purging BBT's

    Before transferring beer from FV's to BBT's, how much co2 do you guys use to purge? As co2 is heavier than atmosphere, I am assuming that I could get by with just a thick layer of co2 in the bbt and then fill from the bottom. At least that's what I've always done as a homebrewer when racking to corny kegs and never had any oxidation issues. Would the same thing work in a bbt?

  2. #2
    Join Date
    Mar 2013
    Location
    Clive, IA
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    There are a few threads on here discussing this.

    I believe the official "best" way to do it is to fill the BBT with de-oxygenated, sanitized water and then push it out with CO2.

    That is not feasible for many breweries for a variety of reasons, so the conventional wisdom that most folks, it seems, go by is to fill to 15PSI from the bottom and purge slowly from the CIP arm twice. Yes, CO2 is heavier than air, but it also takes a long while to settle out and will blend with air as it's introduced (think vinaigrette in a bottle). By filling the tank twice, even assuming you are getting a pure blend of CO2 and air, you are diluting the O2 to a level where it probably won't have much effect.

    If you're not packaging for shelf stability, (i.e. you expect to sell it all in a pretty reasonable amount of time), that's probably sufficient. I would be hesitant to just push a little CO2 in and hope for the best.

  3. #3
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    Jun 2012
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    Thanks dave

  4. #4
    Join Date
    Nov 2009
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    4

    Low and Slow

    We've been in search of the best purge process for some time now. After discussing with other brewers how they are most successful, and after doing a good bit of testing ourselves, we've found that low pressure CO2 in the bottom of your tank and an open blow off arm works best. We have a DO meter we hook up to measure the oxygen levels. Once we hit our acceptable DO in gas we feel comfortable racking. Each tank seems to act differently but a good number to go by in our estimation is about 4psi CO2 feed for approximately 45 minutes to an hour. I'll be honest sometimes it takes longer and sometimes it goes faster than that. Without a meter it's just guessing. My opinion is if you use higher pressure and restrict outflow you cause more turbulence and mixing of O2 and CO2. Hope this helps.

  5. #5
    Join Date
    Nov 2008
    Location
    Leadville, CO
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    Our SOP is to pressurize to 15 psi from the bottom, then bleed down to 5 psi from the top of the brite. For a tank that's been CIP'ed under pressure, one of these purges is enough to get our product DO under 50 ppb, and generally under 20 ppb, which is the target. If the tank's been opened, 4-5 purges are necessary to get those DO levels.

  6. #6
    Join Date
    Jun 2012
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    Quote Originally Posted by a10t2 View Post
    Our SOP is to pressurize to 15 psi from the bottom, then bleed down to 5 psi from the top of the brite. For a tank that's been CIP'ed under pressure, one of these purges is enough to get our product DO under 50 ppb, and generally under 20 ppb, which is the target. If the tank's been opened, 4-5 purges are necessary to get those DO levels.
    Not to get off topic, but why do you cip under pressure?

    ETA-nevermind, I just found this thread:

    http://discussions.probrewer.com/sho...under-pressure
    Last edited by d_striker; 03-12-2014 at 08:28 AM.

  7. #7
    Join Date
    Jun 2012
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    153
    Quote Originally Posted by jailhousebrewer View Post
    We've been in search of the best purge process for some time now. After discussing with other brewers how they are most successful, and after doing a good bit of testing ourselves, we've found that low pressure CO2 in the bottom of your tank and an open blow off arm works best. We have a DO meter we hook up to measure the oxygen levels. Once we hit our acceptable DO in gas we feel comfortable racking. Each tank seems to act differently but a good number to go by in our estimation is about 4psi CO2 feed for approximately 45 minutes to an hour. I'll be honest sometimes it takes longer and sometimes it goes faster than that. Without a meter it's just guessing. My opinion is if you use higher pressure and restrict outflow you cause more turbulence and mixing of O2 and CO2. Hope this helps.
    Thanks JHB. This process seems to work great for us.

  8. #8
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    Sep 2008
    Location
    Fawn Grove, PA, USA
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    548

    What Meter?

    Quote Originally Posted by jailhousebrewer View Post
    We've been in search of the best purge process for some time now. After discussing with other brewers how they are most successful, and after doing a good bit of testing ourselves, we've found that low pressure CO2 in the bottom of your tank and an open blow off arm works best. We have a DO meter we hook up to measure the oxygen levels. Once we hit our acceptable DO in gas we feel comfortable racking. Each tank seems to act differently but a good number to go by in our estimation is about 4psi CO2 feed for approximately 45 minutes to an hour. I'll be honest sometimes it takes longer and sometimes it goes faster than that. Without a meter it's just guessing. My opinion is if you use higher pressure and restrict outflow you cause more turbulence and mixing of O2 and CO2. Hope this helps.
    What meter are you guys using, I assume your measuring on the outlet port? New to Do meters here, looking for insight..

    Thanks

  9. #9
    Join Date
    Mar 2014
    Location
    Minneapolis, MN
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    12
    We use similar techniques vs others on this thread with a bit of a twist. Firstly we clean our BBTs with an acid cleaner instead of caustic so that we don't have to open the BBT and can maintain a high level of residual CO2 inside the tank, which generally means using less CO2 to purge later. THen once the BBT has been cleaned/rinsed/and sanitized (30-50 min cycles for each of the cleaning and sanitizing loops) we push CO2 in through the bottom at around 15psi while allowing off gassing through the CO2 "entry" valve on the CIP arm, which in turn is connected to our DO meter.

    It used to take 45+ minutes to get the DO reading under 500ppb (which is considered our absolute minimum...we've compared this result to the Zahm CO2 "crackpipe" tool and found that it's over 95% CO2 at this level). However lately we've been allowing the BBT to gradually approach 15psi head pressure, then open the PRV arm completely and completely blow down the tank to 1-3PSI. Once the blowdown is complete the DO reading almost immediately falls significantly. Usually only takes 1-2 blowdowns...so around 10 minutes...to purge a tank.

    So long story short - a combination between gradual purging and blowing down the tank a couple of times works wonders for us.

  10. #10
    Join Date
    Jul 2011
    Location
    Ft. Lauderdale, Florida
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    77

    Don't know...

    Like others posted in this thread (I think)...the brite tank is always CO2 pressure positive, even during cleaning. We only open her up once every month or so for a full caustic/acid/ster cleaning...otherwise, it's rinse/acid/PAA between fills...all under CO2 pressure. We just opened her up last week (120BBL brite) after a lapse of 2 months...besides some sludge pockets around the thermowell and carb stone...she was squeaky clean.

    For transfers, connect headspace, turn your pump on with a low VFD setting about 30 mins transfer for 120BBLs.

    As far as purging...we do this only when we open her up for the full cleaning...from the bottom-most port with the CIP arm vented...set your regulator to about 2psi and come back the next morning...she should be done by then. Close off the CIP arm, crank it up to 15psi and get ready to transfer.

    I always wonder, is there a better way to do this? I've heard some guys push beer from unitank to bbt while venting off CO2 from the bbt...i just thought maybe that was a waste of CO2 because then you have a dirty empty unitank full of co2 that you now have to clean...does that make sense? and you probably don't want to skip the caustic step on fermenters because of all of the krausen, yeast, and fermentation debris (hops, break, etc...). Does anybody out there not caustic cycle their fermenters after each use...please advise.
    Alex Postelnek, Lead Brewer
    Funky Buddha Brewery
    Ft. Lauderdale, FL 33334
    (561) 945 - 4584
    alex@funkybuddhabrewery.com

  11. #11
    Join Date
    Jul 2011
    Location
    Ft. Lauderdale, Florida
    Posts
    77

    Oh, nitrogen by the way

    oh...btw, i was wondering, does anybody use a blended gas (like 60-40) while packaging kegs off of their brite tank...i mean Co2 is expensive, N (using a blender) is free(ish). what happens in terms of product carbonation if you use a blended gas to keep head pressure on tank while packaging...also, what happens when you need to clean the tank for the next transfer? are there now going to be issues with 40% nitrogen in cleaning/packaging/getting accurate co2 readings? this would be helpful and save us a ton of CO2...
    Alex Postelnek, Lead Brewer
    Funky Buddha Brewery
    Ft. Lauderdale, FL 33334
    (561) 945 - 4584
    alex@funkybuddhabrewery.com

  12. #12
    Join Date
    May 2012
    Posts
    3

    Cool ditto

    Quote Originally Posted by jailhousebrewer View Post
    We've been in search of the best purge process for some time now. After discussing with other brewers how they are most successful, and after doing a good bit of testing ourselves, we've found that low pressure CO2 in the bottom of your tank and an open blow off arm works best. We have a DO meter we hook up to measure the oxygen levels. Once we hit our acceptable DO in gas we feel comfortable racking. Each tank seems to act differently but a good number to go by in our estimation is about 4psi CO2 feed for approximately 45 minutes to an hour. I'll be honest sometimes it takes longer and sometimes it goes faster than that. Without a meter it's just guessing. My opinion is if you use higher pressure and restrict outflow you cause more turbulence and mixing of O2 and CO2. Hope this helps.
    This is my method as well. 6 BBL brites.

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