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Old 02-23-2012, 08:13 PM   #11
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Gotcha...

Thanks, I'll call up the guy who did the prensation and tell him he's an idiot!

actually I won't... but that's helpful. Thanks.

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Old 02-23-2012, 10:00 PM   #12
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I think it is very dependent on yeast strain but I certainly don't have any recommendations as to how much for which yeast. I do lagers pretty exclusively and usually wind up running 15 - 20 ppm or a bit more. I get good results but won't say they might not be better at some other level.

The last time I brewed it was the club's 30th anniversary beer - a barley wine. The guy in charge of the yeast showed up with about a gallon and a half of slurry from a local brewpub. They said pitch it all so I pitched it all (50 gal batch). I ran the O2 at the usual 0.5 LPM as the fermentor filled but when I checked the DO is was only 4 mg/L, wait make that 3.5, no 3, no 2.5. There was so much yeast in there they were sucking up the O2 as we watched on the meter. That was quite a ferment!

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Old 02-23-2012, 11:02 PM   #13
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At work we're usually after 5-8ppm with a pitch rate of 5 million cells per ml (normally).

Today... the slurry I used must have been a bit thin as I only got 4.1 million cells/ml although I did manage 8.5 parts per million O2 by just using air through a sterile filter.

Using cal ale yeast we'll be at fg in under 4 days. This is 54hl in a conical (65 capacity?) with no top pressure btw

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Old 02-24-2012, 08:28 PM   #14
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People do it differently. I've had the best luck starting at around 5 psi from the beginning and then raising that to my desired carbonation level towards the very end. I'm not sure how this would help with layering, though, since fermentation (and thus CO2 production) should be all done by then.

I'm just looking for a simple way to leave my keg in the keezer for a couple months to lager without having a hose in a cup or airlock. I may give it a go and see if 1 or 2 psi will keep things neat and sanitary.
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Old 04-18-2012, 06:37 PM   #15
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I'm just looking for a simple way to leave my keg in the keezer for a couple months to lager without having a hose in a cup or airlock. I may give it a go and see if 1 or 2 psi will keep things neat and sanitary.
This is pretty much off the topic of the OP’s thread, but if you are trying to lager in a keg, just blast it with 20 psi or so and throw it in the fridge. The beer should be done fermenting before going into the ‘lagering’ state.
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Old 04-20-2012, 12:36 AM   #16
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Awesome thread! I love pressurizing with O2 in a sealed up fermentor.

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Old 04-20-2012, 10:26 AM   #17
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At room temperature 0.2 atm is going to give you about 8 mg/L. Thus pure oxygen at 1 atmosphere (open the bleed valve, put some O2 pressure on and let the O2 sweep out the air and then shut off the O2 and close the bleed valve) will result in about 40 mg/L. It might make more sense to pressurize to 2 atm (14.7 psig) with air as that gives a partial pressure of O2 of 0.4 atm and an equilibrium oxygen level of 16 mg/L.
But this isn't what they are asking. We want to know how much pressure O2 in a headspace is going to give us our total amount of O2 needed for the entire volume of beer. I think malfet is looking for an initial dose, that once shaken in (or left to absorb and diffuse), will result in the desired O2ppm... NOT the partial pressure of O2 that will give the desired ppm if the supply is unlimited, via a continuously connected tank/reg.

Yes, 8ppm at 0.2atm at equilibrium, but how much do we get from a given headspace to go into a given amount of wort at what pressure O2? Assume none goes into solution during the headspace charging....
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Old 04-20-2012, 06:08 PM   #18
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There are more difficult ways to get the same result if you want to be bothered by them by why make life hard?

In this case you know what your partial pressure of O2 will have to be 0.2 atm when the beer is at 8 mg/L. Multiplying the volume of the beer by 8 gives the total mg of O2 required and dividing by 32 gives the number of moles in the beer. Use P*V=n*R*T to get the number of moles in the heasdspace at 0.2 atm and add that to the moles in the beer to get the total moles. Instert into P = n*R*T/V where V is the headspace volume to get the partial pressure of O2 required initially in the headspace to reach the equilibrium values. Use air and compute 5*P as the desired pressure so the equilibrium total pressure will be 0 psig.

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