Searching, but unable to find the answer to this. Are there any problems that I can expect if I fill my 5 gallon kegs with, say, 2.5 or 3 gallons of beer? Are the processes for carbonating the same as if I used 5 gallons of beer?
Kegging less than 5 gallons in a 5 gallon corny
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Suthrncomfrt1884
Well-Known Member
Same process, no problem.
+1 no problem. Have done this many times.
chuggs
Well-Known Member
A wee bit more oxidation potential...otherwise, not a problem...
Couldn't you just purge the space with CO2 to fix that?
springer
Well-Known Member
not really .. Well maybe at first but once a full 5 gallon corny gets down to 3 then it will have the same amount of CO2 in it as one that starts with 3. The way I see it will even out at the end since you are always topping the CO2 off.
The key is, "maybe at first". That first bit will never be made up. Once the 5 gallon keg gets down to 3 gallon they should take about the same CO2. But, you served 2 gallons of delicious beverage. On the 3 gallon all you've done is fill up the headspace.
It will take more CO2 (per gallon) than the 5 gallon. Not that much though.
It will take more CO2 (per gallon) than the 5 gallon. Not that much though.
chuggs
Well-Known Member
Yes...I don't know that it would actually wind up being a problem. It's just easier to get a good purge from a small headspace vs a large headspace.
If purging were perfect...refrigeration people could just purge the air out of the line with refrigerant. Unfortunately, it's not effective enough...so they wind up putting a vaccum on the system to get all the air out before they fill it with refrigerant.
I think the potential for oxidation is going to be just a wee bit higher --- than if you filled the keg w/ 5 gals of liquid.
JKoravos
Well-Known Member
More per gallon, less overall.
Presuming the keg is exactly 5 gallons, 5 gallons of beer will hold, let's say, 2.5 volumes of CO2. IOW, 12.5 gallons of CO2 at atmospheric pressure and 32F (the reference state for volumes). If the keg has 3 gallons of beer, the beer will contain 7.5 gallons of CO2. The remaining two gallons of headspace will contain pressurized CO2 at equilibrium. If the keg is being carbed at 40F, the pressure is 1.85 atm. This will account for (1.85v x 2gal=) 3.7 gallons of CO2 at 1atm and 40F, or 3.64 gallons at 1 atm and 32F. Giving you a total of 11.14 gallons total to carbonate 3 gallons to 2.5 vol in a 5 gallon at 40F.
Arkador
Well-Known Member
CO2 is heavier than air, so even if the head space it only half full of CO2, it is going to form a cushion over the beer, keeping the oxygen away from the beer.
Clayton
Well-Known Member
you arnt taking in to acount the 2 volumes of gas to carb, a full keg will need more gas because you are carbing more water and still purging all the beer out of the same 5 gal volume so the dispence gas will be the same.
JKoravos
Well-Known Member
That's a common misconception and is absolutely not the case. If there is any oxygen in the keg, it will come in contact with the beer.
farmbrewernw
Well-Known Member
Not true, actually CO2 is heavier than air, there is a village in Africa that lives at the base of a volcano that has a lake on the top of it. This particular volcano degases CO2 which collects at the bottom of the lake, when the pressure of CO2 gets high enough or if something disturbs the lake the lake overturns and releases the CO2. The CO2 being heavier than air runs down the mountain and collects in the lowest places. The whole village died because of this.
Anyway CO2 is heavier than air, I work at a brewery and when we clean our tanks I can see the CO2 running out the bottom or our fermenters. We still use dairy tanks for some of our primary fermentation and as long as we purge partially the tanks before we transfer we have that blanket of CO2 to keep the O2 from touching. If you where to shake that fermenter sure the O2 would get to the beer but if left untouched that CO2 will keep O2 from contact.
Anyway CO2 is heavier than air, I work at a brewery and when we clean our tanks I can see the CO2 running out the bottom or our fermenters. We still use dairy tanks for some of our primary fermentation and as long as we purge partially the tanks before we transfer we have that blanket of CO2 to keep the O2 from touching. If you where to shake that fermenter sure the O2 would get to the beer but if left untouched that CO2 will keep O2 from contact.
Kauai_Kahuna
Well-Known Member
Man I feel like I'm having lunch with a bunch of engineers. Actually most of you probably are.
Just purge the air out, charge it with Co2, let it sit a few minutes, let out the air on top. Repeat until you think you got it all.
Just purge the air out, charge it with Co2, let it sit a few minutes, let out the air on top. Repeat until you think you got it all.
JKoravos
Well-Known Member
CO2 is heavier than air, but it does not provide any type of meaningful blanket effect preventing oxygen from contacting beer. The oxygen will easily diffuse through the CO2 and absorb into the beer.
Ask yourself this...Nitrogen is 15% lighter than oxygen, so why doesn't the nitrogen and oxygen in air separate and leave us with a layer of 100% oxygen closest to the earth's surface?
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