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 Home Brew Forums > Calculating CO2 Volumes in a keg
05-05-2011, 10:48 PM   #1
Brew-medic
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 Calculating CO2 Volumes in a keg

Anyone attempt to calculate this, as I am stumped on how to do this. I have a rig that calculates it after bottling. I want to ensure that I am bottling at the correct carbination.

I think this would work, tell me if I am on the right track.

Bleed the pressure in the tank, then leave at 2˚C for 24 hours, take a reading, and calculate that into the volumes of CO2

Or does someone else have a better idea?

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05-05-2011, 10:53 PM   #2
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Well, if the carbonation/temperature charts are accurate, that would be the easiest way to me.

For example, in this chart:

if your beer/keg is at 37 degrees, and the psi has been at 15 psi for long enough to be equalized/fully carbed, the volume of co2 has to be 2.90.

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05-06-2011, 03:30 AM   #3
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But do you think that bleeding off the excess co2 then leaving it for 24 hours and then measuring the best?

I have a contraption that measures Volumes that we use after bottling, 1 day, 2 day, 7 day, 14 days after bottling to see what is lost via caps

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05-06-2011, 03:38 AM   #4
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Quote:
 Originally Posted by Brew-medic But do you think that bleeding off the excess co2 then leaving it for 24 hours and then measuring the best? I have a contraption that measures Volumes that we use after bottling, 1 day, 2 day, 7 day, 14 days after bottling to see what is lost via caps
I would say Yooper is correct, if the beer has stayed at a certain temperature and pressure for a decent amount of time it will have equalised so that you can read the CO2 volumes off a chart (assuming that chart is correct )
I'm guesing you device to check carb in the bottles is one of the piercing things? don't know how to use them but I'm sure it is basically the same method, wait for the beer to equalise/pierce the cap or can/read the pressure/check pressure against temperature on the chart and you got your CO2 volumes.
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05-06-2011, 05:10 AM   #5
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Quote:
 Originally Posted by Brew-medic But do you think that bleeding off the excess co2 then leaving it for 24 hours and then measuring the best? I have a contraption that measures Volumes that we use after bottling, 1 day, 2 day, 7 day, 14 days after bottling to see what is lost via caps
I'm confused as to what exactly you're trying to do. If all you want to know is the carbonation level in the keg, just use the chart above or any one of the similar charts online. What excess pressure are you talking about bleeding off? Are you priming and naturally carbing in the kegs or something?
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05-06-2011, 12:15 PM   #6
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Well lets say you have your keg at 40 psi to get ready to bottle, the disolved co2 is not going to be what equals in the chart because, not 100% of the co2 will get disolved. For example, if you were to pressure up a keg to 40 PSI, notwithstanding any leaks, disconnect the co2, and leave it over night your pressure drops. Because we bottle, we only bottle at about 2 psi from keg to bottle to avoid disturbing the liquid and bringing out the co2. So what I am figuring out is how much co2 is disolved and converting it to volumes. This way I have a consistent bottling practice.

I talked to one of the Big 2 bottling manufacturers and they said they have a huge problem after bottling, PET caps are horrible for leakage and from day 1 to day 7 it is not abnormal for a bottle to drop 1 or 2 volumes, and a brewer here says the same thing about crowned glass bottles.

Quote:
 Originally Posted by JuanMoore I'm confused as to what exactly you're trying to do. If all you want to know is the carbonation level in the keg, just use the chart above or any one of the similar charts online. What excess pressure are you talking about bleeding off? Are you priming and naturally carbing in the kegs or something?
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05-06-2011, 01:17 PM   #7
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How about pressurizing and letting it aborb the co2 where it will equalize out (which is why there's the pressure drop if you first set it to 40psi, then disconnect), then after a few days once it's stabilized, take a psi reading using a spunding valve or other psi measurement device that you just push onto the air side of the keg, then using the chart to calculate the volume of co2?

More than likely, what you're asking is how to calculate volumes of co2 during a quick carbing. Where you start off with fresh beer, carb & shake, and then try to figure out whath the volume of co2 currently is based on the psi you were using.

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05-06-2011, 10:16 PM   #8
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The pro's test their cans, bottles, kegs and bright tank's to make sure they have consistent and accurate C02 vol. in all their product's. This is done with precise testing equip.http://www.zahmnagel.com/Products/tabid/57/Default.aspx that's quite expensive, and just to costly for a homebrewer or even at my
small brewpub level. I think the chart method is pretty accurate, given the beer has been held at same pressue & temp for a reasonable amount of time.
Cheers!!

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05-07-2011, 12:52 AM   #9
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Quote:
 Originally Posted by Brewerforlife The pro's test their cans, bottles, kegs and bright tank's to make sure they have consistent and accurate C02 vol. in all their product's. This is done with precise testing equip.http://www.zahmnagel.com/Products/tabid/57/Default.aspx that's quite expensive, and just to costly for a homebrewer or even at my small brewpub level. I think the chart method is pretty accurate, given the beer has been held at same pressue & temp for a reasonable amount of time. Cheers!!
Off-topic, but I love the picture in your avatar! That's awesome. I keep saying I'm going to take a day and come visit the brewery- and I will! Life has been very busy for me right now, but I'm dying to come for a visit!

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05-07-2011, 12:40 PM   #10
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I aquired one from a business that went out of business, and the bank didnt know what the heck it was at the auction, snapped one up for like \$50.00, I do some testing for a few local brewers

Quote:
 Originally Posted by Brewerforlife The pro's test their cans, bottles, kegs and bright tank's to make sure they have consistent and accurate C02 vol. in all their product's. This is done with precise testing equip.http://www.zahmnagel.com/Products/tabid/57/Default.aspx that's quite expensive, and just to costly for a homebrewer or even at my small brewpub level. I think the chart method is pretty accurate, given the beer has been held at same pressue & temp for a reasonable amount of time. Cheers!!
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