A test for determining CO2 volumes in kegs

[kevink]

Let's say you have a keg perfectly carbonated to the ideal CO2 volumes at your serving temperature and pressure. For this example, let's assume that your CO2 volume is 2.3, your temp. is 42 degrees, and your pressure is 11 psi. What would the pressure gauge on your regulator read if you closed your CO2 tank, bled some pressure until the keg was at 5psi, and let it equilibrate? Will it eventually read your serving pressure of 11 psi?

Now let's say you carbed a keg to 1.5 times your normal CO2 volumes (overcarbed). For this example, we'll assume your CO2 volume is 3.44, your temp. is the same at 42 degrees, and the pressure is at 24 psi. If you now closed your CO2 tank, bled some pressure until the keg was at 5psi, and let it equilibrate, would it now go back up to 24 psi?

I'm trying to find a way to know how many volumes of CO2 are in a keg if you know the temp. and the pressure. Will this method work?

 

[thughes]

Why not just use the chart (if you know the temp and pressure)?

http://www.kegerators.com/carbonation-table.php

 

[kevink]

Yes, I know about the chart. I'm asking if there's a way to determine the CO2 volumes in a keg that you did not carbonate yourself or a keg that you carbonated haphazardly as in my example.

 

[RDWHAHB]

Not really sure what your after. But if you bleed off pressure from a keg that was in equilibrium and then seal it up then the new equilibrium pressure will be lower. How much lower will greatly depend on your beer to headspace ratio.

 

[JuanMoore]

Gas will come out of solution until it reaches equilibrium, which will be slightly less than the original pressure in your examples due to the gas being bled off, and the carb level will drop slighty as well. If the keg is fairly full and the headspace is minimized, the drop in pressure/carb level will be insignificant.

 

[JuanMoore]

Yes, I know about the chart. I'm asking if there's a way to determine the CO2 volumes in a keg that you did not carbonate yourself or a keg that you carbonated haphazardly as in my example.

Yes, if you can measure the temperature and equalized keg pressure, the chart will tell you what the carb level is.

 

[Bokonon]

You can buy or build something to hook a gauge to your disconnect. I'm pretty sure NB, midwest, and morebeer all sell something like this and I've seen quick guides around the net to do it.