To Bleed or Not to Bleed

dan_s · October 2, 2014, 12:05am

Hello Everyone,

A question:

I have an Oatmeal Stout that I have carbed at basement temperature. My basement is currently sitting at 68* and so I set the pressure to 20 PSI to achieve a carbonation level of 2 volumes of CO2, per the calculator I used.

Space has opened up in my keezer to place the keg inside to cool off, but I do not yet have a gas line available. My keezer is set at 45*, which would require a dispensing level of 9 PSI to maintain my 2 volumes of CO2. My question is: will leaving the keg in the keezer at 20 PSI, but not hooked up to gas, over-cabronate the beer? I’m wondering if I should bleed the keg now and then top it back up at 9 PSI until I’m ready to leave the gas hooked up for dispensing.

Am I over-thinking this?

old_dawg · October 2, 2014, 6:06pm

Two volumes of CO2 at 68F, when cooled to 45F will still be two volumes of CO2. The pressure should drop from 20 psi to 9 psi, but the volume of dissolved CO2 will be unchanged.

You can confirm my theory by closing the CO2 tank valve and hooking the gas line to your keg. If I’m understanding the physics correctly your gauge will read 9 psi. If it doesn’t, please post your results here so I can re-think what’s going on.

65ss427 · October 3, 2014, 1:06am

[quote=“Old_Dawg”]Two volumes of CO2 at 68F, when cooled to 45F will still be two volumes of CO2. The pressure should drop from 20 psi to 9 psi, but the volume of dissolved CO2 will be unchanged.

You can confirm my theory by closing the CO2 tank valve and hooking the gas line to your keg. If I’m understanding the physics correctly your gauge will read 9 psi. If it doesn’t, please post your results here so I can re-think what’s going on.[/quote]

^^^^^^Correct. :cheers:

dan_s · October 3, 2014, 3:51pm

Thanks guys - I actually got antsy and wound up bleeding the keg and topping it up to 9 PSI, just to be safe, but I can certainly follow your logic, Dawg. My current kegging system will include carbing at room temperature from this point forward, so next time around I will follow your advice and confirm the drop in pressure that you mentioned.

Thanks again!