CO2 Pressure Gauges at Kegerator Temps

Do CO2 regulator pressure gauges read correctly at kegerator temps (37-38 °F)?

The reason I ask is that I have been carbing my kegged beers by setting the regulator at 13psi and letting it sit for a week or two. 13psi is higher than what i see most people using, however, the carbonation is still not all that strong in my beers. According to carb charts at 37 degrees and 13 psi, I should be at around 2.7 volumes of CO2 which is very amble carbonation, however the beers i pour are surely nowhere near 2.7 volumes.

So, I am suspecting that my regulator is not registering the correct pressure at these cold temps. Could this be right? 13 psi should be 13psi right?

pressure is pressure. You do not have to compensate pressure reading for temp like you would a hydrometer - for example. Your gauge could certainly be out of calibration, but it's not because of the temperature

how would i go about calibrating the gauges?

not sure to be honest. If you have a friend you can temporarily swap gauges with. it might tell you if it is really off or not.

The easiest way would be to hook up a secondary regulator, turn it all the way up, and see what it reads.

I was getting odd reading when I had mine in the kegger too. I drilled a hole in the bottom back left area of the fridge and ran a 3/4 inch sleeve through it to fill the hole then ran my line through that taking up the rest of the space. I moved the fridge a few inches to the left and put the bottle outside and all has been well since.

Special Hops said:

pressure is pressure. You do not have to compensate pressure reading for temp like you would a hydrometer - for example. Your gauge could certainly be out of calibration, but it's not because of the temperature

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I am pretty sure pressure changes with temperature. hence PV=nRT
Right now my CO2 tank is in the fridge and it says its filled to 500 PSI if I take it out of the fridge that reading will change to around 800 PSI.
Not sure if you need to compensate for temperature or not. Maybe try taking your CO2 tank out of the fridge for a bit then hook it back up to the tank at 12PSI and listen to see how much gas is exchanged.

Bheher said:

I am pretty sure pressure changes with temperature. hence PV=nRT
Right now my CO2 tank is in the fridge and it says its filled to 500 PSI if I take it out of the fridge that reading will change to around 800 PSI.
Not sure if you need to compensate for temperature or not. Maybe try taking your CO2 tank out of the fridge for a bit then hook it back up to the tank at 12PSI and listen to see how much gas is exchanged.

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The low pressure side of the regulator is not subject to the same pressure changes because the keg temperature is all that matters. 13psi is already adjusted to keg temperatures, otherwise it would be like 27psi.

As for why your beer is not carbonating, I had a weird phenomenon in mine that eventually I attributed to elevation. You should up your psi reading by 1 for every 2000ft you are above sea level. I think I have a link in my sig too...

If that isn't it, can you give us some more details? Like, the beer is carbed but no head? The beer tastes flat? The beer seems well carbed, but just not to 2.7? Any details could help.

Bheher said:

I am pretty sure pressure changes with temperature. hence PV=nRT
Right now my CO2 tank is in the fridge and it says its filled to 500 PSI if I take it out of the fridge that reading will change to around 800 PSI.
Not sure if you need to compensate for temperature or not. Maybe try taking your CO2 tank out of the fridge for a bit then hook it back up to the tank at 12PSI and listen to see how much gas is exchanged.

Click to expand...

That is the high pressure side. He is talking about the low pressure side. While pressure does change with temp. Anyone's 13psi keg pressure at 40 deg temp should yield identical carbonation.

thanks for all of the thoughtful responses.

dkershner - i'm at less than 500 ft above sea level, so while thats a good point, i don't think thats the problem. My beers have carbonation, its just not what i would expect from 2.7 vols (13 psi at 37 degrees for 2 weeks). My beer is not as carbed as commercial craft beers are from the bottle and at 2.7 vols I would expect it to be. Are my expectations wrong?

last night i hooked up a tire pressure gauge to the gas-out of the CO2 regulator set at 15 psi. The tire pressure gauge read 18psi !? I don't know what thats all about, but i'm assuming the tire pressure gauge was wrong since otherwise my beer should be way overcarbed which its not. All very confusing.

Anyway, thanks again for the responses. I have decided to just adjust the regulator based on how I like the beer. If the regulator says 15psi, but the beer tastes right to me, thats where i'll leave it.


One more question. Once the beer is properly carbed to your liking, do you guys then drop the pressure to a lower 'serving pressure' for the remainder of the beer's life? Or do you hold the beer at the pressure that was used to carb the beer during serving as well?