Do CO2 regulators show incorrect PSI in cold temps?

nibiyabi · Mar 1, 2009

I have had to turn my CO2 up to ~15-20 PSI (according to the regulator) just to get a decent head on my tapped beer. I sprinkled soapy water all along the connections to check for leaks but had no bubbling. I don't hear any hissing from the CO2 tank. The level of CO2 remaining appears to be constant over periods of time when I don't pull any beer. Could it simply be that the PSI meter is inaccurate in <40ºF temperatures?

P.S. I have it at 38ºF because that's the recommended serving temp for the beer I have in there. Maybe that could be it, because I know warmer temps make more foam. . . .

Coy-Boy · Mar 1, 2009

I have my tank in the fridge with no problem. I serve aroung 39 at 12 psi and it is perfect. I have aroung 6 foot of 3/16 beverage line and it is a great pour.

nibiyabi · Mar 1, 2009

That's the other thing I forgot to mention -- my beverage line is no more than 3-4 feet long.

boogyman · Mar 2, 2009

I'm reasonably sure temperature does not affect the reading of the psi for your output lines since the co2 is already in gas form. However, the reading for the tank pressure might be lower since that co2 is still in liquid form.

Quan · Apr 6, 2010

Pressure is pressure. If your regulator is functioning properly, the pressure reading on your regulator is the pressure exerted.

As far as your tank pressure gauge (the one that goes from 0-2000)... that one will drop as temperature goes down. The reason for this is that as temperatures get colder, the density of the gaseous CO2 in the tank lowers, thus lowering pressure. At room temperature, the tank pressure should read about 800-900 psi. In the 30s, it should read somewhere in the 500-600 psi range. There are formulas to calculate these values exactly (I believe it is the ideal gas law "PV=nRT")... but these are general numbers

As far as your regulator gauges, temperature will change the gas density, thus, at colder temperatures, you will have higher concentrations of CO2 given the same pressure. Ultimately, this will change your volumes of CO2 but your pressure should stay at whatever you set it at.

To answer your question, no, temperature should not effect the accuracy of your pressure reading. As for why you have flat beer... (I assume this is what you mean by getting no head) that is a 'whole nother story. It could be from a CO2 leak... the whole soapy water thing doesn't really work with CO2 leaks since that CO2 is coming out at about 500-800 psi... it ain't gonna make no bubbles =P. The best way to test your CO2 system is to pressurize the whole system... say to 30psi, and then shut off the knob on your CO2 tank... if that pressure drops below 30psi within a 10 minutes or so, then you have a significant leak.

If by "no head" you mean "no head but it's still carbonated"... then I'd be lookin' at your recipes or check to make sure you don't have grease all over your glass or something. =P

Clear as mud?