Originally Posted by musclebrew
I have 5ft lines with 3/16 tubing dispensing at 10psi@36 degrees am I over carbing the beer?
At sea level 36F @ 10PSI you would net 2.5v/v
A thing to keep in mind is that your regulator guage is going to show pressure over ambient. Therefore at sea level with an ambient pressure of 14.6PSI and a regulator PSIG (guage pressure) of 10PSI your "absolute pressure" in your keg is 24.6PSI (absolute pressure is the pressure over total vacumn. PSIG is guage pressure over ambient)
At higher elevations the ambient pressure is lower so a correction is required on your PSIG to achieve the required absolute pressure for your target carbonation level.
If we apply the previous example of 36F and 10PSI in Denver then you would have a lower absolute pressure since ambient would be lower and consequently your carbonation would only be about 2.2v/v
BTW. this is also very temperature related. at 0' elevation, @ 10PSIG, and going from 36F to 38F your carbonation drops from 2.5v/v to 2.4v/v. Or put another way... if you carbonate at 10PSIG at 36F but try and serve at 38F with 10PSIG you will theoretically get foam due to 'breakout' as that difference of 0.1v/v tries to escape from your beer (this is a very minor difference, so it would probably be manageable). This is why warm beer foams.
A higher pressure would be required at the warmer temperature to keep the dissolved gas in the beer, and consequently a longer piece of restriction/choke line would be required to balance the pressure and control the rate of your pour.