Most likely, the temp of the beer is higher than what you think. Air in the line means that co2 is escaping out of the beer. The higher the temp, the more pressure required to keep the co2 in the beer. At 38 and 12 PSI, you are fine. But if the beer is a higher temperature, you would need higher pressure (basic gas laws apply - PV=nRT). I would just make sure the beer is reading 38 degrees after you pour it.
|