As an expert sommelier and brewer, I can confidently say that estimating the number of kegs a 20lb CO2 tank will last can be a bit tricky. However, I can provide you with some general guidelines based on my personal experiences and industry knowledge.
Firstly, it's important to note that the number of kegs a CO2 tank can dispense will vary depending on several factors, including the size of the kegs, the desired carbonation level, and the dispensing pressure. It's also worth mentioning that carbonating a keg requires more CO2 compared to simply dispensing beer.
According to Micromatic, a reputable manufacturer of draft beer equipment, a 20lb CO2 tank can dispense approximately 62 to 87 5-gallon kegs. However, this estimate is specifically for dispensing beer and does not account for carbonation. Carbonating a keg typically requires higher amounts of CO2, as the gas is absorbed by the liquid to create the desired level of carbonation.
In my brewing experience, carbonating a keg generally uses more CO2 compared to dispensing alone. The exact amount of CO2 needed for carbonation depends on various factors such as the desired carbonation level, temperature, and the type of beer being carbonated. For example, lagers may require higher levels of carbonation compared to ales.
To give you a rough idea, a typical carbonation process for a 5-gallon keg might involve setting the regulator to around 12-15 psi (pounds per square inch) and leaving it at that pressure for a few days. Once the desired carbonation is achieved, the pressure can be reduced to the dispensing pressure, which is usually around 8-12 psi.
Based on my own experience, I estimate that carbonating a 5-gallon keg may require approximately 1-2 pounds of CO2, depending on the factors mentioned earlier. Keep in mind that this is just an estimate, and the actual amount of CO2 needed may vary.
To summarize, while Micromatic suggests that a 20lb CO2 tank can dispense around 62 to 87 5-gallon kegs, this estimate does not account for carbonation. Carbonating a keg typically requires more CO2 compared to dispensing alone, and the exact amount needed can vary depending on various factors. It's always a good idea to monitor your CO2 usage and have a spare tank on hand to avoid running out during crucial brewing or dispensing moments.