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10 Questions & Answers About Draft Beer CO2

co2 101 north carolinaIn most draft beer dispensing systems, compressed carbon dioxide gas (CO2) is the primary gas used to get the beer from the keg to your glass (pressurized gas from the CO2 tank pushes the beer through the keg coupler via the beer line; from there, the beer travels up to the faucet tap and into your frosty glass).

But there’s more to CO2 than simply being a beer propellent. Here are some questions and answers about the gas that will help you get a better understanding of how to maintain a CO2-based dispensing system. If you need more information about CO2 refills or CO2 systems maintenance in North Carolina, contact the pros at James Oxygen – we’re CO2 experts!

CO2 Tank Q&A

1. Where can I fill a CO2 tank?

Aluminum gas tanks can typically be filled at your local welding supplier, such as James Oxygen.

2. What are the requirements for a CO2 tank?

The US Department of Transportation requires a CO2 tank be certified with their official markings, and re-certified every 5 years. Be sure to get a certified air tank and get them re-certified every five years at the same location you get it filled.

3. How many kegs can be dispensed from a CO2 tank?

A five-pound CO2 tank will last for between six and eight half barrels (full kegs) per fill; a ten-pound CO2 tank will dispense between 10 and 13 full kegs per fill. This number can rise or fall depending on how often you use your kegerator, the degree of carbonation required by your microbrew, and the condition of your system. At James Oxygen, we stock and fill 5-, 10-, and 15-pound CO2 tanks.

4. How do I check for CO2 leaks?

Some CO2 leaks produce and audible hiss; others are more difficult to detect. If your PSI level regularly drops overnight, you have a leak. Another way to check for leaks is using the “soapy water test”. Before you test for leaks, disconnect the beer keg and lower the PSI level to zero while keeping the CO2 tank engaged in the ON position. Spray soapy water on the connections in your system – if they start to bubble, there is a leak.

5. How do I fix CO2 leaks?

To fix CO2 leaks, first make sure that washers in the regulator and fittings are not damaged, worn or missing. Once you’ve checked and repaired/replaced them, reconnect your system and set the PSI level to 10. If there are still leaks, the CO2 tank level in the high-pressure gauge will go down within 10-15 minutes. If that’s the case, get a professional to look at your system.

6. What should my CO2 pressure be set at?

The ideal pressure for most beer is between 10-15 PSI, depending on what carbonation level the beer requires. Temperature can affect the required PSI as well: for most beers, the ideal pouring temperature is 38°F. If the temperature of your keg rises, you will need to raise the PSI level to compensate: raise PSI by one pound for every two degrees of temperature rise. Elevation also plays a factor, as it will lower the PSI value displayed on the low-pressure gauge. Raise the dispensing pressure by one PSI above standard for every 2,000 feet above sea level.

Your beer may be over-carbonated if it has an acidic taste and smell, very small bubbles and a rough texture. It may be under-carbonated if it’s still or tastes watery. 

7. How long should a typical pour take?

In a properly balanced system, it will take about eight seconds to fill a pint glass and one minute fill a one-gallon pitcher.

8. How do I read the CO2 pressure on my regulator?

A CO2 regulator typically includes two gauges: a high-pressure gauge, which typically reads between zero and 3,000 PSI (the pressure of air remaining in the tank), and a low-pressure gauge, which typically reads between zero and 60 PSI (the level your beer is poured at). Both gauges will give you clues to troubleshoot problems with your system.

9. How do you know when a CO2 tank is about to run out?

When the CO2 tank’s high-pressure gauge lowers from its initial reading, t’s time to refill. You can also often tell if you need a refill by weight: if the tank is easy to lift with one hand, it could be time for a refill.  Under-carbonation (a watery / flat texture in your beer) is also a sign your tank needs to be refilled.

10. Should a CO2 tank be inside or outside of the kegerator?

Ideally, both the beer keg and the CO2 tank should be stored inside your kegerator fridge: the lower the temperature of your compressed air tank, the more efficiently it will carbonate your beer. Other than exposing your tank to heat extremes, which can be extremely dangerous, the temperature of your tank will only make a slight difference in the performance of your beer dispensing system.