beer gas or straight nitro

Is beer gas (75% nitro, 25% CO2) necessary if I force-carb ahead of time with 100% CO2? The reason I ask is:

1. I can get refills with 100% nitro much cheaper than a beer-gas mix
2. I am wondering if I keep the pressure at 30PSI (a typical level for pouring with nitro through stout faucets) if over time, the 25% CO2 in the beer-gas mixture will start to carbonate my beer beyond my original desired level.

herman2011 said:

Is beer gas (75% nitro, 25% CO2) necessary if I force-carb ahead of time with 100% CO2? The reason I ask is:

[*]I can get refills with 100% nitro much cheaper than a beer-gas mix
[*]I am wondering if I keep the pressure at 30PSI (a typical level for pouring with nitro through stout faucets) if over time, the 25% CO2 in the beer-gas mixture will start to carbonate my beer beyond my original desired level.

Click to expand...

Boy did you ask a mouthful. The overcarb question is easy. N2 does not dissolve well into liquid beer. You can crank up the pressure quite high and not risk over carbonation, the beer will just come out of the tap faster or be able to be sent over long runs of beer line. That's why bars use beer gas which is part N2, so they can use 30psi to drive beer from the keg room 100 feet away.

The other part is more complex. This is a partial pressure of gasses problem. The quick and dirty answer is you can use 100% N2 if you will finish your beer in a day or two. Otherwise, you won't like the result. When you start a new keg that you first carbonated and is under pure co2 you have a few things. You have some volume of liquid, into which is dissolved some volume of co2. You also have a small amount of headspace at the top of pure co2 at your initial pressure, maybe 10 psi? Constantly, some amount of co2 is coming out of solution but an equal volume going back in. When you connect the keg to a 10 psi n2 tank, nothing happens (no mixing gas because of the regulator), but as you serve beer, n2 gas at 10 psi, replaces liquid volume. CO2 will come out of solution in proportion to the moles (absolute unit of measure for number of molecules of a chemical) of CO2 vs moles N2 in the keg, both in solution and in the head space. As the headspace grows from serving beer, co2 will come out of solution, with no new co2 added. Your beer will go flat while being served at 10 psi. It will go flat faster at 30 psi, because the process starts as soon as you connect the keg and their are more total liters of gas.

can you put it in simpler terms? i was thinking about getting a beer gas setup for my keezer i'm building.. what is the recommended way of serving/storing something with that.. force carb with co2, then once carbed replace the headspace with 30psi beer gas and keep it that way? how long would that keep good w/o losing carbonation?

herman2011 said:

Is beer gas (75% nitro, 25% CO2) necessary if I force-carb ahead of time with 100% CO2? The reason I ask is:

[*]I can get refills with 100% nitro much cheaper than a beer-gas mix
[*]I am wondering if I keep the pressure at 30PSI (a typical level for pouring with nitro through stout faucets) if over time, the 25% CO2 in the beer-gas mixture will start to carbonate my beer beyond my original desired level.

Click to expand...

You can use 100% nitro (or argon) as others here have done, but you'll slowly lose carbonation as the keg empties. The question is whether or not the savings are worth the slight decline in carbonation. Some claim that the decline in carbonation is pretty small, but I have no firsthand experience myself.

If using beergas, you'll want to set the pressure so that it maintains your desired carb level (just like you do with 100% CO2). This is usually between 30 and 40 psi for most people, but it may need to be higher or lower depending on your serving temp, desired carb level, and which beer gas blend you're using (70/30 and 60/40 are other common ones). Using the 75/25 blend and 30 psi you mentioned would typically be for beers in the 1.2-1.3 vol range.

Here's a calculator that you can use to determine the proper pressure using a given gas blend-http://mcdantim.mobi/easypsig

krenshaw said:

can you put it in simpler terms? i was thinking about getting a beer gas setup for my keezer i'm building.. what is the recommended way of serving/storing something with that.. force carb with co2, then once carbed replace the headspace with 30psi beer gas and keep it that way? how long would that keep good w/o losing carbonation?

Click to expand...

You can prime to carb naturally, force carb with 100% CO2, or force carb with beer gas, but using beer gas takes longer and is more expensive, so it's not usually recommended. The beer gas is designed to maintain a low carbonation level while using the much higher pressure needed to make use of the restrictor plate in a stout/nitro faucet. If properly balanced, it won't change the carbonation level at all.

How is CO2 blended to Nitrogen over 600psi pressure in vessel, because the CO2 will be in liquid state, and the Nitrogen in gaseous? Is the Nitrogen first burst out from the vessel (until the pressure drop under 600psi) and then the CO2 start to vaporize (mixing gaseous together with nitrogen gaseous)??