Mixing CO2 and N2?

Is it possible for a homebrewer to mix their own beer gas without spending more than $200 on a mixing valve thingamajigger?


The reason I ask is I have a nitrogen tank and regulator for filling the shocks on my off road car and I would like to know if it would be cheaper to get a mixer than it would be to buy a seperate bottle and regulator for beer gas. Somehow I doubt it, but I guess its worth asking.

You would need to mix it to the 80/20 split for beer gas (nitrogen/CO2) which could get rather tricky...

Why not naturally carbonate the brew, or carbonate it with CO2, then push it with nitrogen? You don't need to use beer gas to push it, you could just use nitrogen.

Personally, when I get into kegging, and put in a stout tap, I'll have a dedicated nitrogen/beer gas cylinder for that tap.

So beer gas is just the lazy man's way of carbing and serving using only one tank?

If forced carbed on CO2, then pushed with nitrogen, do you still get the cascade if you use a stout faucet?

Pretty sure there's not enough CO2 in beer gas to carbonate... At least not at the pressures you'll be using, and without letting it sit for a long, long time. To get the CO2 part up to what you'll need for carbonation, the pressure would probably be insane.

Someone that's used the pure nitrogen with the stout tap will be able to say for certain, but I'm pretty sure that you'll get the cascade and Guinness style head with Nitrogen and the stout tap. Without the stout tap you won't get the same effect with nitrogen.

You might be able to get something close with a creamer faucet, if you don't want to setup the stout tap/faucet. If you already have the faucet, then I would just get the tank and regulator to feed it properly. Try one fill with beer gas and another with straight nitrogen. Compare results and see which you like better.

WTF_Brewing said:

Is it possible for a homebrewer to mix their own beer gas without spending more than $200 on a mixing valve thingamajigger?


The reason I ask is I have a nitrogen tank and regulator for filling the shocks on my off road car and I would like to know if it would be cheaper to get a mixer than it would be to buy a seperate bottle and regulator for beer gas. Somehow I doubt it, but I guess its worth asking.

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Yes, you can get by without the mixing valve. Instead, you can use a technique common amongst technical scuba divers (and perhaps others) called partial-pressure blending. In other words, you could begin by carbonating your beer to the appropriate level with pure CO2 from the CO2 tank you already have. Then, once the beer has the appropriate level of CO2 you switch over to a tank of pure nitrogen.

As an example, if you determine that you want your stout to have 1.5 volumes of CO2. So you figure out what the appropriate CO2 pressure is to achieve that carbonation level, given the parameters of your system. Let's just say that's 10psi. So you set the CO2 regulator to 10psi and allow sufficient time for the beer to carb. Once that's done, take the CO2 gas line off the keg and switch over to the nitrogen line. Now your stout faucet produces additional back pressure in the line from it's restrictor plate, so the pressure that you'll have to set the nitrogen regulator at will be significantly higher. I'd start out around 25 or 30 psi and see how it goes from there. You can adjust up or down as necessary. The pressure of the nitrogen in the headspace of the keg will keep the CO2 in solution, and the beer will actually take up some of the nitrogen too. Beer doesn't absorb *nearly* as much nitrogen as it does CO2, but it will take up some. So now you've got CO2 in the beer as well as nitrogen, and you're pushing the beer with higher pressure nitrogen which will overcome the inherent back pressure from your system as well as the extra back pressure from your stout faucet's restrictor plate and give you the nice creamy head you desire. If you're particular about hitting an 80/20 split for the gas in your beer then you would set your nitrogen regulator at 40 psi (since you set the CO2 at 10 psi). But I typically use a bit more of a guess work approach and get the pour the way I like it, rather than obsessing over getting an exact split of gas.

Sorry for the lengthy, geeky post. But this is one area where my love of beer brewing and my love of scuba diving run together.

Brian

Golddiggie said:

Pretty sure there's not enough CO2 in beer gas to carbonate... At least not at the pressures you'll be using, and without letting it sit for a long, long time. To get the CO2 part up to what you'll need for carbonation, the pressure would probably be insane.

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When you use 75%:25% beer gas, your beer carbonates at 25% of the pressure you set the beer gas to. So if you set it to 30 psi, you get the equivalent of 25% of 30 psi (or 7.5 psi) carbonation per any of the carbonation tables. A lot of that carbonation will come out of solution when it goes through the restrictor disk in the stout tap (by design).

Here's the first paragraph from the wiki Partial Pressure page:

In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture.

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Just a thought WTF, could you fill your shocks with beer gas? That seems like it would be the easiest solution if possible.

Thanks guys! That helps a lot. I don't have any experiance with mixing gasses.

Nitrogen is used in offroad racing because it doesn't expand or contract when the temps change (as the shock heats up) like regular air or CO2. I think the easiest way to see that in action is when you put the CO2 tank in the fridge and the pressure guage reads lower.

I also use nitrogen in the tires on my wifes car cause it has the tire pressure monitors. Those damn things are so sensitive that a couple lbs low is enough to make the idiot light come on. Before I used N2, in the winter, when temps dropped to single digits, the pressure in the tires would drop enough the light would come on. That is part of the reason its also used in aircraft tires.