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> Beer Gas, contributed by pods8
cj in j
post Dec 20 2005, 07:14 AM
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Beer Gas FAQ
AKA: Guinness/Nitrogen/Stout Pour
Contributed by pods8

This FAQ is a compellation of basic beer gas knowledge I've acquired during my pursuit to install a "stout" faucet on my kegorator. Thanks to all who helped provide various knowledge tidbits. If you see errors or have futher questions PM me and I'll see what I can do. (IMG:style_emoticons/brewboard/smile.gif)

Q: How do I get that creamy head/ mouth feel of Guinness?
A: There a few methods that I am aware of. The first two are cheap MacGyver methods that I have not personally tried but here they are none the less. When pouring a stout through a regular faucet, close the valve part way once the beer is almost full, which should create a larger head to form. Or use a syringe to suck some beer up from your glass of beer and squirt it back into the beer with the tip submerged in the glass (this would be useful for bottled beers) -- theoretically it causes more CO2 to come out of solution and create a large head. Be careful not to squirt too much or you may have a foam-over mess.

The other option, and the point of this write up, is to use beer gas, the perfect kegorator addition for someone with extra cash burning in their pocket. (IMG:style_emoticons/brewboard/wink.gif)

Q: What is beer gas?
A: Beer gas is a nitrogen and CO2 mixture. Common ratios are 70/30 or 75/25. Nitrogen is an inert gas that doesn't dissolve well into beer, which gives beer gas two main uses. First off it can be used to push a beer through a "stout faucet" that has a restrictor plate (basically a plate that has some small holes in it), which strips some of the dissolved CO2 out of the beer to form the classic Guinness head and silky mouth feel. To get beer to properly pour through a stout faucet, a lower volume of dissolved CO2 is required in the beer as well as a higher serving pressure, which is why regular CO2 on its own doesn't work very well.

The second use for beer gas is in situations when a large amount of restriction needs to be overcome to serve a beer, i.e. a bar that has its kegs in a back room, 100' of beer line away from the taps. A greater pressure is needed to transport the beer to the taps. However if using regular CO2, the beer would become greatly overcarbonated. By using a proper ratio of nitrogen/CO2, a bar is able to provide the proper pressure and volumes of dissolved CO2 because the nitrogen fraction only provides pressure on the beer and does not dissolve into the beer readily. This use has its own complexities, which will not be further explored in this FAQ.

Q: Where do I get beer gas and what type of tank/regulator do I need?
Anywhere that provides an assortment of compressed gasses likely carries beer gas or can obtain it if requested. You may either be able to get your tank filled on the spot, exchange your empty tank for a full one, or drop your tank off and wait while they send it in somewhere to be filled. I get my beer gas from a welding supply shop doing a tank exchange. The cost is around 1.5x that of a CO2 fill for the same size tank, last time I had mine filled. If you are having difficulty locating a supplier, find a bar that serves Guinness and ask who supplies them. Keep in mind different people may call the gas different names -- try beer gas, Guinness gas, nitrogen-beer mix, etc.

As for a tank, you can either use a standard CO2 tank or a nitrogen tank and corresponding regulators -- note there are differences in the fittings on the regulators so they are not interchangeable. You could change out the stem and nut on the regulator to adapt it to the opposite tank. However, I do not advise doing because nitrogen regulators are designed for much greater pressure than CO2 regulators and adapting a CO2 regulator for use on a nitrogen tank could result in serious harm. Adapting a nitrogen regulator to a CO2 tank could likely be done reasonably. However I still say use the proper regulator with the tank its designed for. (I assume no responsibility for your choice to experiment with regulators and tanks containing high pressure gas!)

With that said, a CO2 tank/regulator combo is rated for 1800 psi where as a nitrogen tank/regulator is rated for 3000 psi. Thus a nitrogen tank will hold more gas for the same size tank. However a CO2 tank and regulator are likely more prevalent at a better cost for most homebrewers and also provide the option to still be used for CO2 usage in the future. If you decide to go the CO2 tank route, a 20 lb tank is recommended (and often the only size offered by suppliers) because beer gas is in a gas state while in the tank whereas CO2 is liquid in the tank with a gas layer on top. Thus for the same size tank, CO2 will last much longer than beer gas so one may as well use the largest practical standard CO2 tank.

I personally use a 20 lb CO2 tank because I had an extra CO2 regulator handy when I decided to add a beer gas system, and I was able to get another CO2 tank cheaper than what a nitrogen tank would have cost me. I also liked the option of being able to use the tank and regulator for other CO2 usage if I see the need. Use whatever make you happy, though. (IMG:style_emoticons/brewboard/smile.gif)

Q: Besides a tank and regulator what else do I need?
You will need a "stout faucet" attached to a standard shank on your kegorator. You can get these faucets new from various suppliers (they'll run $50-70 usually) or look for them used on eBay or other such places (I think I paid around $40 for mine with shipping). In addition I recommend getting a "carbonation stone" or "diffusion stone" if you want to carbonated with beer gas (I will cover this below). I use a .5 micron stone because I figure the finer the bubbles the better. The cheapest I've seen them is around $15 at St. Pats or More Beer; I've seen them at various other homebrew suppliers for a bit more. Also you'll need other basic kegging supplies: hoses, clamps, disconnects, etc. (If you aren't familiar with all these things, I suggest some further research on the board).

Q: Can I carbonate with beer gas?
Yes, you can. But no, you do not have to. Beer gas is more costly than CO2, so some people choose to carbonate their beer ahead of time for beer gas usage. Keeping in mind that beer being served on beer gas only has 1.2(usually) volumes of dissolved CO2, which is less that what most beer drinkers are used, you can either add a corrected amount of priming sugar to the keg to naturally carbonate and achieve the proper volumes of CO2 (there are priming calculators out there you can utilize if you decide to go this route) or force carbonate with your CO2 system to whatever level you want. I suggest setting your regulator to the proper pressure to achieve the desired volumes of CO2 at the given temperature. (Again there are charts out there for this purpose; if this concept is over your head, review basic force carbonating procedure before attempting.) I choose to use the beer gas to carbonate so you will have to find and tweak the desired amounts for natural or force carbonation on your own if you choose to go that route.

As I only run a single tap on beer gas, the extra cost is worth it to me to carbonate the beer with the mixture, and not have to mess around with naturally carbonating the beer or force carbonating with CO2. I am aware of three methods to carbonate with beer gas, but have only used the carbonation stone route myself. One of the other options is to just to connect the gas to the in post of your keg, this reportedly doesn't work well for getting CO2 to dissolve in the beer because the nitrogen fills up the headspace and doesn't allow for more of the mixture to flow into the keg. Another option is to connect the gas to the out post of your keg and to burp the pressure release valve on the keg to get the gas to bubble through the mixture. This method seems wasteful and inefficient to me.

Instead I use a carbonation stone in the keg. My stone has a 1/4" barb on it that I attach to a piece of 1/4" ID tubing which is then slipped onto the gas in dip tub inside your keg (cut the tubing length to allow the stone to sit on the bottom of the keg). Sanitize this setup and your keg properly (I use Star San). Once the beer is racked into the keg, place it into your keggerator and connect the gas. The diffusion stone creates a fine mist of bubbles that are more readily adsorbed into the beer. In my experience using this system, the beer will usually be properly carbonated by the time it has cooled down to serving temp.

I run my beer gas around 28psi with 6ft of beverage tubing, I suggest starting there and tweaking accordingly. Note: Beer line length is of less importance on a beer gas system in comparison to a co2 setup. This is because the pressure drop across the restrictor plate is much larger than the losses due to the beer line, thus changes in line length have much less effect in the overall performance. I still use 6ft on my beer gas tap just to keep things universal in my kegorator.

Q: What style can be served on beer gas?
A: I've had and enjoyed stouts, milds, browns, and cream ales on a nitrogen pour. Some styles in my mind wouldn't lend themselves to the mouthfeel of the pour and I've heard that hop aroma can get scrubbed out but haven't tried pouring a hoppy beer on my system personally. Try whatever beer sounds good to you, but those that I mentioned are a good starting point.

Q: Can I switch a beer between CO2 and beer gas?
A: If you have a beer on beer gas and would like to change it over to a CO2 system and tap, just disconnect the beer gas, purge the keg and connect the CO2. I'd suggest purging again to flush out any remaining nitrogen and then wait for the CO2 to bring the beer up to proper carbonation levels for a CO2 tap. This is possible because you are at a lower carbonation level on the beer gas system and nitrogen doesn't get adsorbed into the beer readily. Note that you will no longer be getting the head and mouthfeel (whether that's good or bad in your mind) as you would on the beer gas system. I wouldn't suggest attempting to switch a beer from CO2 to nitrogen, however, because there will be too many volumes of CO2 in the beer which will cause massive foaming if you try and pour it through a stout tap. Degassing the beer is an option, but not one I'd suggest.

Other Tidbits
Cost: Tank, Regulator, Faucet, Shanks, Carbonation Stone, misc. hardware was around $150 (best recollection) in my case, but will vary greatly depending on where you obtain your supplies and at what cost.

Enjoy! (IMG:style_emoticons/brewboard/smile.gif)
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