Blended Gas Systems

Foamy beer is caused by the use of 100% carbon dioxide as a dispense gas in draft systems. By using solely CO2 to pressurize the beer, the total concentration of CO2 in the beer skyrockets, creating foamy beer from the taps. This is manifested as excess head, which is poured out into the tray by the bartender as wasted product. It also creates foamy residue in the keg, meaning that an additional 5% of each keg’s beer is wasted. Finally, the greatest offense of foamy beer is to the customer. Excess head that must be poured out spills over the side of the glass, making it wet and sticky. Furthermore, the raised carbon dioxide content distorts the flavor of the beer, causing it to taste sharp.

Using the proper gas mixture is one of the most important factors that influence pouring a great pint of beer. All draft beers are brewed with a certain amount of carbon dioxide dissolved into the beer and it is important to maintain that level of CO2. A 75% nitrogen and 25% CO2 for “nitrogenated” beers like Guinness, Kilkenny, Caffrey’s, etc. which have a relatively low carbonation content (1.2 volumes) and a 50% N2 and 50% CO2 for domestic and craft beers which have a higher CO2 content (approx 2.5 volumes). Maintaining the carbonation content in beer allows you to pour the proper “2 finger” head on every beer from the top to the bottom of each keg resulting in increased yields and profits for your establishment.

Nitrogen (N2) is the perfect choice as a second gas for several reasons. Many beers use nitrogen as an ingredient. The best-known example and the originator of the concept is Guinness Stout on draft. The Guinness brewers go to great pains to dissolve nitrogen in the beer, which improves the quality of the head. Nitrogen (N2) is the ingredient responsible for the “whipped cream-like” foam in the Guinness and other beers like Kilkenny, Boddingtons, Caffrey’s and Murphy’s Stout.

N2, in the right proportion, is required in the gas used to push these beers. Without it, the dissolved N2 would come out of solution and these beers would not be the same. Nitrogen is one hundred times harder to dissolve in beer than CO2. While this is a challenge for the brewers mentioned above, it makes N2 a good choice for dispensing “normally carbonated” beers. N2 is not readily absorbed, does not react chemically under normal circumstances and will not affect beer flavors. N2 is 78% of the air we breathe, making it safer and readily available. Blended Gas Dispense Systems (aka nitrogen generators) filter relatively pure N2 from air and can be a very economical source of Nitrogen. They can be built or used with a blending device and a CO2 source to provide all the gas for any bar or facility.

Flat beer is caused by distribution methods which use compressed air or the improper mix of beer gas (25% CO2). A 25% CO2 mix does not have enough CO2 for proper dispense of most non-nitrogenated (domestic) draught beers, causing beer to go flat. Flat beer is wasteful because you are putting extra (poor quality) beer in every glass. An ideal 5/8″ head is the equivalent of 4% of a pint, so by pouring flat beer your bar loses 4% of the beer revenue. Air is one of beer’s worst enemies; it begins to destroy the product immediately on contact. The oxygen content of the air acts as a flavor contagion, contaminating the drink with the flavors that the air has been exposed to – every flavor in the room. Additionally, air contributes to the growth of several organic contaminates, and requires more frequent line cleaning. Serving your beer with air is the equivalent to pouring a pint, setting it down, and then drinking it the next day!