The air reaches the tiny air sacs (alveoli) in the inner part of the lungs with any dust particles that avoided the defenses in the nose and airways. The air sacs are very important because through them, the body receives oxygen and releases carbon dioxide.
1 A full size keg holds about 15.5 gallons (165 12-oz cups) and is sometimes referred to as a 1/2 keg. 2  The full-size kegs typically start at about $100 for American draft beers. 3  Specialty beers, lagers and ales can cost from $125-$250.
The US beer barrel is officially defined as a volume unit which is equal to 31 gallons. This is why a full keg is named a half barrel, though it has 15.5 gallons. Most brewers use this kind of kegs, so we can make some calculations and answer how many beers are in a keg. One full keg contains: Almost seven 24-racks of 12 oz cans.