Draught Beer

How does draught beer work

Anyone who enjoys beer, enjoys the freshness and crispness of draft beer over bottled one.

The system involved in draft beer storage and dispensing plays a major role in maintaining the quality and serving beer at the right temperature.

Let’s learn about each of the components involved in our favourite craft beer’s journey from keg to glass.


Keg is a small barrel in sized such as 20L, 30L and 50L. Today’s beer kegs are made of stainless steel though food grade plastic is becoming common place.
Kegs, with a valve guarding the single opening, are used for storing, transporting and dispensing beer. A narrow tube, called a spear, runs from the mouth to the bottom and is the outlet for the beer.
The keg bottoms are shaped as shallow wells to pump out as maximum beer.

Keg Coupler

This is the key that fits the valve of the keg. There are as many kinds of couplers as there are valves – called systems each forming a perfect lock-key combination.

The keg coupler connects the gas and beer lines to the keg through which the pressurised gas is pumped in and beer is pushed out into the beer line.

Gas supply components – cylinder, regulator and gas line
The cylinder contains the gas, usually CO2, but some beers line Guinness Draught use a combination of Nitrogen and CO2 which is to be sent into the keg for carbonizing and pushing the beer into the spear. The spear has a beer line attached at the other end.

The regulator lets us set the optimum pressure for pouring out beer perfectly without too much froth or falling flat. This depends on the length of the beer line.

Gas line is the hose carrying the gas from cylinder to the keg coupler at the set pressure. The gas hose should be secured well with clamps to avoid any leaks.

Beer line

Beer line supplies beer from keg to the tap. Longer beer lines are used when kegs are placed at a farther distance and the CO2 pressure needs to be adjusted accordingly for that perfect pour.

Cooling system

For long-draw use, it is essential to use a cooling system that holds the desired beer temperature from keg to tap. Kegs are placed inside a cold room (a refrigerator for kegs) and cold air or chilled glycol lines running along the beer lines are used for this purpose. These lines are bundled together inside an insulating sheath.


Tower is the largest component of the system that we see, either sitting on the counter or mounted on the wall. It serves the dual purpose of styling and containing the beer and cooling lines that maintain the temperature without exposing to the outer environment.

The Tap

Taps are the final contact point of the system before the beer is poured out for serving. It directs the flow of the beer.