A keg coupler is a device that attaches to a keg of beer, tapping into its inner contents. Other beer equipment such as dispensers and faucets can be connected to the coupler, helping to retain the proper carbonation and pressure levels depending on the brew. There are generally six types of keg coupler. Each is typically suited for a certain variety of keg and the formulation of the beer. Manufacturers around the world often sell these couplers to distributors and beer retailers.
The standard types of keg coupler has made it generally convenient to install, without taking up too much time or spilling significant amounts of beer in the process. Most kegs made in North America use one type of valve that allows almost any kind of coupler to be attached. Beer kegs in other parts of the world, however, can feature one of four kinds of valves in which the coupling mechanisms for each are generally different.
In the United States and Canada, a D coupler is often used. The device is typically suited for use with ales, lagers, and stouts, as well as wheat beer. Similar to this variety is the D coupler, except that the stem of the product typically goes further inside the keg. An A coupler is commonly used in Germany for beer with low carbonation, while a G coupler, generally found at pubs in England and Ireland, is often compatible with heavy beer with low carbonation. The U coupler is also often used with beer from these regions as well.
It is generally not difficult to change a keg coupler at the beer line end. Varying configurations of check valves and washers, however, can complicate removal and installation where the gas enters. Gas hoses can often be used with D and S couplers, and be screwed on via a hex nut, while other types may require the removal of the gas line when the coupler is changed.
Some types of keg coupler for draft beer have extra features. They can include foam detectors which shut down as the keg is about to go empty, so foam does not get poured into a glass and does not get mixed with the beer. Keg couplers and related accessories such as screws, check balls, retainers, and safety assemblies can often be purchased online for use in bars as well as homes during gatherings where people drink beer.