What type of draft system utilizes direct exposure to a cooling source?

The type of draft system that utilizes direct exposure to a cooling source is known as a direct draw system. This system draws beer directly from a keg located within a cooler, where it is kept at a consistent, low temperature. The cooling from the refrigeration unit in the cooler directly maintains the beer's temperature as it travels through the lines to the tap.

In a direct draw setup, the beer line is typically short, which minimizes the amount of time the beer can warm up before being served, ensuring that customers receive a cold pint. This method is quite effective for bars or venues with a limited selection of draft beers that are available on tap due to its efficiency and simplicity.

Other systems mentioned, like glycol cooled and air-cooled, utilize indirect methods of cooling. Glycol systems circulate a cooled glycol mixture through the beer lines, while air-cooled systems rely on ambient air from the installation location. Pressure regulated systems focus on maintaining consistent serving pressure but do not pertain directly to the cooling mechanism used for refrigeration. Thus, direct draw is the most straightforward type of draft system where cooling is directly tied to the source holding the beer.