What is the purpose of the alcohol evaporator in some air brake systems?

Some air brake systems include an alcohol evaporator, especially in cold climates. The evaporator slowly introduces methyl alcohol into the air supply during winter operation. The alcohol mixes with any moisture in the system and lowers its freezing point, preventing ice from blocking lines or valves in freezing weather. The driver must check the alcohol level regularly during cold weather and refill as needed. Modern trucks rely more on air dryers (which remove moisture from compressed air before it reaches the tanks) than on alcohol evaporators, but both still exist on the road. Either way, daily draining of the air tanks remains essential.