Air Dryers for Trucks and Motor Coaches
Air dryers are installed between the air compressor and the "wet tank" on commercial trucks and motor coaches. Their purpose is to filter out water vapor, oil vapor, and other contaminants before they can reach the air tanks and valves. This helps prevent freeze-up during the winter and extends the life of air valves.
Most air dryers feature a replaceable desiccant cartridge to make maintenance easier. Actually, the only one we have seen that doesn't have a desiccant cartridge is the old Haldex Pure Air dryer. The maintenance kits for that dryer come with a bag of desiccant material.
All air dryers come in 12-volt and 24-volt versions. Most air dryers used on over-the-road vehicles in North America are 12-volt models. You'll typically see 24-volt systems on some imported vehicles and heavy equipment.