Braking systems used in commercial vehicles normally use air generated by on-board compressors. Air Dryers are designed to take water vapor out of an air compressor system. Excessive water in compressed air, in either the liquid or vapor phase, can cause a variety of operational problems for braking systems. Moisture can cause corrosion in lines and equipment, reduced braking efficiency and potentially failure in braking systems. Air Dryers effectively removes moisture from the compressed air system and delivers clean, dry air to the brakes.