Air Dryers

Air Dryers

General Information

Air dryers have become an increasingly important part of the air brake systems in Heavy Duty vehicles.  They are considered to significantly improve the efficiency and life expectancy of the vehicle's compressed braking system.  

What Does it Do?

When air is compressed, the heat that arises from the process enables a greater amount of moisture to be transferred than the air is normally capable of supporting.  Air dryers are fitted into vehicles air brake systems as a way of removing these moisture particles, mainly oil and water, from the compressed air before they reach the braking system. Without such a process moisture would be able to contaminate the braking system; whilst the air gradually cools it becomes incapable of maintaining high moisture levels and drops the particles onto the brake system components, reducing their efficiency.

For instance, the existence of water can not only lead to the corrosion of  the intrinsic parts of the system but can also lead to the freezing of the braking system in cold weather conditions. This can be extremely dangerous to the functioning of the system, potentially making the brakes work harder and even leading to complete brake failure.

The failure to remove oil from the system can also result in the swelling of brake components, which can reduce their  responsiveness.

How Does it Work?

Air dryers use the most advanced technology to provide clean and dry air to air brake systems. A pre-filter removes large particles from the air whilst the desiccant chamber uses a drying agent to absorb the water and oil molecules. The greater the pressure and the lower the temperature of the air, the more effective the air dryer becomes. Thus, once the air has been initially cooled, air dryers are designed to be able to receive the air at a high pressure to improve effectiveness. Once the dryer has absorbed all the moisture possible it releases the water and oil particles it has collected into the open air; enabling the air dryer to begin to effectively absorb moisture again.

The lifetime of an air dryer is dependent upon the conditions in which it is used. In general, the greater the oil particles in the compressed air the more saturated the air dryer becomes, and the less able it becomes to effectively absorb the remaining moisture particles. This will result in an increased amount of residual water in the bottom of the air dryer and is a sign that the system needs servicing.