Maintaining an air dryer system

Service & Repair Truck Parts and Service Staff January 21, 2014

Compressed air has a variety of uses in today’s commercial vehicles. According to Bendix, it is imperative to proactively maintain air systems to ensure each component operates at peak performance.

This includes the air dryer system and associated valves and reservoirs, the company says.

Inspecting an air dryer system should begin with opening the drain valves on the reservoirs to check for moisture in the system, Bendix says. If moisture is present, technicians should verify that no external air has been applied to the system, and check the air dryer’s service data sheet to confirm that the air dryer is mounted in the correct location with the correct discharge line length.

If external air was applied, Bendix says to then drain all reservoirs and purge tanks, restart the vehicle, and allow system pressure to build to the governor cutout pressure. Techs should then verify the proper system pressure has been reached, and then operate the vehicle normally. Bendix says techs also should recheck for water in the reservoirs after one week.

If an issue with the air dryer mounting or plumbing is encountered, Bendix warns to have it corrected, and ensure the discharge line from the compressor to the air dryer slopes continuously downward to the air dryer inlet, with no water traps.

Bendix also notes to take into account any significant temperature changes within the previous 24 hours. Ambient temperature shifts of greater than 30˚F can cause a temporary accumulation of moisture, the company says. If a significant temperature change occurs, continue to operate the vehicle under normal conditions. The small amount of water that may have condensed due to the temperature shift will be reabsorbed by the dry air once the vehicle is in operation, Bendix says, then check the air system again after one week.

Whether moisture is present in the system or not, Bendix says to check all the air lines for damage such as chafing, and examine the air dryer mounting bolts for tightness and torque as specified in the manufacturer’s service data sheet.

Within the air dryer system, Bendix says there are three key components to monitor: the air dryer cartridge, the purge valve, and the delivery check valve.