Why must air tanks be drained?

Air tanks must be drained primarily to remove moisture and oil that can accumulate inside the tank. Moisture is a byproduct of compressed air, and when air is compressed, it tends to cool, leading to condensation. This moisture, if not drained, can lead to corrosion within the tank and the brake system, potentially causing brake failure and other serious issues. Additionally, oil can enter the air system from the compressor, and its presence can harm the components of the braking system as well. Therefore, regular draining of the air tanks is crucial to ensure the longevity and effectiveness of the air brakes, promoting safe operation of the vehicle.