Final answer:
Air tanks must be drained to release oil and water buildup, which helps to prevent corrosion and maintain system efficiency. Additionally, it aids in checking for leaks and is part of safety inspection routines.
Step-by-step explanation:
Air tanks, such as the ones used for various applications including industrial and medical or even in vehicles like trucks, need to be drained for a few reasons. Primarily, they must be drained to release oil and water buildup that accumulates over time due to the condensation process that takes place when compressing air. This maintenance is crucial to prevent corrosion and maintain system efficiency. Additionally, draining tanks periodically can also help with checking for leaks and ensuring that the overall system is working correctly, ensuring safety and functionality. For vehicles, this process is a part of regular pre-trip inspections to ensure the air brake system is functioning properly.