Before removing fittings or hoses from an air brake system, it is important to ensure the air pressure is what?

Before removing fittings or hoses from an air brake system, ensuring that the air pressure is drained is crucial for safety and proper maintenance. The air brake system operates under significant pressure, and if fittings or hoses are removed while the system is still pressurized, it can result in a sudden release of air. This can lead to uncontrolled movement of components, potential injury to the person working on the system, or damage to the components. Draining the air pressure minimizes these risks by allowing work to be completed safely and effectively.

Maintaining, increasing the pressure, or simply checking for leaks while the system is under pressure can create hazardous situations and is not a safe practice before beginning any maintenance work on the system. Draining the air ensures that you can safely access the fittings or hoses without the risk of air pressure affecting your actions.