Whenever working on or near air brake systems and components, always observe the following:

1. Before performing any test and/or isolating the air dryer, the vehicle's wheels must be chocked. Never work under a unit supported only by a jack. Always support the vehicle with stands. Block the wheels and make sure the vehicle will not roll before releasing the brakes.

2. Stop engine when working under a vehicle.

3. Never connect or disconnect a hose or line containing air pressure. Never remove a component or a pipe plug unless you are certain all system air pressure has been exhausted.

4. Always wear safety glasses when working with air pressure. Never look directly into air dryer ports.

5. Never exceed recommended working air pressure.

6. Never attempt to disassemble an air dryer until you have read and understood all recommended procedures. Use only proper tools and observe all precautions pertaining to the use of those tools.