You have loaded a hazardous material into a cargo tank. Before moving the car, what should you do?

Close all manholes and valves before moving a tank of hazardous materials, no matter how small the amount in the tank or how short the distance. Manholes and valves must be closed to prevent leaks. It is illegal to move a cargo tank with open valves or covers unless it is empty according to CFR, Title 49 section 173.29. [Commercial Driver Handbook]