When loading or unloading Class 1 (explosives), what must you do?

When dealing with Class 1 materials, which are explosives, safety is the paramount concern. Therefore, the proper procedure during the loading or unloading of these materials requires that you turn the vehicle engine off and drain the cargo heater fuel tanks. This is crucial because an operating engine can produce sparks or heat that could ignite an explosive substance. Additionally, draining fuel tanks minimizes the risk of a fire should an incident occur during the handling of these hazardous materials. This precaution is part of the broader set of regulations and safety practices designed to mitigate risks associated with transporting explosives.

The other choices do not align with safe practices for handling explosives. Keeping the vehicle running can increase the risk of ignition; using a forklift could potentially be unsafe depending on the situation and surroundings, and keeping the loading area unmarked could create confusion or indicate a lack of safety measures in place. Proper signage and a clear area for loading are critical for maintaining safety. Therefore, turning off the engine and draining the fuel tanks are necessary actions for preventing accidents when handling Class 1 materials.