When are you allowed to haul Class 1 (explosives), Division 2.1 (flammable gases), or Class 3 (flammable liquids) in a transport unit equipped with a cargo heater?

The scenario described pertains to the transportation of hazardous materials, particularly those that are highly flammable or explosive. For safety reasons, it is essential to ensure that no additional sources of ignition or heat are present while transporting such dangerous goods.

Choosing to haul Class 1 (explosives), Division 2.1 (flammable gases), or Class 3 (flammable liquids) with a cargo heater requires specific safety protocols to be followed. The requirement to drain the cargo heater or remove its fuel tank and disconnect the power source is crucial. This is because any operational heater can pose a risk of igniting flammable materials due to heat generation, even if indirect.

This safety regulation exists to minimize the risk of accidents during transport, as the presence of an operational heater could lead to combustion. Therefore, the correct choice emphasizes that ensuring all potential ignition sources are eliminated is a fundamental part of safely transporting hazardous materials.