A tanker designed to carry flammable liquids, class B poisons, and liquid food products with a vapor pressure of 4 psi is a

• A. MC206/DOT406
• B. MC306/DOT406
• C. DOT407
• D. MC331

Answer: (B)

This question tests matching the tank design to the vapor pressure of the cargo. A vapor pressure of 4 psi indicates a low-pressure, non-pressurized service. The standard design for hauling flammable liquids, some poisons, and liquid foods under that low-pressure condition is the MC-306/DOT-406 cargo tank. This type is built for liquids that don’t require high-pressure containment, while still providing the necessary safety and cleanliness for diverse contents like edible liquids. Other tank designs are tied to higher-pressure services or different cargo profiles, so they aren’t the right fit for a liquid with only 4 psi of vapor pressure. Hence, MC-306/DOT-406 is the correct designation.