Which designation is used for a non-pressure liquid carrier?

• A. MC 331
• B. MC 306/DOT 406
• C. MC 338
• D. MC 312/DOT 412

Answer: (B)

Understanding tank designations helps you know how a tanker is built to carry its contents. Non-pressurized liquid carriers use low-pressure tanks, and the designation that matches this general use is the one for a non-pressurized liquid cargo tank designed to haul flammable liquids.

This designation explicitly identifies a non-pressurized tank used for liquids, distinguishing it from tanks built for high-pressure service, cryogenic (very cold) liquids, or corrosives. The other options describe specialized services: one is for high-pressure liquids, another for cryogenic refrigerated liquids, and another for corrosive liquids in a non-pressurized tank. Since the question asks for a general non-pressure liquid carrier, the non-pressurized liquid designation for flammable liquids fits best.