DOT 406 is commonly used to transport which product?

• A. Petroleum
• B. Water
• C. Ammonia
• D. Natural gas

Answer: (A)

DOT 406 designates a low‑pressure cargo tank built for flammable liquids that have relatively low vapor pressure, which is why it’s commonly used to haul petroleum products like gasoline and other fuels. These tanks are designed to carry flammable liquids such as gasoline, diesel, or kerosene on highways, prioritizing safe handling of fuels and limited vapor release.

Water wouldn’t require a hazmat‑coded, low‑pressure petroleum tanker since it’s not a flammable hazardous liquid. Ammonia is typically carried in specialized pressurized or refrigerated tanks because of its toxicity and high vapor pressure, not in a standard low‑pressure fuel tanker. Natural gas isn’t transported in highway liquid tankers at all; it’s moved by pipelines or as a compressed or liquefied gas in other types of equipment.