DOT Sign Requirements for a Diesel Fuel Tank

Updated March 23, 2017

Diesel fuel is a flammable liquid that cause serious injury if stored inappropriately. The Department of Transportation (DOT) mandates manufacturing specifications for diesel fuel tanks mounted on vehicles. It also requires certain markings designed to facilitate safe use of the tank. The DOT defers to other organisations for sign requirements of diesel fuel storage tanks that are not mounted on a motor vehicle.


On January 1, 2000, the Federal Motor Carrier Safety Administration (FMCSA) was created as a separate office within the U.S. Department of Transportation. The FMCSA's primary task is to reduce accidents, injuries and deaths involving large trucks and buses. To this end, the FMCSA maintains safety and signage requirements for diesel fuel tanks mounted on vehicles.

Liquid Fuel Systems

The requirements for liquid fuel systems are contained in Part 393.67 of the FMCSA regulations and pertain to all tanks manufactured on or after January 1, 1973. The section describes the construction, venting, fill pipe and marking requirements of vehicle-mounted diesel fuel tanks. Some vehicles with a gross vehicle weight over 4536 Kilogram are exempted from the requirements of Part 393.67.


Under (c)(11) of Part 393.67, a fuel tank that is readily visible when installed on a vehicle must be plainly marked with its liquid capacity. The body of the tank must also have a plainly marked warning against filling it with more than 95 per cent of its liquid capacity. The tank must also be permanently and legibly marked with the name of the manufacturer, and the month and year of manufacture. Assuming the tank meets all the requirements of Part 393.67 and other applicable regulations, it must clearly say so with the phrase "Meets all FMCSA requirements."

Nonvehicle Tanks

Diesel storage tanks that are not mounted on vehicles are also required to be designated with appropriate signage. One of the most important is the sign required by Code 704 of the National Fire Protection Association (NFPA), an international non-profit company that provides uniform public safety codes and signs. Under Section 105.5 of the FMCSA regulations, the NFPA is a "competent authority" for the mandating of warning signs for nonvehicle diesel fuel storage tanks.

Code 704

The NFPA Code mandates a fire warning sign consisting of a diamond subdivided into four colour-coded diamonds. Each diamond is filled with a number from 0 to 4 indicating the potential risk of the material described by the sign, with 4 corresponding to severe risk. The blue diamond relates to health risk, the red to flammability and the yellow to instability. Diesel fuel tanks are marked with a "2" for health, a "2" for flammability and a "0" for instability.

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About the Author

Joseph Nicholson is an independent analyst whose publishing achievements include a cover feature for "Futures Magazine" and a recurring column in the monthly newsletter of a private mint. He received a Bachelor of Arts in English from the University of Florida and is currently attending law school in San Francisco.