Which cargo tank is identified as a "DOT 407"?

The designation "DOT 407" refers specifically to a type of low pressure cargo tank as defined by the Department of Transportation regulations. These tanks are built to transport hazardous materials that are not subject to high pressure, typically containing liquids that can be transported at pressures of up to 40 psi.

Low pressure cargo tanks are characterized by their cylindrical shape with elliptical or rounded ends. They are designed to safely carry liquid chemicals, including certain types of fuels and industrial liquids, requiring less stringent structural integrity than pressure tanks. The designation indicates specific construction requirements, such as reinforcement and testing standards to ensure safety during transport.

The other options do not accurately describe what a DOT 407 tank is. Pressure cargo tanks (which are designed to hold materials under higher pressure) and refrigerated cargo tanks (which maintain low temperatures for certain cargoes) have different specifications and applications, and transportable tanks encompass a wider range of configurations beyond just low pressure specifications. Thus, the identification of DOT 407 specifically ties back to its functionality and regulatory classification as a low pressure cargo tank.