49 CFR 174.300 - Special handling requirements.
(a) Class 3 (flammable liquid) materials may not be loaded, transported, or stored in a rail car equipped with any type of lighted heater or open-flame device, or in a rail car equipped with any apparatus or mechanism utilizing an internal combustion engine in its operation.
(b) A truck body or trailer which is loaded with a Class 3 (flammable liquid) materials and equipped with a lighted heater or any automatic heating or refrigerating apparatus may not be loaded on a flatcar except as provided in paragraph (c) of this section.
(1) The lading space is not equipped with any electrical apparatus that is not non-sparking or explosion-proof;
(2) There is no combustion apparatus in the lading space;
(3) There is no connection for the return of air from the lading space to any combustion apparatus; and
(4) The heating system conforms to § 393.77 of this title and does not heat any part of the lading over 54 °C (129 °F).
(d) Metal barrels or drums containing Class 3 (flammable liquid) materials may be transported in a steel gondola or flatcar or in a stock car. However, they may not be transported in a hopper bottom car.