A liquid hydrogen tank car, also called liquid hydrogen tank wagon or liquid hydrogen tanker wagon is a railroad tank car designed to carry cryogenic liquid hydrogen (LH2).
LH2 tank cars with a capacity of 17,000 pounds (7,711 kg) are used for transcontinental transport.
[1][2] The pressure within the tank is 25 psi (170 kPa) or lower[3][4] with a temperature below 20.27 K (−423.17 °F or −252.87 °C) and a boil-off rate of 0.3% to 0.6% per day[5] The tank is double walled like a vacuum flask with multi-layer insulation, with the valves and fittings enclosed in a cabinet at the lower side or end of the car.
Cryogenic liquid tank cars in the USA are classified as follows:[6]