What distinguishes a pressure tank car from a nonpressure tank car?

• A. Pressure tank cars carry liquids at high temperatures
• B. Nonpressure cars can only carry solids
• C. Pressure tank cars carry liquefied compressed gases
• D. Nonpressure cars are used only for gases

Answer: (C)

Pressure tank cars are specifically designed to transport liquefied compressed gases under high pressure, including substances such as propane, butane, and other gases that require a pressurized environment to maintain them in a liquid state. This capability is what primarily differentiates them from nonpressure tank cars.

Nonpressure tank cars, on the other hand, can carry liquids but are not built to withstand the same pressure as pressure tank cars. Therefore, they are typically used for transporting liquids that do not require pressurization. The distinction is crucial for safety and operational reasons because the structural design of pressure tank cars allows them to handle the risks associated with transporting hazardous gases under pressure. Understanding this difference is essential for emergency response and handling of potentially dangerous materials during transport.