At what pressure do pressure rail cars start at?

• A. 20 Psi
• B. 25 Psi
• C. 30 Psi
• D. 50 Psi

Answer: (B)

Pressure rail cars are designed to carry cargo under pressure, so there is a defined minimum internal pressure that classifies them as pressurized. The starting point for these cars is twenty-five pounds per square inch. This value is important because it tells responders that the car operates under pressure and should be treated accordingly—venting, pressure relief devices, and safety precautions all hinge on recognizing that the car is not at atmospheric pressure.

In practice, actual contents can be higher than this minimum, but twenty-five psi marks the threshold that distinguishes a pressure rail car from a non-pressure tank car. So the correct interpretation is that these cars begin at twenty-five psi, guiding how you approach containment, ventilation, and protective actions.