What is the pressure usually below for a low pressure tank car?

The correct answer indicates that a low-pressure tank car typically operates with a pressure below 25 psi. Low-pressure tank cars are designed to transport liquefied gases that do not require high pressure for containment. The classification of these tank cars typically includes those that maintain their contents in liquid form with relatively low internal pressures, which are generally accepted to be below 25 psi.

Understanding the parameters around tank car pressure is crucial for safety practices in emergency response situations. Knowing that pressures above this level indicate a transition to higher pressure classifications helps responders assess the potential hazards associated with a tank car incident, as high-pressure tanks present different risks and require different emergency handling techniques compared to low-pressure tanks.

In essence, identifying the threshold of low pressure as below 25 psi informs responders about the necessary precautions and appropriate actions to take when dealing with such vehicles.