Which cargo tank trucks feature frangible disks and fusible plugs?

The choice of MC 307/407 low pressure carriers as the correct answer is based on their specific design intended to maintain safety during transport. These cargo tank trucks are equipped with frangible disks and fusible plugs that act as safety devices.

Frangible disks are designed to rupture at a predetermined pressure, allowing excess pressure to escape and thereby preventing tank rupture. Fusible plugs, on the other hand, are thermally activated devices that will melt at elevated temperatures, providing an additional safety measure to relieve pressure in the event of a fire. This combination of features is crucial in preventing explosions and catastrophic failures, particularly when transporting materials that could pose a risk if pressurized during an incident.

In contrast, the other types of carriers specified either do not incorporate these safety devices or utilize different safety mechanisms appropriate for their intended cargo and operational pressures. Understanding the characteristics of each type of cargo tank is essential for responders in identifying potential hazards and managing incidents effectively.