What indicates that a DOT cylinder is overfilled?

The correct choice highlights the importance of monitoring the weight of the cylinder to determine whether it is overfilled. Each DOT cylinder is designed with a specific capacity that indicates the maximum amount of liquid propane it can safely hold. If the weight of the cylinder exceeds the recommended limit, it is a clear indication of overfilling, which poses safety risks such as pressure buildup, leaks, or even potential explosions.

While factors such as the sound of gas escaping or the presence of visible liquid propane can suggest issues, relying on the weight is the most definitive and quantitative method of assessing the state of the cylinder. The color of the gauge can vary and may not be a consistent indicator of overfilling, and thus it is not a reliable measure on its own. Monitoring cylinder weight helps ensure safe handling and compliance with regulations related to propane storage and transportation.