The greatest danger of propane cylinders is _____.

The greatest danger of propane cylinders is a Boiling Liquid Expanding Vapor Explosion (BLEVE). This situation occurs when a propane cylinder is exposed to heat, often due to a fire. The heat increases the pressure inside the cylinder, and if the structural integrity of the cylinder is compromised—due to the high temperature or pre-existing weaknesses—this can lead to a catastrophic failure.

In a BLEVE, the liquid propane rapidly vaporizes, leading to a violent explosion. This type of explosion is particularly dangerous because it can produce high-speed projectiles (the ruptured cylinder) and an extensive fireball resulting from the ignition of the released gas. Understanding this risk is critical for firefighters and responders when they approach incidents involving propane cylinders, as the potential for severe injury and destruction is significantly heightened.

Though other risks such as leakage, explosion in general, and corrosion of the cylinders are important considerations, the specific risk of BLEVE represents the most severe outcome under conditions of heat exposure. This defines it as the greatest danger associated with propane cylinders.