What are the key safety risks of bulk propane storage and transport?

What are the key safety risks of bulk propane storage and transport?
Propane's physical properties create distinct hazards. Its boiling point of -42°C means it vaporizes rapidly when released, and at 1.56 times the density of air, it pools in low-lying areas where a single spark can trigger an explosion. The flammable range is wide—2.1% to 9.5% by volume in air. Recent flooding in Arizona dislodged 1,000 propane tanks, turning them into high-kinetic projectiles that could rupture on impact, releasing pressurized liquid that flash-evaporates and forms explosive vapor clouds. Even intact tanks exposed to heat can overpressure and burst. Commercial propane is odorized with mercaptans for leak detection, but in large-scale incidents, relying on smell is insufficient. For industrial buyers, these risks translate into strict storage siting requirements, vapor detection systems, and emergency response protocols that add to operational costs.