How long can an LPG cylinder exposed to direct flame in the upper vapor space be subject to BLEVE?

A liquefied petroleum gas (LPG) cylinder that is exposed to direct flame can experience a boiling liquid expanding vapor explosion (BLEVE) if the flame affects the upper vapor space of the cylinder. The correct duration for this exposure, which can lead to catastrophic failure, is up to 10 minutes.

In the context of BLEVE, when a cylinder is heated, the pressure inside the cylinder rises as the temperature of the vapor increases. If the cylinder remains in direct flame long enough, typically around 10 minutes, the heat can cause the safety relief valve to fail or malfunction, leading to overpressure or failure of the cylinder itself. Once this failure occurs, the sudden release of pressurized gas and liquid can result in a BLEVE.

Understanding this time frame is crucial for fire service personnel when strategizing to safely manage LPG cylinder fires. Various safety protocols and tactical decisions revolve around this timeframe to minimize danger to firefighters and civilians, making the knowledge of BLEVE potential critical for incident command and on-scene decision-making.