Fire impinging on a cylinder containing liquefied flammable gases can result in:

• A. The cylinder melting under pressure.
• B. A BLEVE (boiling liquid expanding vapor explosion).
• C. The pressure relief valve closing.
• D. A slow deterioration of the cylinder.

Answer: (B)

When a fire heats a cylinder containing a liquefied flammable gas, the liquid boils and builds up a very high internal pressure. The container is designed to hold gas at pressure, but as heat continues, the rapid vaporization can exceed what the vessel can withstand. If the cylinder walls fail, the pressurized liquid and expanding vapor vent violently, producing a Boiling Liquid Expanding Vapor Explosion, or BLEVE. This explains why fires involving pressurized liquefied gases can be catastrophic: the release is not just a leak, but a violent rupture that can project fragments and ignite surrounding fuel.

The other possibilities don’t fit the dynamics of a fire. A cylinder melting under pressure isn’t the typical failure mode here; pressure relief valves are meant to vent to prevent overpressure, and in a real fire they may open rather than close. A slow deterioration would not account for the rapid, energetic event characteristic of a BLEVE.