Vapor explosion

Frank T. Bodurtha/ Sc D / E. I. du Pont de Nemours and Co., Inc., (retired) Consultant, Frank T. Bodui tha, Inc. (Gas Explosions Unconfined Vapor Cloud Explosions [UVCE.s] and Boiling Liquid Expanding Vapor Explosions [BLEVE.s])... 

Unconfined Vapor Cloud Explosions (UVCEs) and Boiling Liquid Evaporating Vapor Explosions (BLEXT s)... 

UNCONFINED VAPOR CLOUD EXPLOSIONS (UVCEs) AND BOILING LIQUID EXPANDING VAPOR EXPLOSIONS (BLEVEs)... 

The mechanical flame barriers, which are used for explosion isolation of flammable gas and solvent vapor explosions, are veiy susceptible to the action of dirt and, with one exception, are thus not suitable for dust-canying pipelines. The exception involves the rotaiy valve (see Fig. 26-45), which is based on the flame-quenching effect through narrow gaps and is mainly used at product charging and discharging points. 

BLEVE Boiling Liquid Expanding Vapor Explosion... 

Avoid direct sunshine on containment surfaces in hot climates. Direct spills of flammable materials away from pressurized storage vessels to reduce the risk of a boiling liquid expanding vapor explosion (BLEVE). 

Undesired reactions catalyzed by materials of construction or by ancillary materials such as pipe dope and lubricants Boiling liquid, expanding vapor explosions (BLEVEs)... 

A flammable vapor explosion in a vessel initially at atmospheric pressure can create a pressure of 10 atmospheres (NFPA 69, 1992, Section 5-3.3.1). A weak process vessel requires substantial vent area for vapor-air explosion relief. 

At first it was thought that the spheres burst because their relief valves were too small. But later it was realized that the metal in the upper portions of tlie spheres was softened by the heat and lost its strength. Below the liquid level, the boiling liquid kept the metal cool. Incidents such as this one in which a vessel bursts because the metal gets too hot are known as Boiling Liquid Expanding Vapor Explosions or BLEVEs. 

This text is intended to provide an overview of methods for estimating the characteristics of vapor cloud explosions, flash flies, and boiling-liquid-expanding-vapor explosions (BLEVEs) for practicing engineers. The volume summarizes and evaluates all the current information, identifies areas where information is lacking, and describes current and planned research in the field. 

On January 4, 1966, at Feyzin refinery in France, a leak from a propane storage sphere ignited. The fire burned around the vessel and led to boiling liquid expanding vapor explosions. The accident caused eighteen deaths and eighty-one injuries. 

Reid, R. C. 1980. Some theories on boiling liquid expanding vapor explosions. Fire. March 1980 525-526. 

Venart, J. E. S. 1990. The Anatomy of a Boiling Liquid Expanding Vapor Explosion (BLEVE). 24th Annual Loss Prevention Symposium. New Orleans, May 1990. 

Failure followed by inunediate combustion Runaw ay chemical reaction before failure Runaway nuclear reaction before failure BLEVEs (boiling liquidexpanding vapor explosion pressure vessel containing a flash-evaporating liquid) External Heating Immediate combustion after release No combustion after release... 

Unconfincd vapor cloud explosions (UCVEs) Physical vapor explosions ... 

Boiling Liquid-Expanding Vapor Explosions (BLEVE)... 

A boding liquid-expanding vapor explosion occurs when a pressure vessel containing a liquid is heated to a temperature liigh enough to cause tlie metal to lose strength and rupture. The source of tlie heat is nonnally another fire near tlie vessel. The effects of a BLEVE depend on whether tlie liquid in tlie vessel is flammable. If the liquid is flammable, it may eitlier cause a fire, which radiates heat, or fonii a vapor cloud, which could result in a second explosion. 

The three basic types of explosions to be concerned about in the chemical and petrochemical environment are combustion explosions (deflagrations), detonation explosions, and BLE 7Es or boiling-liquid expanding vapor explosions [38]. 

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