The extreme heat that is boiling much of New England today raises another cause for concern: BLEVE, or Boiling Liquid Expanding Vapor Explosion.
Firefighters work to put out a propane tank explosion.The term BLEVE is well known among firefighters and hazardous materials response teams and does not solely refer to propane tanks. BLEVE occurs when the pressure in the tank exceeds that at which the safety relief valve can safely vent the excess pressure into the outside atmosphere. Relief valves are designed to vent tank pressure at a certain flow rate to the outside atmosphere once the pressure inside the propane tank reaches a certain level and will close once the pressure in the tank falls below that level.
In the case of a propane tank, BLEVE can occur when the container is subject to extreme heat, such as in a fire or when subjected to direct, hot sunlight. While the tank is being heated, the liquid propane inside is being heated causing it to expand.
The safety relief valve will open allowing pressure to vent to the outside atmosphere. This escaping gas could ignite if a source of ignition is close by. Or, if the pressure inside the tank grows to a level exceeding that at which the safety relief valve can expel it from the tank, the propane tank may rupture.
Please keep this in mind as our area deals with high temperatures and heat indexes today and for the next several days.