Industrial Fire Journal - Fire & Rescue - Hemming Group Ltd
Experimental determination of BLEVE-risk near very large fires in a tunnel with a s prinkler/water mist system
Published:  14 April, 2010

The effectiveness of a sprinkler/water mist system to prevent a BLEVE in a LPG tank truck in a tunnel fire was verified in a series of large scale fire tests in the Runehamar test tunnel in Norway. A full-size LPG tank, partially filled with water, was placed in the tunnel and subjected to a series of large cargo and pool-fires located closely upstream from the tank. The thermal conditions around the tank and the thermal response of both the tank's surface and its bulk were measured and the risk of a BLEVE was predicted from these measurements.

Only when the limits of the water mist system were sought, by purposely delaying the activation time with about 7 minutes, there proved to be a serious risk of a BLEVE. This occurred after 400s in one fire test with a cargo consisting of 720 stacked pallets. In all other tests the fire was extinguished or controlled quickly enough to prevent a BLEVE. Quick detection and extinguishment of the fire was shown to be especially important with a pool fire, due to the fast increase of the temperature around the tank to about 1000oC.