BLEVE Training Video - Safety Engineering Network (SAFTENG)

A video on BLEVE (boiling liquid expanding vapour explosion) is available at the link below.
BLEVE Training Video Part 1 - EXCELLENT Info - Safety Engineering Network (SAFTENG)
BLEVE Training Video Part 2 - EXCELLENT info - Safety Engineering Network (SAFTENG)

http://www.safteng.net/index.php?option=com_content&view=article&id=1038&Itemid=178 (Part 1)
http://www.safteng.net/index.php?option=com_content&view=article&id=1037%3Ableve-tests-results-1-excellent-info-&catid=52%3Aemergency-response&Itemid=178 (Part 2)
LINK

The video explains about the phenomena of BLEVE, the fire ball radii, the safe distance for emergency responders. We will understand that the safe distance for emergency responders is FOUR times the fireball radius with minimum distance at 90 m. For a 400 lit capacity tank, the fireball radius can be 18 m. We also learn that as the capacity of the flammable storage tank increases by a factor of 10, the fire ball radius doubles. The evacuation distances can be taken as 20 times the fireball radius.

However, these distances are not exact as there are instances of explosion fragments travelling more than 20 times fireball radius. During the incident at New Mexico in 1984, a fragment weighing about 20 T travelled 1200 m.

The water required to cool the exposed hot surfaces 10 lpm/sq.m. It may be noted that inspite of all efforts, if there is whistle/jet engine sound from valves, it is indication of over pressurization inside and all emergency responders should stop their activities and move to safe distances.

Some people assume that BLEVE is possible only with flammable substances. But, as the video explains, BLEVE is possible with any substance that leads to vaporization and pressure rise during external heating/impact and the container rupture leads to BLEVE. Fireball is the result if the substance inside is flammable.

Note: Literature gives following equations:

Fireball radius, R (meters) = 29 M^1/3  where M is mass of flammable in the fireball in tonnes
Fireball duration, t (seconds) = 4.5 M^1/3

Most likely distance for 3^rd degree burns = 80 M^0.42 meters

Maximum distance for 3^rd degree burns = 130 M^0.42 meters

Most likely distance for 2^nd degree burns = 150 M^0.42 meters

Maximum distance for 2^nd degree burns = 240 M^0.42 meters

The heat radiation intensity from the fireball can cause damage to human beings and property. From the literature, it can be seen that 12.5 kw/sq.m heat intensity can be fatal, 8.5 kw/sq.m can cause 1^st degree burns whereas solar radiation gives 0.6 kw/sq.m

Lathe machine accident

A news paper report about 10 days ago mentioned about death of a sweeper near lathe machine in an engineering work shop. The lady sweeper was hit by pieces of drill bit that broke while threading a job piece on the lathe. It appears that excessive force was applied to do threading by the operator. While the woman died at the spot, the operator received serious injuries. This accident reminds about the need for job hazard analysis, proper training and supervision in any work.