Watching fires is not a fun

http://www.dailystar.co.uk/news/latest-news/502597/petrol-station-explode-blast-Russia-Dagestan-multiple-dead-natural-gas-firefighters-police

In the video, it is seen, persons walking aside, not knowing the dangers of such fires. Fragments from explosion can travel great distances and can kill the persons. Thermal radiation from fireball also will be felt at longer distances, the overpressure in the form of pressure waves can lift the equipment/persons off the ground, making them to hit other objects and thus get injured/killed.

BLEVE

In a report (http://www.homernews.com/stories/111611/news_fdef.shtml#.TsiKjT38Kxw), it is mentioned that a fire started in a residential garage eventually led to BLEVE (boiling liquid expanding vapor explosion) and fireball involving a fuel oil tank kept inside the garage. The fireball sucked the oxygen and led to containment of fire. The fire was noticed by a neighbor who cautioned the resident of the house to escape.

Due to this, the tank failed with main tank shooting of 150 feet through a wall into the field, while the tank bottom blew through a steel door. The blown tank flew between fire fighters and nobody suffered even any minor injury.

The wind pushed the flames towards the house from garage and some front portion got burnt.

It is reported that the fire fighters heard venting sound like a jet engine and shortly afterwards, the blast took place.

The panicked owner could not tell the fire fighters about the fuel tank inside, though she told about other flammables inside. Fire fighters were unable to see the tank because of flames and heat.

There are no state fire codes to prohibit storage of fuel tanks in residential properties, though such codes exist for commercial and multi-dwelling units.

The Chief of Fire Service is not sure of proper working of vent. It is said that the fuel oil tanks are not designed to hold pressure. It appears that the fuel oil tank is having oil only to some level as per the visible line showing where it was empty.

The Chief advised to keep the oil to the full so that the heat can be absorbed and that vapor build up will be less inside the tank thus preventing pressure rise and explosion. He also feels that the tanks should be kept in open area with ventilation instead of keeping them inside.

From this incident, we can draw following lessons:

1. Flammable storage tanks should be kept outside with proper ventilation and fencing.
2. It should have proper vent relief.
3. It should have properly designed water sprinkler system.
4. It should be fenced to prevent others coming closer to it.
5. The whistle/jet engine sound from a tank exposed to fire is an indication of blast / explosion / BLEVE in a short time and all people including emergency responders should vacate the area to a safe distance.
6. No other flammable/combustible materials should be stored in the area.
7. The safe distance depends upon the maximum capacity of the storage tanks exposed to fire, the distance up to which blast fragments can travel, the distance up to which thermal radiation from a resulting fire ball can cause first degree burns, the distance up to which the over pressure can cause damage to the glass panes.
8. The name plate containing the details of the contents, capacity, design pressure, safe distance in case of fire along with emergency contact numbers should be displayed at a place easily visible and accessible, away from the storage area.
9. Periodical mock drills should be conducted to take prompt action in a real emergency.

Air receiver blast

There was a blast during the cleaning of gas turbine in a polymers factory that makes cans, jars, etc. It is reported that the the valve of the gas turbine suddenly blew up that caused ripping of roof and fragments caused injury to a woman nearby. As per the news in a local news paper, due to malfunctioning of safety valve on the air receiver, the air receiver exploded. As Monday was holiday for the factory, it is reported that no injuries took place in the factory. It is luck that the person involved in the work is safe though the roof sheets blew off but did not fall on him. It is not known what precautions were taken before taking up the cleaning job, like, i) emptying the vessel and purging with inert gas and then purging with air, ii) positive isolation of all lines leading to and from the tank, iii) checking for presence of flammable concentrations in the tank, iv) checking for oxygen level, v) job hazard analysis, vi) supervision and so on.

As the work was taken up on factory holiday and incident happened, one should be careful when planning such maintenance jobs on holidays it should be ensured that safety work permit is obtained and supervision is provided.