RICKSHAWS and vans in Karachi, pose a danger to all. The following was narrated by a friend.
While travelling in a rickshaw recently, he saw that the rickshaw driver had a petrol-filled plastic bottle by his side. The plastic bottle was a worn-out mineral water bottle found in every garbage dump in Karachi. This bottle was tied to the back-rest of the driver’s seat, with a fragile and insecure string.
In other words, my friend was sitting less than three feet away from a bomb which could explode at any time, as the petrol level in the bottle was fluctuating widely owing to the condition of our roads. As if, this was not enough, the driver was smoking. When my friend protested, the driver said khair hai. Roughly translated this means don’t worry. Almost every rickshaw in the city has such an arrangement to operate the vehicle. These mobile bombs pose a great risk even to VIPs.
The recent van fire incident in New Karachi, in which ten persons died, was the result of the driver carrying petrol in a bottle, close to the engine carburetor. The reason for this tragedy is simple:
One, the driver faced a thrust as soon as the fire broke out (thrust can only be caused by petrol-driven explosions); and two, the fire victims were mainly women and children, as had no time to escape the burning van, indicating a petrol plastic bottle explosion.
Petrol is dangerous because it is highly volatile. Its fumes are capable of ignition up to 12 feet away from a fire source. It can float on water and spread long distances, causing widespread devastation.
The flashpoint of petrol is minus 23 degrees Celsius which enables it to catch fire instantly.
Petrol itself does not burn. It is the mixture of its vapours and air that burns. At normal room temperatures, petrol can give off enough vapour to form a burnable mixture with air. Petrol-fuelled fires burn very fast and give off a lot of heat and often clouds of thick, black, toxic smoke.
The lower flammable limit or lower explosive limit (LFL or LEL) of petrol is 1.4 per cent; the upper flammable limit or upper explosive limit (UFL or UEL) is 7.6 per cent. This means that petrol can be ignited when it is in the air at levels between 1.4 and 7.6 per cent.
Vapours from petrol can flow from open liquid containers and are heavier than air. If this vapour trail contacts an ignition source, the fire produced can flash back to the petrol container even if the petrol giving off the vapour and the ignition source are hundreds of feet apart.
F. H. Mughal
Published in Dawn, January 28th, 2020