CDM | Centre for Disaster Management (Haryana Institute of Public Administration)



Information

Fire is a very good servant, but, a very bad master. As long as fire is under our control, it serves a lot of useful purposes for us, but, once it goes out of our control, it can create a lot of destruction. However, despite the presence of fire safety measures, the occurrence of accidents is oftentimes inevitable. It is this combination (of good servant and bad master), which is dangerous. Because of the useful purposes that it serves, people keep sources of fire in/around their houses/workplace. And, these sources could sometimes result in "undesired" fire. Had fire been something, which serves no useful purpose – the number of incidents of fire would have been very less – as people wont keep sources of fire around them.

The most common causes of fire are:

  • Electrical
  • Pantry Area
  • Smoking

  • Electrical

    Incidents of Fire mainly caused due to overloading, short circuit etc.

    As people start staying in a new apartment, or, a new office, they start making modifications to the wall socket outlets – in order to be able to plug in additional apparatus etc. Then, there reaches a time, when the total amount of current drawn from all the sockets together could exceed the rated capacity of the internal wiring. A simple solution to this is - not to make too many changes to the electrical circuitry inside your apartment/work-place. And, any alterations etc. if done, should keep in mind the capacity of the wires used. As time progresses, due to various minor repairs etc. wires might be changed, jumbled up etc., or, the insulation among wires might break down. This might cause some wires to come in contact with each other, and, thus, create a short circuit. This short-circuit can cause a very high current flow through the wires – and, thus causing fires. A simple solution to this is: periodic inspection of the conditions of the wiring, and, taking preventive action, whenever needed. And, install MCBs (Miniature Circuit Breakers), so that any short-circuit would result in immediate disconnection of the current flow.


    Pantry Area Incidents involving cooking gas, cooking oil etc.

    Leakage of cooking gas, accompanied by a spark around the leakage could cause fire. These are typically very dangerous. Sources of sparks could be anything: - a burning item, turning on/off of electrical gadgets/switches etc. The leak itself can be in the gas cylinder itself, the pipeline carrying the gas, the regulator, joints etc. Some simple precautions to be taken for this include:
    Regular inspection of gas pipes, and, timely replacement. No sparks etc. in case there is any trace of LPG smell. LPG itself does not have any odour. A trace odour is put in the LPG – only so that any leakage might be detected. Just like electrical points, turn off gases at multiple points, when not in use, rather than just at the point of usage. While cooking, sometimes, the cooking medium could get overheated, resulting in fire. These are more frequent, but, fortunately - relatively easy to manage (if attended to immediately). A simple precaution to be taken for this is - never let cooking oil etc. unattended, when its being heated, nor, do keep bottles of oil etc. in contact with very hot object, like, hot utensils etc.

    Smoking

    Smoking in/around combustible materials could cause fire, due to hot ashes falling from the cigarette.
    Some simple precautions to be taken include:

    • Don’t smoke in/around bed, sofa etc.
    • When you throw away the cigarette etc. always stub it out
    • Always try to dispose off the cigarette-ash at proper places
Do's and Don't

So, there could be a possibility that many people are not going to take part in fighting against a fire. These people need to evacuate. Hence, there needs to be an evacuation plan in place. This evacuation plan should be in place - before the incident of fire. The evacuation plan should have the following items identified, and, well communicated to everybody: - A command and control structure, which should be effective and operational as soon as a fire is reported - Assembly area - Mechanism and responsibility for head-count etc. In case of a fire, one should never use escalators (irrespective of the height of building which is being evacuated). Escalators could be unreliable – due to failure of electrical circuits which operate it, or, it could have mechanical failure – due to snapping of wires/ropes – causing it to go into a free-fall. At the minimum, there is a high risk of smoke inhalation, as, smoke has a tendency to go up, and, hence, will always try to enter escalator pits – from where, it can go all the way up to the top, without any hindrance. If there is lot of smoke, crawl on the floor. Because of smoke’s tendency to go up, even during very dense smoke conditions, the lower few inches of the ground are expected to be relatively free of smoke. To reduce smoke inhalation, put a wet handkerchief to cover your nose. If there is no water available, use your own saliva to wet a small portion of the handkerchief, and, use that portion to cover your nostrils. If you can go to an open-area (for example uncovered terrace, open ground etc.), there will be no risk of smoke-inhalation. However, use your own judgment if you decide to go to the terrace of a high-rise building. While there will be no risk of smoke-inhalation, rescue efforts could become difficult and is dependent on the level of sophistication that the local fire department has (e.g. access to snorkel, very long ladders-capable of reaching high-rise buildings, rescue-helicopters etc.). Always evacuate in an orderly manner. A building housing 200 or so people (normal, healthy adults) across 3-4 floors with a single exit can easily be evacuated in less than 2-3 minutes if done in an orderly manner. If people push and shove, stampede can occur, causing much more injury, and, it might take much longer to evacuate. Worse: Backing up might be impossible. Say, while, people are evacuating towards an exit, and, its found that – the specific exit is blocked, there might be a need to backup. If the evacuation is not proceeding in an orderly manner, it might not be possible to back-up; as people towards the end of the evacuation queue (who are not aware of the blockage at the exit) will try to push forward, while, those at the front of the queue (who are aware of the blockage) want to back-up. Since, panic might set in, during a fire – thereby clouding people’s thought process and ability to think reasonably, its highly likely that during a fire, people forget these simple tenets, and, in their attempt to rush out, actually create chaos and disorderliness. Thus, its important that regular mock evacuation-drills are carried out. That will cause people to behave in a much more orderly manner – during an actual fire. While evacuating, do a quick survey to see, if there is somebody around you, who might need some assistance, e.g. somebody who is old, too weak, injured, child, any disability etc. If possible, provide assistance to such a person. Even if you yourself are not in a position to provide assistance, at least request for help on this person’s behalf.
If an area is already clear, while, evacuating, close the door behind you. It will serve several purposes:
Will isolate the area, thereby, causing an impediment to the spread of the fire. Will save time for others, who might want to recede the area.
While, you should close the door, lock it only if you are absolutely sure that there is nobody inside. Because, if there was even a single person inside it, and, you have locked it, the chances of that person being rescued is diminished by a huge factor. If you are inside a closed door – with fire outside: Feel the inside of the door with your hand. If the door feels hot, many a times, it might be safer to stay inside. At this time, whether your should stay inside, or, still venture out could be a judgment call, depending on: how long do you expect a rescue team to arrive and/or alternative avenues (e.g. possibility of jumping from the window). If you are on the high floor of room, with windows having strong grills and the local fire-department is not well-equipped/staffed, then, the time that you spend inside the room is actually going against you – as the fire outside becomes more vigorous. If you do decide to stay inside the room, wet towels, bed sheets etc. and put below the doors to prevent smoke etc. from coming inside your room.

Emergency kit

Types Of Fire Extinguishers

  • Water Based
  • Foam Based
  • CO2 Based
  • CFC Based
  • Dry Chemical Based
1. Water Based
These are most effective on Class A fires.
On Class B fires, these are mostly ineffective. This is because, oil/petrol/gasoline etc. being lighter than water continues to float over water, and, thus, it continues to burn. In some cases, use of water based extinguishers on Class B fires could turn out to be injurious also. That is because, as water is thrown over burning fuel, the force due to water-stream could cause burning petrol etc. to be sputtered, and, this hot fuel could cause injury, if it falls on somebody.

On Class C fires, these should never be used. Use of water based extinguishers on Class C fires would surely be fatal. That is because, water is a good conductor of electricity, and, the electric current flows through the water-jet directly into the hands of the person who is holding the water-hose, resulting in immediate electrocution.

The way, these extinguishers work is: As water reaches the burning material – because of the high temperature, it vaporizes. While vaporizing, it extracts the latent heat from the burning element, thereby reducing the temperature. Besides, as it vaporizes, it expands. Usually, the expansion is in the order of 100 times (by volume). The need for higher volume of steam (vaporized water) displaces oxygen from the immediate vicinity of the burning material, thus, cutting off the oxygen supply.

Also, water being non-combustible material also tries to form a coating between the atmosphere (which is supplying the oxygen) and the combustible material.

Thus, it tries to reduce temperature, as well as displace oxygen, thus, attacking two arms of the fire-triangle, while, making a very feeble attack on the third arm also.

2. Foam Based

These are used mostly on Class B fires. It can also be used on Class A fires. These should never be used on Class C fires. The main constituent of foam being water – it can easily prove to be fatal on a Class C fire. Foam being lighter engulfs the burning liquid. By covering the burning liquid, it cuts off the supply of oxygen to the burning material. Besides, the vaporization of water also helps in reduction of temperature – due to extraction of latent heat. The basic principle is thus, similar to Water Based Extinguisher. The only difference is, foam stays above burning oil, thus, trying to engulf it - something that water could not do.

3. CO2 Based

These are mostly used on Class C fires.

It can also be used on Class A and Class B fires.

These kind of extinguishers might also be used to extinguish fires in computers, costly electronic equipments etc. where, usage of water etc. could cause damage to the equipment.

The biggest advantage of these kinds of extinguishers are that it does not leave any residue, smell or mess.

However, usage of these kinds of extinguishers in confined space could result in poisoning. Because, under lack of oxygen, carbon-di-oxide could act as a fuel, and, the resulting gas produced could be carbon-monoxide – which is highly poisonous.

The way these extinguishers work is: A stream of dry-ice (trade name for solidified carbon-di-oxide) is directed towards fire. Dry ice being very cold helps to reduce the temperature. Being heavy, carbon-di-oxide gas settles on the burning equipments, thus blowing away the oxygen – thereby cutting out the availability of oxygen.

Sometimes, the printed circuit boards (PCBs) of these electrical equipments could develop a crack, because the burning material which was hot is suddenly subjected to a very cold temperature (of dry ice). However, having a few cracks on a few boards might be a better choice than using water/foam, which will cause total short-circuit within the electrical circuit.

Carbon-di-oxide based extinguishers have an additional advantage. Being primarily gaseous in nature, the extinguishing agent can easily percolate inside machinery through fine slots (usually provided for ventilation/heat dissipation) on the outer casing of the equipments. So, it can be much more effective in fires which are inside the casing of electronic equipments.

4. CFC Based

These are mostly used on Class C fires.

It can also be used on Class A and Class B fires. The main difference between CO2 Based Extinguisher and CFC based extinguishers is that instead of carbon-di-oxide, it uses some inert gases, like: CFCs. These extinguishers also do not leave any residue, smell or mess. However, these are highly damaging to the environment (because of the tendency of CFCs to deplete the ozone layer). Many variants of CFCs are already banned. Some newer (and, cleaner) variants are already under consideration.

These extinguishers are very costly (both in terms of money as well as impact on environment), and hence, should be used only on very costly, specialty equipments.

The working of these equipments is very simple. They simply displace the oxygen at the burning site. And, these being highly inert gases – would not take part in any chemical reaction (including the process of burning), nor would let the burning material take part in the burning process – thereby extinguishing the fire.

These kind of extinguishers can also be used on metallic fires (Class D). Other extinguishers mentioned earlier could have mixed results on Class D fire, depending on which metal is burning.

5. Dry Chemical Based

These are most commonly used type of extinguishers.

It can be used on Class A, B and C fire. Hence, its popularly also called as ABC type extinguisher. Its impact on Class D fire could be varied, depending on the type of metal being burnt.

It works in the following way:

It stores dry yellowish chemical powder (mono-ammonium phosphate) under pressure of nitrogen gas (or, any other inert gas). When turned on, the dry powder is sprayed with pressure onto the burning material, along with the inert gas. Nitrogen displaces oxygen. The powder itself sits on the burning material – thus removing contact between burning material and its other two arms of fire.

The powder is a non-conductor of electricity – hence, its equally effective on Class C fire.

Using An Extinguisher

So, now that you have decided how to fight a fire, and, what kind of extinguishers to use, lets see, how to use an extinguisher. Most extinguishers are based on PASS System.

  • Pull the Pin on the extinguisher. This pin is kept to prevent accidental discharge while carrying/transporting the extinguishers.
  • Aim the nozzle of the extinguisher at the base of the fire. Its very important that the discharge from the extinguisher is directed towards the base of the fire. Most people make the mistake of directing the extinguishing agent on the fire itself. That’s ineffective. The extinguishing agent should be directed at the base of the fire – where the burning material is located. That is the point, where the fire-triangle is established, which needs to be broken.
  • Squeeze the trigger, so that the extinguishing agent starts flowing out of the cylinder, and, onto the burning material – at the base of the fire.
  • Swipe the nozzle sideways to coat the entire burning material, with the extinguishing agent.
  • “PASS” is an acronym to remember the steps involved – Pull (the pin), Aim (the nozzle), Squeeze (the trigger), Swipe (sideways).