The discovery of fire is one of the earliest human discoveries. The controlled use of fire was an invention of the early Stone Age. This eventually led to change in behaviour of mankind and they started cooking food and obtaining warmth in winter season, feeling secured from harmful insects and beasts and expanded their activity in dark hours of night. The making of fire is a boon for human kind but it is equally dangerous. “Fire is a good servant but bad master” an old English saying reflects the nature of fire i.e. an uncontrolled fire can prove to be disastrous bringing every thing into ashes that comes on its way.
Let us first explain what is fire? Chemically fire is a rapid exothermic oxidation reaction with an emission of light. The mechanism whereby fire initially starts can be best understood by fire triangle viz. fire is an outcome of three elements namely Fuel, Heat and Oxygen. Fire can be started by initially supplying heat which is energy in a kinetic form of molecular motion, once started fire produces heat from the free radical reaction. Sustainable fire is possible only in the ample presence of fuel and oxygen, here fuel can be defined as anything either organic or inorganic and is capable of burning. The destructiveness of fire is the direct result of heat generation which can even melt steel bars. If the fire is uncontrolled then a chain reaction starts, where the heat initially appears, further increases the rate of fire and, therefore, we can say that the transfer of heat is the main factor for controlling the spread of fire. To restrict the spread of fire the transfer of heat must be stopped immediately. The transfer of heat can take place either by means of Conduction, Convection and Radiation process viz. through solid materials (conduction), by air motion (convection) and without any medium (radiation).
Unfortunately, not all the time safety precautions work and unwanted fire accidents happen very often. When undesirable and uncontrolled fire appears then it is necessary to extinguish it immediately in order to minimize the loss. The process of fire extinguishing can be performed in three ways namely Starvation, Smothering and Cooling. Referring back to the fire triangle, we can see that if any of the elements is removed then fire can be extinguished easily. Employing this simple philosophy, we can elaborate starvation as removing fuel/ combustible material from near vicinity of fire. Likewise, when supply of oxygen or any other oxidizing agent responsible for fire is eliminated then it falls under the smothering process. Lastly, the very logical one is the cooling process. Obviously if temperature is lowered then the fire can be extinguished easily. Following chart represents fire classification and its corresponding extinguisher type.
In order to use a fire extinguisher one has to memorize the acronym PASS which stands for Pull, Aim, Squeeze and Sweep. Pull the pin of fire extinguisher rigidly; this will allow you to discharge the extinguisher; next Aim at the base of the fire so that fuel that is burning can be eliminated. When you set yourself in this position then Squeeze the top handle and with the release of pressurized agent Sweep from side to side i.e. Start using the extinguisher from a safe distance and then slowly move forward.
The National Fire Protection Association (NFPA) is an international organization that creates and maintains standards and codes for usage and adoption by local governments. There are approximately over 300 codes and publications available for building construction and useful resources for fire fighters engaged in hazardous materials and rescue response etc. In Pakistan when it comes to making and implementing fire safety laws then no hope appears in near future and generally the occurrence of fire accidents is unreasonably accounted as divine function. The basic structure of the National Fire Safety Policy for Pakistan (NFSPP) has been finalized and is awaited to be implemented as Fire and Safety Act. There is no any clear policy/ guidelines to avoid fire accidents and respond to emergencies which often lead to total chaos, mismanagement and lack of coordination. The metropolitan cities like Islamabad, Lahore and Karachi have been witnessing fire incidents frequently but the basic factors mostly remain a secret or usually termed as electric short circuit. In order to save lives and minimize the loss of property there should be clear laws and regulations and it should encompass all the stakeholders. The building control authority at provincial level has to keep an eye on faulty and dangerous constructions in addition to verifying implementation of safe/ emergency exits in new constructions. Meanwhile, the civil defense department should introduce programmes that can promote general public awareness about fire safety and fire extinguishing techniques. The National Institute of Fire Technology in Islamabad is providing its services in this field and public/ private sector industries must educate and train their personnel and take advantage from this institute.
The writer is the Sr. Engineer (Electrical) in the Karachi Nuclear Power Plant.
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