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Each year, thousands of fire incidents occur in workplaces resulting to thousands of injuries, deaths and material losses. Many of these incidents go unreported. Fires not only ruin and take life but most of the time companies never fully recover from their effects. Some typical consequences of workplace fires are; - Injury or death of employees, customers, visitors or members of surrounding community. - Disruption to production and supply of goods. - Management time lost. - Prosecution/fines and increased premiums. - Loss of plant, product and/or information. - Damage to the environment. Common sources of fire risk Many work places have equipment, products, materials and processes which have the potential to ignite and propagate a fire. Some behaviours such as smoking and arson can also lead to fire incidents. Fire Triangle For a fire to start and propagate three things are required; heat, oxygen and fuel. A fire triangle is a simple model which helps in understanding the necessary ingredients for fire. When these elements are present in the right mixture, fire will naturally occur. - Heat- can be from a naked flame, a spark from equipment or electricity or a hot surface. - Fuel - these are flammable materials and fluids such as paper, wood, oil, petrol, plastics, cloth and gas among many others. - Oxygen - this is available in the surrounding air. Fire safety, at its most basic, is based upon the principle of keeping fuel sources and ignition sources separate. In addition, taking away any of the components of the fire triangle will extinguish the fire. Fire Propagation Fire spreads through the transmission of heat according to the laws of physics in one of the following ways: Conduction This is the transmission of heat along a solid body. Conducted heat can travel through walls, floors and ceilings, thereby spreading fire to adjacent rooms. Metals have a high thermal conductivity and therefore they pose a greater risk of propagating fires than most other materials. Convection This involves the mass movement of a hotter less dense gas through its cooler denser surroundings. As hot air rises, heat is transferred to any objects that it passes over and to the colder air surrounding it. Radiation This is the transfer of energy as electromagnetic waves. This does not heat up the atmosphere that it passes through but does heat solids and liquids that it lands on. Radiant heat can therefore be transmitted to adjacent buildings if they are not shielded from the fire, even though they may be some distance away. Radiant heat passes through glass easily and buildings with many or large windows are more likely to spread fire by radiation to neighbouring properties. Fire can also be propagated physically through the collapse of hot or burning material, the transport of burning debris in the updraft of a fire, the flow of burning liquids either down slopes or by pressure from extinguisher jets. Fire Prevention To prevent a fire, the elements of the fire triangle must be kept separate. Avoiding these elements from coming together, fire will be prevented. This can be achieved by the following actions; - Keeping combustible materials (fuels) as low as reasonably practical. - Good housekeeping. - Strictly controlling the use and storage of flammable liquids and keeping to the minimum quantities withdrawn from flammable liquids stores. - Storing highly flammable items such as matches or disposable lighters in a separate fire resisting area. - Securing in the upright position all compressed gas cylinders in use - e.g. oxygen, acetylene, propane (LPG) etc. - Enhancing security measures such as CCTV surveillance, intruder detection systems, good lighting and use of fire resistance doors among others - Thorough testing and inspecting all electrical systems comprising transformers, switchgear, distribution wiring and end user equipment at regular intervals as part of planned preventative maintenance. - Making sure that all electrical installation and maintenance work are always conducted by authorised competent persons. - Taking extreme care not to overload electrical supplies and ensuring that all electrical defects observed by employees are reported and rectified immediately. - Establishing a register of all portable electrical equipment from which an inspection of all equipment at intervals should be conducted. All equipment used by contractors should be similarly logged and inspected before use on site. - Properly isolating all electrical equipment and services when not in use.
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