Experimental Fires in Enclosures - Literature review Example

2. Chapter 2 - Literature Review 2.1 Fires in Enclosures Fire is both physical and chemical phenomenon where flame, fuel, air, and surrounding environment interact. Fire development in enclosure such as buildings and houses is different from a fire in open spaces because its growth is affected by the size and shape of the enclosure, increasing temperature and level of oxygen in the enclosure. Fire development in enclosure according to , has different stages – ignition, growth, flashover, fully developed fire, and decay . In terms of fire prevention, these fire development stages suggest that fire cannot start without ignition (exothermic reaction or increase in temperature beyond the ambient generated by flaming match, spark, and other heat sources) and cannot grow without fuel (combustible materials) and oxygen that is available within the enclosure and supplied through vents . Similarly, if the fire actually occurs and grew, it cannot reach flashover if the temperature in the enclosure is below 500 degrees centigrade and radiation below 15 kW/m2. Note that according to , this temperature and radiation increase depends on fuel properties, fuel orientation and position, enclosure geometry, and conditions in the upper part of the enclosure where smoke and gases accumulate. Based on the above information, fire in dwellings can be prevented if the first stage does not occur or growth in the second stage is suppressed early (due to early arrival of fire fighting personnel or with automatic suppression devices) or limited by both fuel properties and quantity, and air through ventilation. In case prevention of first two stages fail, fire spread is likely to occur thus most fire prevention strategies often recommend compartmentation, fire rated doors, and partitions than can help prevent the spread of fire . In summary, as fire requires heat for ignition, the interaction between flame, fuel, and oxygen, and additional amount of fuel and oxygen supply to grow in an enclosure, then most logical approach is to prevent ignition. This is because aside from avoiding the more dangerous stages of fire, separating the heat source from combustible or ignitable materials is easier and more economical to do than installing expensive fire suppression system or fight a fire when it already done a lot of damage. However, since neglect and other unsafe behaviour can happen anytime, it may best to consider at least the first two stages of fire development and install warning devices, fire doors, and remove any potential fuel near heat sources. 2.2 Residential Fires and the Fatal Effects of Fires There are several major causes of fires in homes and these include cooking and heating equipment, smoke-material, electrical fire, candle fires, children playing with fire, intentional fires and others. Similarly, the location where the fire starts varies and these include fires that began with mattresses and bedding, upholstered furniture, decorations, and so on. According to the study conducted by , half of home fire deaths are from smoke inhalation and burns. However, smoke inhalation is deadlier as it is accounted to almost half of fire-related deaths. For instance, in 2004-2008 study of home fires and associated injuries and deaths, 40% of deaths were due to smoke inhalation. In terms of fire-related injuries smoke inhalation still dominates burns at 41%. Most of fire victims killed by smoke inhalation are located well aware from the fire or in a room other than the room of fire origin. The reason provided is the effect of smoke and gas from fire that are spreading beyond the initial room. Moreover, according to same report, there are around 310,000 to 670,000 people exposed to fire generated smoke and gases while 20,000 to 23,000 are injured and killed. Figure 1- Share of fire deaths by smoke inhalation or burns The causes of fire vary from country to country but the most common triggers are faulty electrical appliances and cooking equipment while flammable interior furnishings and decorative materials are considered main fire hazards in dwellings. In the UK for instance, 20% of fires and 50% of deaths in dwelling are caused by ignited upholstered furnishings and beddings . The deadly consequences of fire not only affect the victims but their family as well. According to , fire fatalities are mostly innocent victims thus unacceptable and painful to the remaining family member. Most fire fatalities were found away from room where the fire originates indicating that they were victims of big fires and killed by large flames rather than smoke. 2.3 Fire and Human Behaviour Reactions of people during fire emergencies varies depending on the person role, experience, education, personality, availability of means of escape, and so on. Similarly, human behaviour is also responsible for fire occurrences that often lead to deaths and injuries. In fact, the major difficulty facing community fire safety initiatives is communicating life safety awareness and practices to people with different behaviour in terms of fire safety . For instance, it is a common knowledge that fire is ignited by heat sources and thrived in combustible materials around us but despite this knowledge fires still occur either accidentally, deliberately, or carelessly some people. According to , the purpose of fire safety campaign is to promote a mindset that foster awareness of danger of fire, recognition of appropriate fire safety behaviour, and to motivate everybody to take action against fire. This is because some people actually possess contrasting belief and behaviour about fire. For instance, despite significant number of tragic fire incidents and reports about careless smoking, some people still ignore the danger of falling asleep while smoking. Another problem is careless cooking and using range or oven for room heating . In NFPA 921, human behaviour in fires is categorised into response and fire initiation. The reason for this is the fact that fire incidents often occur as a result of act or omission of one or more individuals. For instance, some people ignore operating procedures and equipment maintenance that often lead to malfunction and fire. Others are careless and store paper products or liquid accelerants near a source, ignore grease build-up in cooking areas, and carelessly discarding cigarettes or matches anywhere, ignore product labels, instructions and warnings and use them beyond their capability. Moreover, human fire initiation behaviour is not limited to accidental and carelessness as there are fires that were deliberately started by people with psychological or emotional problems, people under stress and anger, and anti-social behaviour . 2.4 The Concept of Fire Prevention Fire prevention is generally the desire to prevent hostile fires, reduce death and fire-relate injuries, and eradication of property losses to fire . However, approach to fire prevention varies depending on the political and economic climate. Similarly, fire prevention was carried out with different motives as some organisations are only interested in public welfare while others were driven by profit, reduced insurance payouts, and others . Fire prevention is one of the most important elements of fire safety and fire protection that covers minimisation of fire hazards. The first principle behind fire prevention is the fact that it is often easier to prevent a fire before it occurs than to detect and suppress it. Therefore, fire hazards around the house should be reduce such as faulty electrical wiring, malfunctioning heating and cooking equipment, and fuel sources that can support rapid growth and spread of fire . Fire prevention is not limited to reduction of fire hazards but adherence to and enforcement of building fire codes such as the use of fire-retardant materials in residential furnishing, low-flame spread materials for interior finish, and proper compartmentation. Moreover, fire prevention also include installation of fire detectors and warning devices in strategic locations around the building, fire sprinkler systems to suppress the growth of fire at earliest stage, and development of escape plan so that occupants can leave their home immediately . Fire prevention focuses on strategies that can help prevent the occurrence of fire. These include facility inspections, planning, safety and good housekeeping, storage and transportation of hazardous substances and materials, immediate and safe evacuation of occupants, education and training . 2.5 Fire Prevention Measures in the United Kingdom UK’s approach to fire prevention considers the three important aspects of fire safety such as performance, effectiveness, and reliability. The first one is generally about the proper operation of fire safety measures during a fire. This is because according to , these safety measures are affect by different factors such the origin the fire, growth rate of heat and smoke, and environmental factors such wind, weather condition, and others. Theoretically, a properly installed automatic fire alarm and smoke detectors and sprinklers are expected to activate whenever there is sufficient fire or smoke but in real-life situation, these devices can fail because high failure rate associated with its hardware components and factors not considered in their design. The second aspect on the other hand is generally concern on the effectiveness of fire prevention measures in reducing the number of fire occurrences and the ability of protective measures in reducing the damage when the fire actually occurs. In practice, the effectiveness of these measures is often determined by the likely reduction level that can be achieved in terms of human fatalities and property damage. The third aspect seems self-explanatory as fire safety measures are only effective if they are reliable or adequately operate in a fire . However, since real-life fire prevention activities include expenditures that must be incurred by the government, building owners, individuals and organisations, it should be justified further in terms of economy efficiency . For instance, if the proposed fire prevention includes modern equipment so that fire fighters can perform a timely response, then the cost involved should be weigh against the benefits which should be higher or exceed the cost. Fire prevention activities in most countries are often carried out by the fire department. In the UK, activities of the fire and rescue service include public education and inspection. The public education activities include visits to schools and community groups, posters, television advertising, fire prevention week, and so on while inspection is carried out regularly to identify fire hazards in the home and in the workplace . Fire prevention in the UK is legally enforced by several relevant legislations such as the 2005 Regulatory Reform (Fire Safety Order), Fire Precaution Acts, and others, and supported by different fire safety framework and guidance. In response to dwelling fires, UK government developed a “home” version of its fire safety guidance. The guidance provides practical tips and advices that household members can do to prevent or protect them from fire such as choosing and installing smoke alarms including instructions on how to make sure that it works and necessary safety precautions to prevent failure. More importantly, it contains information on how to prevent common fires and instructions on how to create an effective escape plan. These include safe cooking practices and electrical equipment maintenance, escape route planning, and correct behaviour during a fire . Since there in the best position to advice, the role of UK fire services is to spearhead the development of fire prevention and control. These include educating people on actions that should be take when a fire is discovered, the proper evacuation procedures, location and operation of fire-fighting equipment, and how and when to contact the fire and rescue service . 2.6 The Role of Fire-fighter Response Time in Preservation of Life and Property Fire fighter response time begins the moment they are on their way and end when they reach the fire scene . Therefore, this does not include the dispatch time or the time they received a call and getting information of the incident and turnout time which is the beginning point of response. In NFPA 1710, the standard response time for fighters is 4 minutes or less measured upon the arrival of the first fire engine . The reason or logic provided by NFPA is the fact that the most effective strategy to reduce loss of lives and property damage is to conduct an early aggressive and offensive attack on a growing fire . The 4 minutes response time standard is based on fire propagation curve as shown below. Figure 2 - Fire Propagation Curve According to , the above fire propagation curve corresponds to the percentage of property destruction and the approximate time where flashover occur in the room of origin. In other words, the most effect way to limit spread is to attack and extinguish the fire as close to the point of its origin which is from 1 to 8 minutes. However, as shown in the figure, an 8 minutes response seems too late as the percent of property of destruction is already half or 50. This suggests that 5 minutes or less response time is ideal in terms of property destruction and fire spread because damage from fire is minimal. Evidently, if the fire is suppressed at the earliest time, fire fighters also save a significant number lives including themselves. According to , the major objectives of fire and rescue department is to protect residents and minimise property loss, and reduce fears in the community thus both response time and fire prevention activities are important. However, response time is affected by a number of factors such traffic congestion, location of fire station, and false alarm that similarly consume resources and fire fighter time. In essence, these problems can be reduced by proper planning and fire prevention that teaches residents of the implications of mistakenly calling the service . In response to criticisms about increasing response time, the UK fire and rescue service leadership in 2008 blamed traffic congestion for the delay. This delay in response time according to the report contributes 13 additional fatalities every year. The recommendation is to reduce reliance on emergency response and concentrate on intensifying the service’s fire prevention activities. This is because UK authorities believed that while speed of response still matters and responsible for around 20% of cases where deaths after the emergency call is made, it is not the only solution to reduce deaths from fire. In fact, dwelling fire fatalities fell by 142 from 1996 to 2006 despite poor response time in the same period . However, as far as UK legislation is concern, the fire and rescue authorities regardless of road traffic problems should demonstrate effective fire fighting capabilities. For instance, they are required by the Fire and Rescue Service Act 2004 to equip and effectively respond to emergencies thus increasing response time is not an excuse . 2.7 Safer Community and the Legal Obligation of the Fire and Rescue Service The term “community safety” is a broad field involving various mainstream public policy fields such as education, social work, housing, planning, and so on. In the UK, community safety became a legal requirement for England and Wales through the Crime and Disorder Act 1998 which is mainly to reduce crime (not fire or any community safety concern) through community partnership . However, due to increasing fire fatalities and fire casualties occurring within domestic properties, fire-related concern in the community becomes a statutory obligation through the Fire and Rescue Service Act. Since then and with the advent of Fire Safety Order 2005, objectives of safer community initiatives include the legal obligation to ensure safety of the community from fire . Under the community safety agenda, the UK fire and rescue authorities continue to get involved in community, multi-agency approaches, application of Integrated Risk Management Plan or IRMP. IRMP is a document containing strategies to fire and prevent fires effectively and economically. The main aim of IRMP is to improve community safety and use of FRS resources by reducing the incident of fire, loss of life, severity of injuries, protect the environment, and provide the community with value for money . The concern over community safety dramatically change the fire and rescue service and in particular is now expected to focus more on fire prevention rather fire fighting. For instance, the UK’s fire prevention strategy is centred on three elements – enforcement of building regulations, maintaining a fire safe environment, and promotion of community fire safety. Moreover, since the primary concern is to prevent fires and reduced fire hazards, the fire and rescue service is no longer required to provide detailed schedule of safety requirements and issue fire certificate. Instead, they are now mandated to enforce compliance with regulations by requiring building owners to conduct a risk assessment, support and engage in social inclusion, neighbourhood renewal, and crime reduction. More importantly, the fire and rescue service now have the responsibility to produce and publish local standards of service describing how they would create a safer community . References: Bigelow, E. L. (2009). Fire Safety Now! A Guide to Fire Safety Principles and Practices, FireSafetyNow.USA Bradley, A. (2012). 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Computer Safety, Reliability, and Security: 29th International Conference, SAFECOMP 2010, Vienna, Austria, September 14-17, 2010, Proceedings, Springer Smoke, C. H. (2005). Company Officer, Delmar Cengage Learning  Read More