Fire Behavior in Compartment with Failure of Passive and Active Systems - Term Paper Example

Running head: FIRE BEHAVIOR Student name: Student number: Course title: Lecturer: Date: Fire behavior in compartment with failure of passive and active systems. Introduction. In many buildings, structures and vessel it is common belief that by applying the prescriptive codes which involves installing both passive and active systems the damage created by fires is highly reduced. While this is true, it is however important to do regular maintenance on passive and active systems in building. It is important to apply law enforcement to mandate the owners of these structures to do maintenance so as to achieve a high level of performance in the event of a fire. Inspections of the buildings are important to ascertain that the building is compliant to the fire code. Regular training is often issued at different levels in order to ensure that the occupants and operators of the building get the technical-know-how of evacuation in accordance to the structure survival ability (Cater 91). Basic Principles of Fire Behavior The first principle of the behavior of fire is the Fire Triangle or Tetrahedron. This entails heat or the source of heat, oxygen, fuel and a chain reaction. If an instance occurs whereby one of these four items is removed then the fire cannot survive. This is the basis on which all fires are brought about and extinguished at the same time. These are the ingredients of forming a fire (Wagner 76). The second principle of the behavior of fires in buildings is the method of transferring the heat. We have the direct flame contact whereby, heat is transferred by virtue of contact between the flame and the object and in this case, the building or the objects in it. Secondly, there is convection, convection is a process whereby heat is transferred in fluids (liquids and gasses) whereby one portion of a fluid mixes with another portion of the fluid. In gasses, this is brought about by difference in densities between the cooler parts of the gasses and the warmer parts of the gas. Thirdly, there is conduction whereby heat is transferred from one body to another by the virtue of contact between the bodies or by the means of a medium, in this way heat is transferred by vibrations of its molecules. Fourthly, heat can be transferred by the means of radiation; this is the transfer of heat through heat waves whereby heat can be transferred due to temperature difference between warmer bodies to a cooler body. Radiation has been known to be the main cause of explosion related fires (Wein and MacLean 62). The third principle of fire behavior is the stages fire growth. Fires are usually started off by an ignition, different conditions have different ignition temperatures and therefore it is important to note that the ignition temperature must be reached in order to have a fire. Ignition temperature is the lowest temperature at which a fire can be caused on any combustible item when the temperatures are low. After this point, the fire or the combustible item will reach the flame Point. The flame point refers to the point at which the fire will keep on burning after the point of ignition for a particular period, for example five seconds. Then there is growth stage whereby as more oxygen is consumed the fire gets hot with time. Fully involved refers to the peak of the fire which follows after the growth of the fire stage, this is normally reached after the flash point which refers to the lowest temperature at which a material can emit vapor combustible in air mixture higher than Flame point of same material. This in effect causes a flash Over, which is the point where unburned combustible materials reaches their fire point and consequently ignite in an enclosed area or space, causing a roll over. This stage or rather process is followed by the decay stage whereby the fire starts to die out because there is insufficient supply of oxygen. When a fire has insufficient supply of oxygen the resulting effect is a back draft. The fourth principle of fire behavior is the thermal layering. Thermal layering is a conditions that arises when heat rises. Normally Oxygen is pushed to the ground and it is cooler as well.In thermal Layering, there are three different thermal layers. The top level layer is usually the ceiling consists of extremely heated or superheated gases. The super heated gases at this layer collect and this explains why it is the hottest layer, the middle layer consists of moderately heated layer lower, here, the temperature is less than the extremely heated layer. The last layer is the Lower heated level where the temperatures are cooler than all the other layers. The fifth principle is the Flash Over. The flash over is the point whereby unburned combustible materials reaches their fire point and consequently ignites in a closed area or space, causing a roll over (Wagner 72). Constructing a building that is compliant to the version requirement of the local building code * Maintenance of the building and conducting yourself in. This is based on the occupants and operators of the building being aware of the regulations provided in the fire code. Examples of these regulations presented in a fire the fire code include the following precautionary measures; Regulating the building occupancy at any given time at any part of the building and defining proper fire exits in a building such that in the case of a power failure caused by a fire, the fire exits have visible pointers (Riddell 872). *positioning and maintaining firefighting equipment in places that are easily identifiable. Firefighting equipment include axes, fire extinguishers that are properly labeled, alarm systems and their triggers such as the smash glass (Ratcliffe, Stubbs and Keeping 72). * Prohibiting combustible items or materials such as petrol in particular areas of the building. * inspection of the buildings for violation of regulations provided on the fire code, giving orders which the building should comply with, prosecuting the owners of the buildings that are not in compliance with the fire code or alternatively closing buildings that are not in compliance until the requirements are met (Perera, Euler and Thompson 143). *installation and maintenance of fire alarm system to alert the occupants of the building of fire * training the occupants and operators of a building in case of a fire in order to avoid mistakes, for example defining a fire assembly point. * Conduct fire drills. PASSIVE SYSTEMS These systems are employed in a building to contain a fire in its area of origin in order to prevent the spread of fire and smoke for a given duration of time. The main aim of passive system is normally to fire test the material at for example 140 degrees Celsius or Ca 550 degrees Celsius, which is considered as the critical temperature of steel above which steel loses its strength leading it to fail. This has formed the basis for designing and constructing walls in buildings. Passive systems employed in a building include the following: Compartmentalization of a building - this involves dividing the building into fire compartments that are made of fire resistance rated walls and floors. Compartmentalization has been known to prevent the spread and slow the rate at which fire spreads from the compartment (room) of origin to other compartments and the entire building. This therefore ensures sufficient time for emergency evacuation. The use of fire resistant glass that is made by embedding wire mesh with glass fire doors Fire resistance rated floors. Fire dampers Fire stops Cable coating which involves applying fire retardants on cables to reduce fire spread and smoke development. Fire resistance rated walls (Molchanov 82). Closures Use of grease ducts which are made from commercial cooking equipments Spray proofing- this involves the use of endothermic paints on structural steel. Fire proofing. ACTIVE FIRE SYSTEMS. These systems employed to a building require some level of response in order to work. There are various examples of active fire systems that include: The sprinkler system-these are usually positioned at the level of the ceiling and are connected from a source of water that is considered. It works by heat mechanism whereby heat triggers a glass component on the water head to break and thus the sprinkler releases water (Greay Britain. Office of the Deputy Prime Minister 72). It is important to note that the sprinkler at that particular point of fire will be triggered and not the whole sprinkler system of the building Fire suppression, this involves manual or automatic means used to control a fire. Manual control involves the use of fire extinguishers or standpipe systems. Automatic means include the use of sprinkler systems, use of fire fighting foam (Compartment Fire Behaviour Training CFBT Steering Group 411). Fire detection. Fire is normally located using flames, smoke or heat or a combination of two or all of these. Smoke, fire or heat activates the detection system, which carries out any activity such as opening fire doors, opening the servo-activated vents in the stairways (Chow 96). Fire behavior in high-rise buildings with failure of both passive and active systems. High-rise buildings depend on three fire defense systems that include the sprinkler systems, active fire fighting systems and passive protection. High-rise buildings are normally designed to with stand a fire that can consume all the combustible material in the building. Factors that often result in failure are inclusive of fire behaviors such as fire growth, fire intensity, fire resistance issues and the presence of a fuel (Barrows 54). When the fire grows to a large magnitude, it causes the intensity of the fire to increase or rather the heat to increase. High intensities of the building fire and a high demand for water could render the sprinkler system ineffective or non-operational. Fireproofing is a passive fire protection system for structural members for a given duration of time, however, with the growth of the fire intensity, the structural members are weakened considerably thus the failure of both active and passive fire protection systems Case study one The world trade centre Two commercial planes that were laden with jet fuel struck the world trade centre. After this impact, the building burnt and later on collapsed. The collapse is said to be of the first kind as it was the first fully structured steel building to collapse in history. A scrutiny to the building indicates that the passive systems were in good working conditions, therefore the active systems that were meant to quell the fire failed due to a number of reasons. It has been established that the fire burnt the building and when it reached uncontrollable levels the building consequently collapsed. The sprinkler system in the building failed or rather it was not enough to stop the fire, this therefore encouraged the fire to grow. This coupled with the fact that the fire fighters were instructed to stand down made the intensity of the fire to grow. Sprayed fire resistance material was used as an agent on the steel as a passive fire protection system however due to the thermal expansion, the material failed and therefore the steel structure. Buildings are normally designed to ensure protection from fire hazards and safety from fire perils. Two methods that include passive and active systems has been employed for fire protection and safety in buildings. Case study 2 Madrid/Windsor Towers. Madrid got burnt in 2005 and it had thirty two floors. The passive systems in this building failed and therefore it exposed the building to fire hazards. For example, the Madrid tower was in short of adequate compartmentalization. This infect gave the fire a gateway to spread quickly to other floors and thus spreading to the entire building. The building also suffered insufficient fire proof coating thus it exposed structural steel to fire. However, when the fire spreads rapidly the active fire systems become inadequate for example in the Madrid tower the sprinkler system was not there as the building was constructed at a time when the fire extinguishing technology was not advanced. The building thus succumbed to failure and thus its collapse. CASE STUDY 3 One meridian plaza in Philadelphia. The fire at the one meridian in Philadelphia is a good example of a fire that was triggered and the spread of fire was catalyzed by the presence of a fuel. It was established the building's genitors left behind sags that were laden with oil. Due to limited fire proofing and compartmentalization the fire spread to other floors from the twenty-second floor both the lower and upper floors. Therefore, the passive fire protection systems were inefficient. However, the sprinkler systems were not fully installed as a tenant only installed them on the 30th floor. The sprinkler system installation was not a requirement by the building code in the city. The fires in the building burnt ferociously causing extremely intense fires. The window glasses and frames therefore melted. The concrete slabs and steel beams deflected and therefore the building were exposed. When the fire reached the 30th floor, the sprinkler system installed by a tenant was triggered and the fire was extinguished. Fire behavior in buildings with failure of both active and passive fire systems. When a fire breaks the safety of the building's property and occupants is normally ensured when the active and passive systems work together in unison to bring down the fire. Active fire protection systems are meant to control and suppress the growth of a fire. It concerns itself with detecting and triggering a mechanical means of extinguishing a fire or triggering sensors connected to fire fighting equipments such as sprinkles (Cater 33). Passive fire protection systems are mainly part of the design and construction of a building such as smoke dampers stairways for evacuation. Some fires have caused failure of the passive and active systems this is often because of fire growth, an explosion and growth in the intensity of the heat (Brebbia, Neophytou and Ioannou 7). However, when the passive and active fire protection systems are not periodically inspected then they do not function properly in the event of a fire. Active fire systems can fail if not inspected regularly or might be insufficient in the case where the intensity of the fire is great. This is often because of change of behavior of the fire for example when the fire grows in size and intensity. Passive fire systems are can also be bound to failure in the case where fire intensity reaches the critical temperature of its structural members (Bengston 90). This often because the active systems could not contain the fire. This causes the structural members to fail and thus the passive systems fail if and only if the active systems fail. Case study 4 Interstate bank building fire. The Interstate Bank fire building was an ideal fire. The building was furnished with both active and passive fire systems; however, the sprinkler system was in the process of being installed. The smoke detector systems went off on the 12th floor of the building. Considering that the fire sprinkler system was being put in place the water flow was still deactivated and could not be activated in the event of a fire. The fire extinguisher companies were called upon, however the fire was too big and the fire fighters were called off. The stairwells were in good working condition and therefore some people were rescued. The glasses that were falling over made the fire extinguishing operations by fire extinguishers impossible. The fire therefore made the twelfth floor to collapse as the fire proofing material on the steel structure succumbed to the intense heat. However it is a fact that steel cannot melt as a result of heat from a fire, it is undisclosed as to what made the 12th floor to collapse. Case study 5 Nakumatt centre building fire. Nakumatt is a building in Nairobi, Kenya. It was a three-storey building. The fire was started and the gas cylinders in the shopping mall exploded causing the fire to grow in size and intensity. The fire sprinkler system was inefficient as the water was not enough to put out the large intensity of the fire. Nakumatt building was a shopping mall, therefore there was little if any compartmentalization in the building. There was no fire proofing material on the building and therefore the fire grew. The building lacked fire resistance glass and fire stops and therefore the passive fire systems failed in general. The fire fighters arrived late and put the fire in control, however death was reported and immense amount of property was destroyed. Conclusion. Active fire protection systems are internationally used for protection of the buildings by extinguishing the fires and controlling the fire. Active protection includes sprinklers, foam pourers, water monitors, and use of inert gases for flooding spaces. Passive fire protection involves coating a fire resistant material on the structural members of a building to contain the fire in the event of a fire. Factors that have resulted in the failure of both active and passive fire protection include: fire growth, fire intensity, fire resistance issues and presence of a fuel (Albini 76). Failures of both active and passive systems can have catastrophic results in the following ways: A fire can grow because of the presence of a fuel or an explosive such as petrol or oil or if the active systems such as sprinklers fail to contain the fire. This normally cause the intensity of the fire to increase. This often causes injury, loss of life and destruction of property by burning. Fireproofing is a passive protection system on structural member of a building for a particular duration of time. However, when the fires advances to uncontrollable levels the structural members of the building fail. For example, steel loses its loading capacity when exposed to an ASTM E-IA standard fire that is used as a standard in building fire. When this standard is exceeded and steel fails, the building collapses. This is catastrophic as it could lead to loss of lives of the occupants of a building and fire fighters and because it destroys the building and the property in it. When a building collapses it produces dust which can suffocate people in the surroundings of the building thus the death of such people. The Debri also destroys property in the surrounding area. When the smoke dampers are ineffective or non-operational an immense amount of smoke is produced which can cause suffocation of the occupants of the building. The smoke not only causes choking and suffocation but also pollutes the air. Works Cited Albini, Frank A. Estimating wildfire behavior and effects. Utah: Ogden Publishers, 2000. Barrows, J S. Fire behaviour in northern Rocky Mountain forests. Chicago: Range Experts, 2000. Bengston, Vern L. Fire behaviour and management. New York: Sage, 2005. Brebbia, C, et al. Sustainable development and planning IV. New York: WIT Press, 2009. Cater, J. Fire management systems. New York: ACP Press, 2008. Cheney, Phil and Andrew Sullivan. Grassfires: Fuel, weather and fire behaviour. New York: Csiro Publishing, 2009. Chow, W. "Fire safety in green or sustainable buildings: Application of the fire engineering approach in Hong Kong." Architectural Science Review 46.3 (2003): 297-303. Compartment Fire Behaviour Training CFBT Steering Group. Guidance and compliance framework for compartment fire behavior training: Fire service manual. London: Stationery Office, 2000. Greay Britain. Office of the Deputy Prime Minister. Sustainable development im rural areas. London: The Stationery Office, 2004. Molchanov, A. "The speed of advance of forest fires and its dependence on meteorological conditions." Lesnoe Khozyaystvo (1940): 6. Perera, Ajith, Dave Euler and Ian Thompson. Ecology of a managed terrestrial landscape: Patterns and processes of forest landscape in Ontario. New York: UBC Press, 2001. Ratcliffe, John, Michael Stubbs and Miles Keeping. Urban planning and real estate development. London: Taylor & Francis, 2009. Riddell, Robert. Sustainable urban planning: Tipping the balance. New York: Wiley-Blackdwell, 2004. Wagner, Van. Conditions for the start and spread of crown fire. New York: Cengage Learning, 2001. Wein, Ross Wallace and David MacLean. The roe of fire in northern circumpolar ecosystems. California: Wiley, 2003. Read More