The Role of Fire Engineering - Assignment Example

1Title: Fire engineering Dated: March 15, 2009 T1. Review the main features of radiation and analyze the radiating gases produced in combustion. Explain the role of radiation in fire spread between neighboring buildings and discuss the requirements for space separation (6 marks). Answer: Radiation is the process through which energy travels through space from one place to another with a net result as shifting of energy. Radiation process is associated with the combustion mechanism which in turn can be defined as the sequence of heat releasing process in the form of chemical reactions with the utilization of fuel as the burning material and an agent which facilitate the process(Fernandes and Heitor,1996.p.4) (1). The facilitating agent is the oxidizing agent that is oxygen in the burning process. During the combustion process two major agents take part as major inputs that are fuel and oxidizing agent and through the process outputs are released along with the energy in the shape of heat. This heat transfers fro the site of production to the surroundings as through conduction, conviction and radiation. The nature of the radiating gases as produced during the combustion process depends upon the type of fuel and the level of the combustion (Glenn, 2007) (2). For example, carbon dioxide is produced with the utilization of the hydrocarbons and nitrogenous gases are produced from the nitrogenous compounds as the radiating gases. Fire is spread by three general methods as convection, conduction and radiation between neighboring buildings, however, radiation is the major mechanism in this regard. The spread of the fire into the neighboring buildings through radiation could be restricted with the use of fire separation techniques and the instruments. The transfer of heat through radiation needs to be lowered with the help of fire doors as in the form of closed doors by holding back smoke and the fire. The fire separation techniques with the help of fire resistant materials and the closure of the holes in the neighboring buildings, the blockade of the flow of heat through radiation among the buildings and furthermore within the building under fire will ultimately result through the usage space separation among the buildings. The start of the fire in the buildings and its spread through radiation are reduced with the help of the space separation as the space will serve as a barrier in the restriction of the fire spread among the neighboring buildings (Jaffin, Bob, 2008). (32). T2. Critically analyze the effect of enclosure ventilation on combustion and the composition of smoke (6 marks). Answer: The combustion is the sequence of the chemical reactions in which heat is released from the system into the surrounding with the utilization of the fuel as the material for the burning process and the agent for example oxygen for the completion of the process. The places where the combustion processes take place are the systems and the neighboring structures are the surroundings of the systems. The ventilation systems have the capacity to affect the combustion process through their specific position and working status in the buildings under fire. Working ventilation systems help in the spread of the fire through the release of the smoke and heat from the building under fire into the neighboring buildings. The ventilation systems are supplied with the fire detectors and these detectors convey the signals for the closure of the ventilation systems. The compartments and the sub-compartments in the buildings with the help of fire dampers assist the fire control system as in accordance with the fire safety standards. A fire in a building can produce smoke that is black and thick, obscures vision, generates great difficulty in breathing, and similarly can block the escape routes during the fire incidents in the buildings. Smoke, is a grave threat to life which should not be overlooked. The composition of the smoke as is produced during the fire incidents in the buildings has the influence on the combustion process as thick smokes or thin smokes has the influence on the combustion process through heating rate ,duration of the fire along with its intensity for the spread of the fire. The administrators formulate their fire management strategies with the examination of the smoke of the fire (Sally, 2000) (4)3. The quality of combustion can be improved with the help of the analysis of the nature of the smoke as is produced in the process. Majority of people who die during the fires are overcome by the gases and the smoke as are produced during the combustion process. Evaluation of the risk to people in the fire premises requires a basic analysis of the way fires develop and how smoke can spread within the buildings including the neighboring buildings. T3. Analyze the effect of varying compartment/building geometry and fire location on the production of smoke. Compare various plume types including: axisymmetric plumes, adhered plumes, spill plumes etc (6 marks). Answer: The building geometry, compartments in the building and fire location has impact on the production of smoke during the fire incidents in the buildings. Buildings with high roofs and rectangular in shapes with proper ventilating systems have arrangements for the production and spread of smoke in the buildings. The location of the fire in the main centers of the buildings has comparatively reduced chances for the spread of fire within and outside the buildings. On the other hand, the location of the fire in the close proximity of the walls along with their materials produces smoke in the vertical as well as horizontal directions. Precautionary measures as adopted by the administrator help in the control of the fire incidents and the transfer of heat through radiation in the buildings. The administrators apply insulators, spaces and other fire preventives for blocking the movement of fire in the buildings. A cavity in the buildings is a concealed space which is enclosed by elements of a building within the building elements. The unseen spread of smoke within these spaces could pose a serious threat to the occupants, mainly those with high degree of dependency on the buildings. The structure and geometry of the building has influence on the fire spread on the internal linings and external walls of the buildings (Paul, 2004) (5)4. Plumes in different models like axisymmetric plumes, adhered plumes, spill plumes, etc; have influence on the production and release of smoke in the buildings through the viscosity. Axisymmetric plumes direct the smoke in the vertical direction through its unique geometry and arrangements. In the adhered plumes, the smoke is adhered to the walls of the structure during flow of the smoke through the apparatus. A spill plume model is projected to forecast the properties of the plume development in the atrium zone in a retail shop fire. These plumes in the combined form lead to an improved zone model for its proper functioning as an improved structure in the buildings. T4. What is the function of smoke control? When and where is it required? Critically analyze methods of smoke control (6 marks). Answer: Smoke control is an arrangement that covers physical features of the smoke, equipment as are involved in the process and the methods which are used for the movement of smoke in the fire cases of the buildings. Physical features are passive characteristics in the smoke control process and are based on the geometry, design and construction of the building. These characters determine the direction of the smoke and therefore, the whole fire management process (Glasspool, 2006) (6)5. Equipment, which are applied are the fans, smoke detectors and operable windows and supplement the smoke controlling systems in the buildings. Methods and the design schemes such as smoke venting, smoke control and compartmentation work together during the whole process for effective smoke control mechanism. Physical features are applied to control smoke movement by restricting the smoke within the smoke source area. Smoke venting are applied as non-ducted and stand alone equipment in the buildings. These are designed to control smoke movement through releasing the smoke with its own pressure to the outside. The other equipment like fans, dampers, smoke detectors and duct work is used to control smoke movement in an actively and mechanically developed pressure differentials. Smoke control systems usually based on physical features for their proper working as the process is closely related with the fire management. Smoke controlling systems help in the implementation of the fire management systems for the safety and security of the buildings as well as the human beings as are associated with the buildings. Smoke control mechanism is a tool for the implementation of fire management strategy for the achievement of its targets that is to control the fire within a minimum reaction time, minimum losses both in terms of property and human life. A proper smoke controlling system is a guarantee for the achievement of the desired objectives that are associated with the fire management strategies. There are two basic types of smoke controlling methods as static or dynamic depending on the working and non-working of the allied structures during the smoke control methods. During a static smoke control method, all the fans in the building stop working during the control mechanism which results in simple compartmentational control of smoke of movement during the implementation period of the method. On the other hand, during a dynamic smoke control system, all are the selected fans continue to work in their normal working procedures for the creation of a pressurized space for the movement of the smoke during the process. T5. Critically analyze the use of standard fire curves for determining fire resistance. How and why does the approach vary for onshore and offshore applications? (6 marks). Answer: The standard fire curves are the simplest and easy procedures to represent a fire with the help of predefining some of the arbitrary time and temperature relationships. These standard fire curves are independent on ventilations and boundary conditions for the fire incidents. These curves were developed for the fire resistance furnace tests of the building material and other elements for their verification and their classifications. These curves are used for the representation of the fire incidents along with their intensities (Klote &Milke, 1992) (7)6. These curves are helpful for designing smoke control methods and fire management strategies for their effective utilization during the fire incidents in the buildings. The application of the standard fire curves vary for the onshore and offshore applications of these curves. In the onshore applications, these curves produce uniform results with the help of these standard curves. On the other hand, the application fire incident curves for the offshore applications have the ability to produce different results during their application. The standard fire curves do not represent real natural life as these curves are based on the two major variables as temperature and time. The difference in the heating rates, fire intensity during the fire incident and the duration between the standard and real fires can result in the production of different structural behavior. For example, a short duration with high temperature can result in the form of thermal shocks; on the other hand a long duration low temperature fire can result in a higher average temperature within the concrete members resulting in a greater reduction in the concrete strength of the building. References: 1. E. C. Fernandes and M. V. Heitor (1996). “Unsteady flames and the Rayleigh criterion” in F. Culick, M. V. Heitor, and J. H. Whitelaw, ed.s, Unsteady Combustion (Dordrecht, the Netherlands: Kluwer Academic Publishers, 1996), page 4. 2. Elert, Glenn (2007). "Chemical Potential Energy". The Physics Hypertextbook. http://hypertextbook.com/physics/matter/energy-chemical/. Retrieved 2007-09-11. 3. Jaffin, Bob (2008). "Emergency Management Training: How to Find the Right Program". Emergency Management Magazine. 4. Buchanan, Sally (2000). "Emergency preparedness." from Paul Banks and Roberta Pilette. Preservation Issues and Planning. Chicago: American Library Association, 159-165. ISBN 978-0-8389-0776-4 5. Rincon, Paul (2004). "Bones hint at first use of fire". BBC News. http://news.bbc.co.uk/1/hi/sci/tech/3557077.stm. Retrieved 2007-09-11. 6. Scott AC, Glasspool IJ (2006). The diversification of Paleozoic fire systems and fluctuations in atmospheric oxygen concentration. Proc Natl Acad Sci USA. 103(29):10861–5. doi:10.1073/pnas.0604090103. PMID 16832054 7. Klote, J.H., J.A. Milke. 1992. Design of Smoke Management Systems. Atlanta: ASHRAE. Links of the references: 1. (http://books.google.com/books?id=Je_hG6UfnogC&printsec=copyright&dq=rayleigh+thermoacoustic+&ie=ISO-8859-1&source=gbs_toc_s&cad=1#PPA4,M1) 2. http://hypertextbook.com/physics/matter/energy-chemical/http://physics.info/energy-chemical/ 3. www.io.com/~fuzzface/cgi-bin/nph-tokyo.cgi/000110A/687474702s656r2r77696o6970656469612r6s... 4. www.docstoc.com/docs/6400261/Emergency_management 5. http://news.bbc.co.uk/1/hi/sci/tech/3557077.stm. Retrieved 2007-09-11. 6. en.wikipedia.org/wiki/Fossil_record_of_fire 7. www.bfrl.nist.gov/IAQanalysis/applications/ref.htm Read More