Fire Hazards and Means of Escape from Fire - Assignment Example

All are answered by I find it difficult to answer Question 24. Can you send notes or something or maybe you can give me a little more time for this. Thanks 1. Give a definition of combustion Combustion is commonly known a burning up a substance and as it transforming wood to smoke and ashes Combustion is the consequence of chemical union of the oxygen of the air with the combustible body or some of its elements. The heat which comes with the chemical action give luminous the gases or vapours created that result into flame (Robbins 1986, p.66). 2. Fire safety in buildings is concerned with achieving two fundamental objectives, name them. Life safety is one of the most important objectives in the design and construction of any building. Fire safety often regard life safety by providing systems for early warning of a fire, extinguishment of a fire, and proper egress for prompt exiting from the building. Another central concern is property and environmental protection as maintaining the building and its content from damage is generally factor in terms of fire protection (Cote p.139). 3. What are the 5 functional requirements of Approved Document B? Part B of the Building Regulations requires buildings and other dwelling houses the following (taken from Furness & Muckett (2007, p.174). a. Means of warning and escape The building should be designed and constructed with suitable provisions for the early warning of fire and adequate means of escape. b. Internal fire spread (linings) Internal linings should sufficiently endure the spread of flame over their surfaces and should have sensible a rate of heat release. c. Internal fire spread (structure) The building should be designed to resist fire and maintains its stability at a reasonable period. d. External fire spread The external walls of the building should be able to resist the spread of fire over the walls and from one building to another. e. Access and facilities for the fire service. The building should be designed and constructed so as to provide reasonable facilities to assist fire fighter in the protection of life. 4. Give a definition for the term “Means of Escape from Fire” This means a special route provided for use in the event of fire such as escape routes, fire exits, and fire doors. This also means of ensuring that the means of escape is safe and can be use at all time. This can fire exit signs, self-closing devices on fire doors and emergency lighting. 5. What information do you need to know when designing means of escape? The following information is generally required when designing means of escape. According to Billington et al. (p.73), the designer must know the: a. Use of the building and the activities of the occupants. b. Nature of the building structure. c. Processes undertaken and or the materials stored in the building d. Potential fire sources and potential fire spread throughout the building. e. Standard of fire safety management to be installed. 6. Why is it important to perform fire test? A better understanding of the various fire test procedures and the significance of the results of such tests will be very helpful in promoting the development of new fire-resistant materials and systems and will lead to a better appreciation of the accepted fire resistances of existing materials (ASTM 1992, p.1). The primary importance of fire test is generally to be able to relate the performance of the product such as ignitability or the tendency to propagate flame, to practice (Totten & Reichel 1996, p.81). 7. Why is it important to carry out more than one experiment to test the same parameter? It is important to carry out more than one experiment using the same parameter because the test should reflect the hazard being test as closely as possible. Thus, if more than one hazard is present then different test may be required for each hazard. 8. Explain the term “trench effect”. Similar to the Kings Cross fire in 1987, the ‘trench effect’ occurs when the fire suddenly went from a seemingly safe stable state confined to a small physical area to another state in which flames filled the escalator shaft and roared out of the top of the inclined shaft. The geometry of the escalator or ‘trench’ and the incline of the shat were critical to the occurrence of this violent flashover (Mahoney 1992, p.61). 9. Define the terms “upper and lower flammability limits”. A combustible gas-air mixture can be burned over a wide range of concentrations, either when subjected to elevate temperatures or exposed to a catalytic surface at ordinary temperatures. However, homogenous combustion gas-air mixtures are flammable, that is, they can propagate flame freely within a limited range of compositions. For instance, a trace amounts of methane in air can be readily oxidized on a heated surface, but a flame will propagate from an ignition source at ambient temperatures and pressures only of the surrounding mixture contains at least 5 percent but less that 15 percent methane by volume. The more dilute mixture is known as the lower flammability limit or the combustible-lean limit mixture while the more concentrated mixture is known as the upper flammability limit or combustible rich limit mixture (Haessler 1989, p.22) 10. There are five main factors which will affect the development of fire growth within a compartment. They can be divided into two categories: those that are concerned with the compartment itself and those which are concerned with the fuel. Please name four of these factors. The factors that influence the development of fire in an enclosure are (Karlsson & Quintiere (2000, p.21) : the size of and location of the ignition source the type, amount, position, spacing, orientation, and surface area of the fuel packages the geometry of the enclosure the material properties of the enclosure boundaries 11. Discuss and explain the stages of fire development. There are three stages of fire development- beginning or incipient stage, free-burning stage, and smouldering stage. During the incipient stage, fire is localized to the point of origin. At this point, there is a lot of oxygen present for the fire to burn and little smoke being created. Hot gases are increasing in a thermal column away from the fire. Convection pushes these gases to the higher parts of the room or inside the structure. If a solid fuel be present above the flames, convection and direct flame contact extend the flames up and out from the source in a distinctive “V” pattern of char. Meanwhile, during the free-burning phase, the fire grows in strength and spreads through the fuel in the room. Other fuels in the room are heated until they attain their ignition temperatures. Smoke and fire gases persist to increase in the room, until they get to the ceiling and begin to bank down. When these gases attain their ignition temperatures, flashover take place in the room. After flashover, the fuels in the room will keep on burning as long as oxygen and fuel are there. After a period of time, the fuel will be exhausted and the open flame burning will drop- this is known as the smouldering stage (Burke 2007, p.253). 12. Combustible and flammable fuels involved in fires have been broken down into five categories, identify them. The fire categories are (Blaus 2005, p.1) Class A fires are those involving organic solids such as papers or wood Class B fires are those involving flammable liquids Class C fires are those involving flammable gases Class D fires are those involving metals Class F fires are those involving cooking oils 13. Name four parameters you can determine using the cone calorimeter. Heat of release is one of the most important parameters than can be determined using the cone calorimeter (Rapra Technology 1996, p.3) and the others are (Crompton 2006, p.507). Rate of heat release per unit area Mass loss rates Time to ignition Effective heat of combustion 14. Explain what is meant by the “ignitability” of material. Ignitability is the point with which a material can ignite when subjected to flame (Stollard & Abrahams 1999, p.29). In other words, ignitability is a materials’ susceptibility to spontaneously burn or combust. The common used indicators for determining the ignitability of material are flash point or auto-ignition temperature (Saxena 1993, p.146). 15. Explain what is meant by “positive pressure ventilation”. Positive pressure ventilation is the application of positive pressure by using mechanical means after the fire has been knocked down. It is a method to pressurize structures during overhaul and in stairwells of high-rise buildings (Garcia et al. 2006, p.82). 16. Explain the difference between heat and temperature. Heat is commonly known as energy in travel. It is some sort of energy transferred from hot things to cold things when they come into contact (Blundell 2006, p.13) while temperature is the measure of how hot or cold these things are (Olien 2004, p.4). 17. Why it is important to investigate the cause of fires? The basic objectives of any fire investigation is to establish and document the origin and cause of the fire and learn what human actions or failures contributed to ignition and fire development (Kolko 2002, p.88). A good fire investigation can provide information that can be used for making proposal and developing programs that help prevent accidental or incendiary fires (Davletshina 1998, p.8) 18. Explain the difference between a diffusion flame and a premixed flame. In the premixed flame the air for combustion is mixed with the fuel gas or liquid leaving the orifice, while in a diffusion flame gas or liquid leaving the orifice is pure fuel and the air for combustion has to diffuse to it from the surrounding atmosphere. In a Bunsen burner, a premixed flame can be obtained by opening the primary air inlet and a diffusion flame by closing it. The rate of burning in premixed flames is limited by reaction kinetics while in principle, with a diffusion flame the rate of limiting mechanism is diffusion (Mannan & Lees 2005, p.16). 19. Explain what the flashpoint of a fuel is. One of the most important properties of the fuel is the flashpoint because it is that liquid temperature which results in sufficient fuel vapour pressure at the liquid/air interface to produce a flammable mixture of fuel vapour and air over the surfaces (National Research Council 1997, p.128). In other words, the flash point of a fuel is the temperature to which the fuel must be heated to produce an ignitable vapour-air mixture above the liquid fuel when exposed to an open flame. 20. Why are vapours important to the burning process? In gasoline for instance, when the temperature passes its flashpoint, it gives off sufficient flammable vapours to support combustion. When these vapours reach an ignition source, the vapours will ignite in a ball of fire. The burning process for both ordinary combustible solids and liquids requires the material to be vaporized because it is not the actual solid that is burning, but the vapours being emitted from it. (Cheremisinoff 2001, p.120) 21. Explain the limiting oxygen index test. When judging the flammability of a solid, an oxygen index test is commonly use. The test involving igniting a vertical pencil-sized sample at the top, in an oxygen-nitrogen mixture. The proportion of oxygen in the mixture is reduced until the flame goes out. When extinction occurs, the percentage of oxygen by volume is called the limiting oxygen index (Friedman 2008, p.144). 22. What are the limitations of the limiting oxygen index test? The limitations of the limiting oxygen index test is the fact that the results do not correlate consistently with important measures of flammability such ignition delay time versus radiative flux, flame-spread rate, and heat-release rate versus radiative flux (Friedman 2008, p.144). For instance, according to Brydson (1999, p.105), the limiting oxygen index does not characterise the burning behaviour of the polymer. 23. Explain the terms ‘piloted-ignition’ and ‘auto-ignition’ A piloted ignition is caused by a localized heat source such as an open flame or a spark while an auto ignition or self-ignition occurs when a sufficiently high temperature of the pyrolyzed gas and air mixture is reached. Moreover, piloted ignition temperatures are much lower than auto-ignition temperatures (Fitzgerald 2004, p.96). 24. Presented below are 10 heat release rates for a piece of laminated wood at 25.00kW/m2 Calculate the range, the mean, the standard deviation and then the uncertainty in the mean and the uncertainty in the standard deviation. Test 1 2 3 4 5 6 7 8 9 10 Heat Release Rate @ 24.00kW/m2 44.8 42.15 42.97 43.60 43.88 44.80 42.79 45.10 41.62 43.74 25. In the table below there is a set of results obtained from the ‘Bang Box’ experiment. Plot a graph which best show your results and state what the results show. Based on the graph plotted, the height attained by fuel acetone from test 1 to 6 generally increased and climber to its peak at 150. However, data on test 7 that when the drops exceeds 16, the height began to drop considerably at 110 and then to 90. The results conclude that the flammable rate of acetone fuel depends on the number of drops or the volume of acetone fuel. Fuel Acetone Test 1 Test 2 Test 3 Test 4 Test 5 Test 6 Test 7 Test 8 Number of Drops 2 6 10 12 14 16 18 20 Height Attained by lid (cm) 0 20 40 80 120 150 110 90 Bibliography: ASTM. 1962. Symposium on fire test methods, ASTM International, US Billington M. J., Ferguson A., Copping A. 2002. Means of escape from fire, Willey-Blackwell, UK Blaus J. 2005. Electrical installations: NVQ and technical certificate. Heinemann, UK Blundell K. M. 2006. Concepts in thermal physics. Oxford University Press, UK Brydson J. A., 1999, Plastics Materials, Butterworth-Heinemann, UK Burke R. 2005. Counter-terrorism for emergency responders, CRC Press, US Cheremisinoff N. P. 2001. Practical guide to industrial safety: methods for process safety. CRC Press, US Cote A. 2004, Fundamentals of Fire Protection, Jones & Bartlett Publishers, US Crompton T. R. 2006. Polymer reference. Rapra Publishing, UK Davletshina T. 1998. Industrial fire safety guide, William Andrew, US Fitzgerald R. W. 2004. Building fire performance analysis. John Wiley and Sons, UK Friedman R. 2008. Principles of Fire Protection Chemistry and Physics, Jones & Bartlett Publishers, US Furness M. & Muckett M. 2007. Introduction to Fire Safety Management, Butterworth-Heinemann, UK Garcia K., Kauffmann R., & Schelble R. 2006. Positive pressure attack for ventilation & firefighting, PennWell Books, US Haessler W. M. Fire: fundamentals and control, Volume 16 of Occupational safety and health, CRC Press, US Karlsson B & Quintiere J. G. 2000. Enclosure fire dynamics, CRC Press, US Kolko D. J. 2002. Handbook on firesetting in children and youth. Academic Press, US National Research Council. 1997. Committee on Aviation Fuels with Improved Fire Safety. National Academies Press, US Norman T. 2001. Fire hazards in industry, Elsevier, UK Mannan S. & Lees F. P. , 2005. Lee's loss prevention in the process industries: hazard identification, assessment, Elsevier, US Olien R. 2004. Temperature Our Physical World, Capstone Press, US Rapra Technology. 1996. Polymer testing '96: the Second International Conference on the Testing of Polymers, Rapra Publishing, UK Robbins E. 1986, The Guide to Knowledge, D. Appleton Co., US Saxena J. 1993. Hazard assessment of chemicals, CRC Press, US Stollard P. & Abraham J. 1999. Fire from first principles: a design guide to building fire safety, Taylor & Francis, UK Totten G. E. & Reiche J. 1996. Fire resistance of industrial fluids, Volume 1284 of ASTM special technical publication, Fire resistance of industrial fluids, ASTM International, US Read More