Engineering Design Practice - Assignment Example

ENGINEERING DESIGN PRACTICE Customer Inserts His/Her Name Customer Inserts Grade Course Customer Inserts Tutor’s Name Insert Date Here (Day, Month, Year) 1. Give a definition of fire, include an appropriate diagram. Fire is a rapid chemical change which results in the emmittance of flame, light and heat due to exothermic oxidation brough about on a combustible substance, which could be anything apart from or more than bruning fuel. 2. Identify the different stages of fire growth, include an appropriate diagram. Four stages are involved in development of fire, and these are: - Incipient stage: This is accompanied by very little heat, practically no smoke and nom flame. Smell comes from combustible particles. - Smoldering stage. Smoke is there, but sans flame and has a little heat. - Flame stage. Flame is there, heat, less or no smoke. - Heat stage. Too much of heat is present; flame, toxic gases and heat are produced. The fire moves with a quick transition hereafter. 3. Explain the difference between pre-mixed and diffusion flames, and provide some practical examples of each. Fuel and oxidizer are mixed before reaching the flame in a premixed flame. The stoichiometry of the mixture can be regulated by changing the fuel to oxidized ratio, and by using an inert gas like nitrogen to act as a substance that can dilute the reactants. This also can alter the flame temperature. On the contrary, only fuel is supplied to the burner in a diffusion flame. Ambient air supplies the oxidizer. That apart combustion and mixing happen together. 4. What are the 5 functional requirements of Approved Document B? The requirements are: 1. Well-defined ways of escape and warning so that reaction time to get away or get saved from the fire is too quick. 2. Load bearing element should be defined by internal fire spread structure, and so should be the nature of fire resisting compartmentation. 3. The internal fire spread (Lining) B2, or internal fire spread, should clearly identify the areas in the building that must be furnished as part of standard classifications 4. There must be enough guidance as provided by external fire structure for the roof coverings and fire resistance of external walls. 5. There are two broad standards for the design methods of fire resistance of buildings: This depends on a number of factors which includes material used, the architecture of the building, soil on which it is built, the elements used, thickness of fire protection material used and many more constructions intricacies. Aesthetic is kept into consideration too. 6. What are the two categories of fire testing? Explain the difference between them. Fire testing has been classified into two categories. One measures igbnition and subsequent spread of flames from one area/ portion of the object on fire to another. And measures resistance of fire; in other words this test actually tells how long and which way can a structure withstand a fire. 7. Why is it important to carry out more than one experiment to test the same parameter? This is important so as to ensure that the parameters set thereafter are correct and reliable and from experimental errors. Doubts get removed by multiple testing and also are helpful in conducting tests under different conditions. The guidelines are more trustworthy that are derived from multiple testing. 8. What factors influence the severity of a fire within a compartment? There are many, but the following are notable: 1. Density and distribution of fire load type 2. The type of combustible on fire and its behaviour 3. How big or small is the compartment 4. The type of ventilation it has 5. Thermal conductivity of the compartment material or boundaries 9. How is heat transferred in a compartment fire? Include a diagram. This happens by an intricate interplay of the object on fire, the heat it generates, the gases present in the compartment and the level of compartment confinement. When burning object rises to transform itself into hot gas, that in turn rises to the ceiling which heats up everything around. More the heat, more is the spread of fire. 10. Explain the term "flammability limits". The definition is with regard to the combustible proportion gases in a mixture and how flammable is it. There are certain conditions under which gas mixtures are flammable. If the limit is lower, it is called lower flammable limit (LFL), if it is more it is called upper flammable limit (UFL). UFL results in richest flammable mixture, while LFL is just the opposite. 11. Draw a graph/ diagram to illustrate the flammability limits of flammable vapors. 12. Define the term "limiting oxygen index". Limiting oxygen index is defined as the minimum concentration of oxygen in the oxygen and nitrogen mixture. 13. What does it mean if a sample has a high LOI or a low LOI? The first one means that there is better flame retardancy factor or LOI, on the other hand, means that chances of flame reduction are low. A substance with high LOI means that it would burn with difficulty, while contrary is true for low LOI. 14. Explain the ignitability test? This is used to determine glow fire ignitability temperature. This takes into consideration three crucial. 15. The cone calorimeter can be used to measure a number of different parameters from experimental fires, what are they and which one is the most important in determining the fire hazard performance of materials? A cone calorimeter does the following measures ignition time, mass loss, combustion products, heat release rate and other parameters which are significant to burning. The calorimeter exposes different itself to different heat fluctuations over its surface. 16. What are the criteria for when flashover will occur The is the extreme and the end point of any fire. In a typical flashover everything is on fire and since everything is on fire, it engulfs everything else. There is complete chaos in terms of fire and everything is filled with red hot flames. The temperatures in a flashover can reach as high as 650 degrees 17. Once ignition has occurred what is required to maintain combustion? The fire triangle illustrates the relationship between the three basic elements needed to establish fire: oxygen, combustible fuel, and heat to initiate and sustain combustion. These three elements combined together in the proper ratio lead to fuel ignition and combustion. 18. What are the basic two types of uncertainty found in measurements? Give an example of each. The two types of uncertainties found in measurements are Type A and Type B. Type A is random uncertainties indicated by repeating measurements. Type B elements are identified on the basis of scientific judgment using all the available information including manufacturer’s details, data provided in calibration reports and knowledge of the measurement process. 19. Test 1 2 3 4 5 6 7 8 9 10 Heat Release Rate @ 25.00kW/m2 44.80 42.15 42.97 43.60 43.88 44.80 42.79 45.10 41.62 43.74 Range 41.62 - 45.10 Mean = 43.54 Standard Deviation 20. In the table below there is a set of results obtained from the "Bang Box" experiment. Plot a graph which will best show your results and state what the results show. 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 21. What are the four main classes of ignition? The four main classes of ignition are 1. Human carelessness 2. Natural phenomenon 3. Technological failure 4. Deliberate fire raising 22. In relation to the characteristics of building materials give definitions for the following terms: Combustibility means how combustible is the material Fire propagation is extent by which fire propagates Fire resistance is resistance of a structure to withstand fire Surface spread of flame is affected by the moisture content of the material. 23. Explain what the two major mechanisms of burning are. Two mechanisms of burning are solid phase glowing combustion and gas phase flaming combustion 24. How can fire spread between buildings? It can spread by multiple behavior that includes radiation, object to object combustion, convective heat transfer and simply by spread of flames. 25. Define the term "fire plume". Identify and explain the different regions within a fire plume. Fire plume is actually a model designed to simulate air quality impacts and atmospheric dispersion from fires. It predicts the following: 1) instantaneously discharged thermals, 2) fires that generate hot continuous plumes 3) smoldering or decaying fires. REFERENCES Brown D.F.,Dunn W. E., Lazaro M. A.and Policastro A.J., 1999, Contributed paper from the modeling session from the joint Fire Science Conference and Workshop. Scire J.S., Strimaitis D. G., Yamartino R. J., 2000, “ A User’s Guide for the CALPUFF Dispersion Model v. 5” Chang J.C., Scire J.S., 1999, “ User’s Guide to the EPM2BAEM Interface Program” Dennis A., 2000, Inventory of Air Pollutant Emissions Associated with Forest, Grassland and Agricultural Burning in Texas, MS Thesis, University of Texas at Austin. ENVIRON, 2000, “User’s Guide Comprehensive Air Quality Model with Extensions (CAMx) version 3.10” Weil. J.C. (1988) Plume Rise, in Lectures on Air Pollution Modeling, A. Venkatram and J.C.Wyngaard (eds.), American Meteorological Society, Boston, 119-157 Read More