The Design Methods of Fire Resistance of Buildings - Assignment Example

1. Give a definition of fire, include an appropriate diagram. A fire is a progression of rapid chemical reaction among the three elements which are also basics of life i.e. oxygen, thermal energy and fuels. A substance catches fire when the thermal energy in combination with oxygen transfers from hot substances to the cooler ones, leading them to each their burning point. 2. Identify the different stages of fire growth, include an appropriate diagram There are a number of stages involved in the development of fire 1. Detonation 2. Growth 3. Flashover 4. Entirely developed 5. Decaying phase 3. Explain the difference between pre-mixed and diffusion flames, and provide some practical examples of each. In a premixed flame the reactants are well mixed up and burn when the mixture is raise to a sufficiently high temperature on the other hand in diffusion flames the reactants are of separate origins. A Bunsen flame is a practical example of pre-mixed flames. Most of the industrial fires are good example of diffusion flames. 4. What are the 5 functional requirements of Approved Document B? The five serviceable necessities of Approved Document B are as follows: i. The provisions of fire alarms, fire exits and adequate life security measures are necessary to be considered into the blueprints of a construction. ii. It is necessary to adopt building materials of fire resistant properties that should sufficiently resist the fire and slow the process of intensifying. iii. The structure of the building should be strong and stable enough to hold the load of burning structure for maximum time to facilitate the agencies minimize the losses. iv. The materials used in the outdoor lining of the building is ought to be of fire resistant nature in array to avoid any risks to the adjoining structures. All the aspects like height, position and utilization is must to be considered while planning. It is necessary that the construction should cope with the minimum space required by the fire fighting agencies to conduct a rescue operation in case of hazardous situation. v. The structure is required to offer enough space for the entry of large fire equipments into the building. 5. There are two broad standards for the design methods of fire resistance of buildings: prescriptive and performance-based. Explain the difference between them Prescriptive method exemplifies a structural inferno plan somewhat precisely in rudiments of the resources occupied, outline and degree of structural fundamentals, intensity of inferno security material and building detail etc. The plan scheme is generally foundational on the performance with corresponding or equivalent preset fire experiments. Though, a performance oriented process for structural inferno resistance plan is analogous to the protocol of scheming construction to airstream loads and seismic impacts. The responsibility of a structural element will be clear-cut and a set of intent tests will be agreed that allots the estimation of fire recitation in relation to the major practical decisive factor. 6. What are the two categories of fire testing? Explain the difference between them The two categories of fire testing are: i. Tests to determine detonation and the surface spread of conflagration in a specific size of area, and ii. Tests to calculate the fire confrontation The major discrimination amid the pair of techniques are fire confrontation tests weigh up a substance’s potential to carry on to preserve its formation for the interval of a fire while, the Tests conducted to weigh detonation timing and conflagration spreading verifies the point in time occupied by the flames to spark off and widen in a specific room. 7. Why is it important to carry out more than one experiment to test the same parameter? The necessity of conducting more than one experiment arises due to the fact that a parameter on a single experiment can test positive as the potential cause of fire but, when it is evaluated by another experiment it may turn out to be not so likely cause of fire. Hence, to fully and correctly establish the cause of fire, the same parameter should be evaluated with more than one experiment. This is supposed to be prepared in array to evade studying the incorrect cause. 8. What factors influence the severity of a fire within a compartment? The factors responsible for swaying the rigorousness of a fire in a compartment are: fire load sort, accumulation and allotment burning performance of the inferno load compartment measurement exposure to air conditions of the compartment Thermal properties of the compartment boundaries 9. How is heat transferred in a compartment fire? Include a diagram In a compartment there are two possible ways through which heat can be transferred – Conductive and Radiation. Conduction is a transport of molecular energy requiring a matter to get transferred while radiation is electromagnetic energy transfer because of possession of thermal energy in a body 10. Explain the term “flammability limits Flammability limits is the “stoichiometric” constituent limits of a lighted oxidizer-fuel fusion what will burn up for an indefinite period at prearranged situations of heat and stress devoid of auxiliary ignition. 11. Draw a graph/ diagram to illustrate the flammability limits of flammable vapors 12. Define the term “limiting oxygen index”. The limiting oxygen index (LOI) is defined as: Where [O2, cr] and [N2] are the bare minimum oxygen absorption in the inflow gas compulsory to pass the “minimum burning length”' decisive factor and the nitrogen concentration in the inflow gases correspondingly. If the inflow gases are sustained at unvarying stress then the denominator of equation~ (1) is stable as any lessening in the fractional pressure of oxygen is unbiased by a equivalent boost in the fractional pressure of nitrogen. Limiting oxygen index is further accounted as a portion to a certain extent than fraction. 13. What does it mean if a sample has a high LOI or a low LOI Elevated LOI in a section indicates better fire retardancy whereas; the lower LOI symbolizes the substandard fire retardancy. The experiment procedure is typically reproducible to an accuracy of “+ 0.5%” and the LOI has been utilized expansively to review the competent flammability of “rubbers, textiles, paper, coatings and other materials” 14. Explain the ignitability test? The ignitability test is executed to conclude how uncomplicatedly a material will rupture into combustion when exposed to a very small flame. The burning actions of the sample are observed for inferno stretch and the pace of a flame elements and drops. The research report takes in information as regards to the experimentation samplings and research outcomes. The succeeding information is provided in the ignitability test report: i. Exposure moment in moment devoted in the examination i.e. 15 or 30 s ii. Category of exposure. iii. “The blaze tip attains the 150 mm mark over the conflagration appliance position and the point at which this become apparent” iv. “the blistering droplets were observed or not, which lite fire to the filter paper in the dish underneath the research model” 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? The parameters are ignition time, mass loss rate, combustion products, heat release rate and other parameters associated with the matter’s burning properties like smoke-specific extinction area, and effective heat of combustion. It also comprises of purpose of rate of development of poisonous gases i.e. “CO, HCL, and HCN.” The obtained results can be utilized for assessment of fire hazard and in predicting the full-scale fire performance, via correlations or through computer fire modeling. 16. What are the criteria for when flashover will occur The flashover is transpired by the rapid emission reaction of heat. Flashover occurs when extensive thermal energy from the rising fire is mesmerized into the upper walls of compartment and in the filling spaces of the compartment, soaring the temperature of the explosive gases and pushing them to their “auto-ignition temperature.” This chain reaction of thermal power in the compartment initiates flashover. The two criteria of flashover are “Heat mixed with Smoke and rollover.” 17. Once ignition has occurred what is required to maintain combustion? Post successful ignition a constant supply of oxygen radiant’s in association with hydrogen and fuel is required to maintain a stable combustion. 18. What are the basic two types of uncertainty found in measurements? Give an example of each. The two types of measurements uncertainty are: i. high temperature discharge rate measurement uncertainty ii. quantitative warning measurement uncertainty 19. 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 @ 25.00kW/m2 44.80 42.15 42.97 43.60 43.88 44.80 42.79 45.10 41.62 43.74 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 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 direct heating Buoyant ignition Frictional heating, and Spontaneous impact 22. In relation to the characteristics of building materials give definitions for the following terms: • Combustibility, • Fire propagation, • Fire resistance, and • Surface spread of flame. Combustibility - the potential of a material to perform as a fuel to aid the progression of burning in the existence of air to discharge sufficient heat energy. Fire propagation – Fire resistance - fire-resistance ranking generally refers to the instance phase for which a spontaneous fire guard system can bear in opposition to a customary fire resistance test. This can be enumerated merely as a computation of time, or it may necessitate a congregation of other decisive factor, relating to other essentials of functionality or sturdiness for rationale. Surface spread of flame – the surface spread of flame term is used to illustrate the burning power of a fire as the fire spreads over a surface via initiating a pre coating of heat by the means of radiation, conduction resulting in discharge of gaseous vapors hence, expanding the incineration zone. 23. Explain what the two major mechanisms of burning are The two major method of flaming are gas phase burning combustion and shining combustion. 24. How can fire spread between buildings? There are a number of ways in which fire could possibly spread between two buildings, which are: Through the connecting shaft between the two structures By the means of radiation of excessive thermal energy to the materials of other building By burning droplets and wind transfer Via flashover 25. Define the term “fire plume”. Identify and explain the different regions within a fire plume Read More