Scientific Principles for Fire Professionals - Assignment Example

Scientific Principles for Fire Professionals Name Institution Name Course Name and Code Date 1. Explain, with the help of a fire cycle diagram, the fundamental physiochemical processes during the thermal degradation and combustion of a polymeric material. Numerous polymers undergo self-sustainable combustion if there are suitable ignition sources and presence of oxygen or air. The main sources of ignition are non-polymeric materials, such as electric arcs, torches, cigarettes and matches (Mousavi, Bagchi, and Kodur, 2008). Moreover, polymers are associated with propagation of fire. In burning the polymer, numerous combustion processes takes place (Laoutid et al., 2009). The chemical reactions occur interdependent, which follows a condensed phase, the interface between the gas phase and condensed phase and the last phase is the gas phase. The combustion of a polymer follows a cycle format, which starts with polymer heating, decomposition, ignition and combustion (Babrauskas, 1990). The heating cycle starts with the polymer been heated to a specific temperature and it begins to decompose resulting in emissions, which advance the combustion processes (Joseph and Team, 2007). In the flame zone, the products diffuse and may undergo further combustion resulting in liberation of more heat. When the burning conditions are maintained, the heat produced is then transferred to the polymer surface, which sustains the combustion cycle (Mousavi, Bagchi, and Kodur, 2008). The following image summarizes the combustion of a polymeric material. Source: (NTIS, 2004). The decomposition of polymers involves physical and chemical processes. The chemical processes result in the emission of flammable volatiles while physical changes, such as charring and melting, which can alter the burning and decomposition characteristics of material; for example, heating a solid polymer result in the emission of varying amounts of solid residues and volatile products (Laoutid et al., 2009). The residues can be inorganic, carbonaceous or a combination of both. Numerous fire tests have shown that carbonaceous formation contributes to flame redundancy, but the formation of the structure of carbonaceous has not been documented (Li and Stoliarov, 2013). Based on some studies, burning the polymers below 550o C decomposes to primary char, tars, and fuel gases. Heating the polymers at a temperature above 550o C, the primary char is transformed into small graphitic regions, which is different from the original polymers structures. Other researchers have presented that the carbonaceous formation of polymers includes graphitization, turbostratic char formation, aromatics fusion, aromatization and cross-linking (Joseph and Team, 2007). Numerous chemical reactions such as redox reactions, Friedel-Crafts chemistry, Lewis acid catalysis, utilization of additives and graft copolymerization promotes the formation of char. 2. Give a detailed account of the fire hazards associated with combustible materials. Fires generate three sources of hazards, which are depletion of oxygen, smoke, and heat. These sources of hazards can contribute to the fire incident in different ways but depends on the oxygen supply, fuel source, and heat release rate. Heat is the most common hazard associated with combustible materials (Joseph and Team, 2007). Even though numerous deaths may be associated with smoke inhalation others are caused by the heat burn. The inhalation of heat affects the upper airway and oropharynx while excessive heat can even burn bronchioles. Oxygen depletion causes hyperventilation on an individual. If the oxygen interruption last more than three minutes, the individual suffers irreversible damage (Joseph and Team, 2007). The rate of oxygen depletion and resulting complications are associated with numerous physical characteristics of the environment and the fire; for example, availability of air supply and fire size (Laoutid et al., 2009). The major issue is not the depletion of oxygen rather the consequences of the fire such as the occurrence of flashover (Mousavi, Bagchi, and Kodur, 2008). Flashover results in depletion of oxygen over a large area, which contributes to larger hazards. Smoke can be defined as all the byproducts from a fire incident including the combustion of materials and pyrolysis (Mousavi, Bagchi, and Kodur, 2008). Smoke usually consists of free radicals, aerosols, organic molecules, gases and particles. The amount of smoke contributes to overall hazard associated with the combustible materials. Water is released during combustion, and it can be used to transport absorbed chemicals, such as hydrochloric acid (Hartzell, 2001). Aerosols and soot are the visible smoke components. The smoke affects the lungs of the individuals, cause air pollution, vision impairment, lacrimation, irritation of the eyes and speeds up the fire incident. Nevertheless, the smoke can be used as a cue for fire meaning the occupants can escape before the fire worsens. Breathing smoke that contains hydrophilic pyrolysates can cause edema and can damage respiratory membranes (Mousavi, Bagchi, and Kodur, 2008). During the combustion period, different types of gases are emitted. The gases include carbon dioxide, carbon monoxide, and hydrogen cyanide, among other gases. These gases also affect the respiratory system and may limit the movement of people within the structure or vicinity. From a completely different angle, it is important to analyze the socioeconomic and environmental consequences of the hazards. If the fire incident occurred in a business building, issues of business continuity are raised. Moreover, different stakeholders will suffer economic costs and consequences. People will lose businesses while the governmental institutions will be required to provide resources to address the hazard (Laoutid et al., 2009). The people working in the building will lose employment, and other stakeholders will not have a source of income. The environment will be degraded because of emission of different pollutants to the ecosystem. Some common sources of pollution include sound, air and water contamination (Joseph and Team, 2007). Hence, the consequences of hazards and huge but also depend on the source of ignition, the burning materials and other components that influence the burning (Mousavi, Bagchi, and Kodur, 2008). Therefore, to prevent these problems, fire safety measures should be integrated into the designing and constructing of buildings and other structures. 3. Briefly, describe the various medium and large-scale prescriptive flammability tests. Comment about correlations, if any, between these tests a. The cone calorimeter test The cone calorimeter test employs a bench scale test to analyze the reaction of fire on a surface lining materials (Mousavi, Bagchi, and Kodur, 2008). The design of the test consists of numerous apparatus including a gas collection system, an ignition source, and an electric heater. The following image summarizes the physical assembly of different apparatus: Source: Horrocks and Price (2001, p. 359) b. The room corner test The room corner test is a method that is used in the measurement of burning behavior of materials used in the surface lining in buildings (Laoutid et al., 2009). It is a large-scale test method, and the apparatus used consists of a small compartment with a gas collection system and one open door, with other instruments used to measure the fire gas properties (Joseph and Team, 2007). The following image summarizes the room corner test measurement method: Source: Horrocks and Price (2001, p. 358) On the three walls, a lining material is mounted while the ceiling is exposed to fire, which is strategy placed on the end corners. The usual measures of the compartments are 2.4 m (length), 2.4m (height) and 3.6m (width), and 2.0 high and 0.8 m wide size of other openings. The non-combustible material is used in the construction of the walls, the floor, and the ceiling. The ignition source is a propane burner that is burned for 10 minutes at 100 kW and after the ten minutes, the output level is adjusted to 300 kW, which is also exposed for 10 minutes. The burning will be continued until a flashover situation occurs. Some of the recorded information includes oxygen depletion rate, carbon dioxide production rate, carbon monoxide production rate, smoke production rate and heat release rate (Schartel and Hull, 2007). c. The single burning item test The Single Burning Item is a test method that is used to determine the reaction to fire behavior of building materials. The analysis is aimed at exposing the building products to a single burning thermal attack. The approach is mounting the specimen on a trolley that is located on a frame, which is under an exhaust system (Reed and Cichanowski, 1994). The specimen reaction to the burner is monitored visually and instrumentally. Smoke and heat release rates are instrumentally measured while the physical characteristics are analyzed through observation (Laoutid et al., 2009). The specimen is analyzed for 20 minutes and through the use of oxygen consumption calorimetry, the heat release rate is measured. Based on the attenuation of the light, the smoke production rate is also measured (Joseph and Team, 2007). The flaming droplets are also observed within the first 600 seconds while the lateral flame is observed, and the height should be between 500 and 100 mm. Further classification of SBI parameters test includes total heat release, lateral flame spread, fire growth rate index, total smoke production, and smoke growth rate index. d. The Limiting Oxygen Index (LOI) The limiting oxygen index (LOI) is used to estimate the minimum oxygen concentration, which can support polymer combustion (Reed and Cichanowski, 1994). The concentration is measured through passing a mixture of nitrogen and oxygen over a polymer specimen, and the amount of oxygen reduced until a critical level is reached (Joseph and Team, 2007). To improve the capability of the different plastics reading, standardized tests are used to obtain LOI, which includes ASTM D2863 and ISO 4589. e. Underwriters Laboratory test (UL-94) UL-94 is a test that is utilized in determining the flammability of plastic material, which is used in electronic devices parts. The test was created and is been utilized by Underwriters Inc. which has numerous branches across the world and the test is used to test and examine materials, systems and devices (Reed and Cichanowski, 1994). In addition, the technique enables identification of hazards and material properties. The test contains numerous small-scale tests procedures, which has parameters used for testing the polymers (Joseph and Team, 2007). The data obtained is quantitative, and the data is based on material burned within a given time and “afterflame” time. Afterflame is defined as the time in which the material continues to burn after removal from the heat source, and it is usually measured in seconds. The material burned defines the sample length that burns in a given period. The UL 94 has six different flame tests, but four are commonly used. In performing the test, defined time, control heat source and standard specimen are required. References Babrauskas, V., 1990. Heat release in fires. London: Taylor & Francis. Hartzell, G.E., 2001. Engineering analysis of hazards to life safety in fires: the fire effluent toxicity component. Safety Science, 38(2), pp. 147-155. Horrocks, A.R. and Price, D. 2001. Fire retardant materials. London: Woodhead Publishing. Joseph, G. and Team, C.H.I., 2007. Combustible dusts: A serious industrial hazard. Journal of Hazardous Materials, 142(3), pp. 589-591. Laoutid, F., Bonnaud, L., Alexandre, M., Lopez-Cuesta, J.M. and Dubois, P., 2009. New prospects in flame retardant polymer materials: from fundamentals to nanocomposites. Materials Science and Engineering: R: Reports, 63(3), pp. 100-125. Li, J. and Stoliarov, S.I., 2013. Measurement of kinetics and thermodynamics of the thermal degradation for non-charring polymers. Combustion and Flame, 160(7), pp. 1287-1297. Mousavi, S., Bagchi, A. and Kodur, V.K., 2008. Review of post-earthquake fire hazard to building structures. Canadian Journal of Civil Engineering, 35(7), pp. 689-698. National Technical Information Service (NTIS). (2004). Fire-Safe Polymers and Polymer Composites. Retrieved from http://www.fire.tc.faa.gov/pdf/04-11.pdf Reed, C.W. and Cichanowski, S.W., 1994. The fundamentals of aging in HV polymer-film capacitors. Dielectrics and Electrical Insulation, IEEE Transactions on, 1(5), pp. 904-922. Schartel, B. and Hull, T.R., 2007. Development of fire‐retarded materials—Interpretation of cone calorimeter data. Fire and Materials, 31(5), pp. 327-354. Read More

Oxygen depletion causes hyperventilation on an individual. If the oxygen interruption last more than three minutes, the individual suffers irreversible damage (Joseph and Team, 2007). The rate of oxygen depletion and resulting complications are associated with numerous physical characteristics of the environment and the fire; for example, availability of air supply and fire size (Laoutid et al., 2009). The major issue is not the depletion of oxygen rather the consequences of the fire such as the occurrence of flashover (Mousavi, Bagchi, and Kodur, 2008).

Flashover results in depletion of oxygen over a large area, which contributes to larger hazards. Smoke can be defined as all the byproducts from a fire incident including the combustion of materials and pyrolysis (Mousavi, Bagchi, and Kodur, 2008). Smoke usually consists of free radicals, aerosols, organic molecules, gases and particles. The amount of smoke contributes to overall hazard associated with the combustible materials. Water is released during combustion, and it can be used to transport absorbed chemicals, such as hydrochloric acid (Hartzell, 2001).

Aerosols and soot are the visible smoke components. The smoke affects the lungs of the individuals, cause air pollution, vision impairment, lacrimation, irritation of the eyes and speeds up the fire incident. Nevertheless, the smoke can be used as a cue for fire meaning the occupants can escape before the fire worsens. Breathing smoke that contains hydrophilic pyrolysates can cause edema and can damage respiratory membranes (Mousavi, Bagchi, and Kodur, 2008). During the combustion period, different types of gases are emitted.

The gases include carbon dioxide, carbon monoxide, and hydrogen cyanide, among other gases. These gases also affect the respiratory system and may limit the movement of people within the structure or vicinity. From a completely different angle, it is important to analyze the socioeconomic and environmental consequences of the hazards. If the fire incident occurred in a business building, issues of business continuity are raised. Moreover, different stakeholders will suffer economic costs and consequences.

People will lose businesses while the governmental institutions will be required to provide resources to address the hazard (Laoutid et al., 2009). The people working in the building will lose employment, and other stakeholders will not have a source of income. The environment will be degraded because of emission of different pollutants to the ecosystem. Some common sources of pollution include sound, air and water contamination (Joseph and Team, 2007). Hence, the consequences of hazards and huge but also depend on the source of ignition, the burning materials and other components that influence the burning (Mousavi, Bagchi, and Kodur, 2008).

Therefore, to prevent these problems, fire safety measures should be integrated into the designing and constructing of buildings and other structures. 3. Briefly, describe the various medium and large-scale prescriptive flammability tests. Comment about correlations, if any, between these tests a. The cone calorimeter test The cone calorimeter test employs a bench scale test to analyze the reaction of fire on a surface lining materials (Mousavi, Bagchi, and Kodur, 2008). The design of the test consists of numerous apparatus including a gas collection system, an ignition source, and an electric heater.

The following image summarizes the physical assembly of different apparatus: Source: Horrocks and Price (2001, p. 359) b. The room corner test The room corner test is a method that is used in the measurement of burning behavior of materials used in the surface lining in buildings (Laoutid et al., 2009). It is a large-scale test method, and the apparatus used consists of a small compartment with a gas collection system and one open door, with other instruments used to measure the fire gas properties (Joseph and Team, 2007).

The following image summarizes the room corner test measurement method: Source: Horrocks and Price (2001, p.

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