Fire Resistance Testing - Assignment Example

Student’s Name Professor’s Name Course Name/Code Date Design Assignment on Fire Safety Part A of the Assignment Fire Resistance Testing The aim of fire testing is majorly to determine the ability of a structure or a building construction to withstand a particular temperature when it is exposed to fire at a given pressure at a given time and still retains its separating functions (Barraclough, 31). The test might be carried out on any given building component such as the doors, beams, columns and the walls. Any section that is to be tested for example the wall is placed on the direction of interest either horizontally or vertically in an oven. Temperature devices that record the temperature are then placed on the outside on the outside of the material which eventually records the temperature of the mixture. The walls are penetrated by the flames and all the walls that have no protection collapse while those with protection still retain their strength and will eventually remain firm as they were before. Reaction to Fire Testing Several authors have given different approaches to the definition of reaction fire testing one of which states fire reaction testing as the rate at which a system has either a direct or indirect contribution to the development of the fire and the rate at which the fire may spread from one point to another within a compartment of a building or outside the building environment. Reaction to fire testing is a major phenomenon which is mainly witness during the initial stages of fire breakout either within a building compartment or outside a building environment which is occupied by a number of people who need to be rescued. The approach that is employed to rescue within a fire infested area determines the ease with which people vacate the area in question or the rate at which people get rescued. There must be laid down building regulations that makes it so easy for people to vacate such places in case of emergency situations. These regulations include such factors as the stairs and the well designed lifts for emergencies. Flammability Limits According to Rasbash, flammability limits are the ranges in pressures and temperatures with respect to their compositions which may result into responses of explosions when other factors majorly the external ones are employed into use (40). The limits are due to the degree of concentration that exists between the fuels at given temperatures and pressures in which it is exposed. The type of ignition and the strength of the ignition are major contributing factors to the flammability limits. The higher the ignition the higher the flammability limits and the lower the strength of ignition the lower the flammability limits. Flammability limits can also be dictated by the type of the atmospheric pressure for example the flammability limit is much higher in oxygen than it appears in a free air (61). The history illustrates that in most of the cases, the fire hazards are caused by the toxic gases and the most predictor of the fire hazards is the rate at which heat is released into the compartment or the mixture while the toxicity of the burning mixture contributes to a lesser significance and even the Bunsen burners also contribute to a lesser significance aftermath on the fire hazards. Several analyses can be used to determine the fire safety of a performance based design. In this case, we are going to look at the deterministic analysis in which a given number of representative fire scenarios are then analyzed followed by a thorough quantitative description. The heat release rate, the available toxic species and also the rate of the smoke that is being produced majorly defines the design fire in most of the times within a compartment. These factors help an individual or group of individuals in selecting the best fire design which is considered the best resource for all or any personnel that works in any sector involving the fire designs. Factors Influencing Fire Development & Rate of Fire Growth in a Compartment 1. The surrounding environment of a compartment The rate at which the flame spreads increases with temperature for example, as the ambient temperature increases, the rate at which the flame spreads also increases. For this to be achieved, the material is first heated up especially its surface until a specific ignition temperature is reached or attained. Monitoring the flame spread, it will be noted that the rate at which the spread occurs is in correlation to the rate at which the temperature increases from the beginning of the experiment. With the availability of the combustible gases, it is noted that the burning rate of a material also increases for example, the combustible gases increase as the surface of the material is heated up and it decreases as the surface of the material is cooled down. 2. The Fire location and Surface geometry of a compartment When different surface geometries are considered, it is noted that there is always an interaction that is experienced between the two surfaces especially the burning surfaces. The smaller the geometry between the burning surfaces the higher the rate in which the fire spreads and the wider the geometry, the slower the rate in which fire. The flame spreads very fast with decrease in the angle. This is because the materials are closer to one another which ease the rate or the ease with which it moves from one material to another. Also, decrease in angle makes heat to get trapped so easily within the corner making the material to get heated up rapidly hence increasing the rate at which the fire spreads within the compartment. The equation relating these can be given by; q = εσΤ4 Where q is heat flux, ε is the emissivity, and σ is the Stefan Boltzmann constant 2. The rate at which Oxygen is supplied to the compartment/ The Ventilation Factor and Burning Regime. When fire within a compartment burns in a well ventilated place, the rate at which it spreads is higher as compared to the rate at which it spreads in a poorly ventilated compartment. When any part of the compartment either the door, window or the wall is broken which allows more air or the oxygen to enter the compartment, it is realized that the rate of spread is much higher and when this mixes with fuel rich hot gases, a sudden increase in combustion and the rate of spread to be higher. The larger the ventilation openings within a compartment, the faster the rate of fire spread and vice versa. This is strongly in correlation with the below expression m = 55Av v kg/s) Where m is termed as the burn rate, A is the total area in a compartment and H is the compartment height. 3. Boil over The boil over may be defined as a phenomenon which is realized when a fluid like water is sprayed on a burning liquid or burning material which is less dense, and with a boiling temperature which is higher than that of the water. When water is sprayed over a burning material of much higher temperatures, its component is split into hydrogen ions and O+ .The oxygen part then promotes further burning and the spread of the fire within a compartment. Water droplets falling through the surface may then become ‘instant’ vapor, with a very significant expansion that may cause the spraying out of the liquid fuel. The increase of the area fuel spray creates a rapid increase in the fire. This may not really happen at the surface but may also occur at the collection of the denser water at the bottom of a fuel tank then suddenly boil as the fuel mixture recedes to the bottom which translates to the term ‘boil over’. 4. Fuel supply within a compartment The amount of fuel being supplied into a compartment really determines the rate at which fire spreads within the compartment. To reduce the rate of spread, the amount of fuel flow or supply into the compartment must be reduced otherwise the fire spreads tremendously (Hasofer and I D, 09). Considering the codes of practice, and building regulatory documents, there must be minimal supply of any flammable fuel into a compartment to facilitate safety within the building. The materials must be tested in specific standard fire tests which can eventually be classified under different classes of class 0 to class 3. This is majorly with respect to the surface flame performance. PART B of the Assignment 1. Five Functional Requirements of Approved Document B a. Spread of fire externally b. Spread of fire internally as a result of the linings c. Spread of fire internally due to the structure d. The access and even the facilities used for the purpose of fire service e. The means both warning and escape 2. Means of Escape from Fire Approved Document B defines means of escape as any structure or device that is meant for exits during emergency when there is fire. Requirements of Safe Means of Escape from a Building Safe means of escape from a building enclosure requires alternative means of escape. It also requires the escape route to be directed to a place of safety or allow access to place of relative safety. The document also outlines that the stairway should be protected. The travel route should be reasonable and there should be a single direction of escape. 3. Maximum Recommended Size of Compartment Single storey shop with sprinkler protection Single storey industrial unit There is no limit of floor height of top storey for the building that is above the ground level. Further, there is no limit for the floor area. For an industrial unit of a single storey that is not sprinkled or sprinkled, maximum height is 18m and no limit in terms of floor area. 4. Maximum size of an opening (unprotected area) discounted for space separation between buildings The separation of the building from the boundary should be at least 2 m between the boundary lines. 5. Fire-fighting shaft and Fire fighting lift under the following circumstances a) An office building with a top occupied floor of 250m2 located at 19m above fire service vehicle access level Both the fire-fighting shaft and the fire-fighting lift can be used in such a situation both as means of escape and to assist the fire fighters in accessing the facility. b) A four storey assembly building with a top storey of 1400m2 located 10m above fire service vehicle access level However, for a building that is located 10 m above the fire service vehicle, a fire-fighting shaft and lift are not necessary. For 10 m height, the fire fighting shaft and lifts may not be required. 6. Minimum Recommended Fire Resistance Periods a) A 35m high sprinkler protected residential building Answer: 30 minutes b) A four storey shop with sprinkler protection Answer: 60 minutes 7. Purpose groups appropriate for different premises a. A students union building Answer: Group 2(a) residential (institutional) purpose group b. A department store Answer: Group 7 (a) storage & other non-residential c. A factory Answer: Group 6, industrial purpose d. A swimming pool building Answer: Group 5 for assembly & recreation 8. Recommended travel distance limitations for (single direction & more than one direction) according to Table 2 of ADB: single direction more than one direction A normal hazard storage facility 25m 45m A place of special fire hazard 9m 18 m The bedroom of an apartment 9m 18 m A lecture theatre with fixed seating in rows 15m 32 m Shop floor 18 m 45 m Plant room that exits through the accommodation within a building 9m 35 m 9. Recommended minimum number of escape routes from a storey (According to Table 3 of ADB) Number of People Escape Routes 10 1 200 2 450 2 650 3 10. Minimum exit width that is required to accommodate ( According to Table 4 of ADB) Number of People Minimum Exit Width (mm) 219 1050 61 850 10 750 500 people 5 mm per person 11. Minimum width of the escape stairs for a building with four above ground floor and served by two escape stairs without lobby protection (According to Table 7 of ADB) Number of persons Minimum Width of the Escape Stairs 75 1000 mm 130 1200 mm 12. Minimum width of the escape stairs for each floor of a building with five above ground floors is served by three escape stairs with lobby protection (According to Table 7 of ADB) a. 155 persons Answer: 1500 mm b. 230 persons Answer: 1800 mm 13. If the number of occupants from ground floor is 100 occupants, then final exit should accommodate 81 persons + 100 persons = 181 persons. Thus, exit width = 1050 mm 14. Floor space factors for different areas (According to Table C1 of the ADB) a. An office Answer: 6 m2/ person b. A bar Answer: 0.3 m2/ person c. A shop Answer: 2.0 m2/ person d. A students union Answer: 1.0 m2/ person 15. Number of occupants by use of the floor factors obtained in Question 14 and the minimum number of exits required and minimum width of each exit. Room dimensions: 40 m x 40 m Area = 40 m 40 m = 1600 m2 Therefore, number of occupants will be determined by floor space factors as shown: An office = persons A bar = persons A shop = persons A students union = persons 16. Meaning of terminology: Life safety Life safety refers to the sufficient measures aimed at limiting any harm to persons as a result of heat, firefighting waters or smoke. Property protection Protection of property takes into consideration all the standards that reduce damage to the fabric of the building, its content or disruption of business due to heat, smoke or water used for fire fighting. Fire resistance Fire resistance is the ability of the elements used in construction to withstand the fire effect associated with fire penetration, a lot of heat transfer and collapse. Cavity barrier Any construction element whose aim is to restrict spread of smoke and fire through the cavities is known as a cavity barrier. 17. Estimate for internal room sizes with references to Fig 1 and Fig 1a. Approximate areas of each room = 5 x 5 = 25 m2 Travel distance from each room and floor Since the layout for all the floors is same, then the travel distance to exit is as follows: 5 m + 5 m = 10m for rooms near exit, followed by 10 m + 5 m = 15 m, then 15 m + 5 m = 20m, 20m + 5 m = 25 m and finally 25 m + 5 = 30 m Occupancy load The occupancy load is determined by the nature of the premise. This layout indicates a business premise and the occupant load for such premise is 1 person per 100 square feet of the total floor area. This layout suits purpose group 4 for shop and commercial Exit width and the final exit width The total area of the floor is: Occupancy load If the occupancy load is 1 person/ 9.2m2, then per floor, the number of occupants is 250/9.2 = 27 individuals and for three floors it is 27 x 3 floors = 81 persons for entire building. Number of occupants per floor = 250/9.2 = 27 persons For all the floors = 27 x 3 = 81 persons For 81 persons, the exit width is 1000 mm, final exit is 1800 mm, and stair width is 1000 mm. 18. Walls and Ceiling Linings’ Classification Linings fall under different classifications. For instance, small rooms have an area not exceeding 4 m2 whereas the area for domestic garages does not exceed 40m2. The classification also takes into consideration the other rooms and circulation spaces within the house dwellings. References Top of Form Top of Form Top of Form Approved Document B. London: NBS/RIBA Publishing, 2007. Print. Bottom of Form Top of Form Barraclough, Sue. Fire Safety. Oxford: Heinemann Library, 2007. Print. Top of Form Hasofer, A M, V R. Beck, and I D. Bennetts. Risk Analysis in Building Fire Safety Engineering. Amsterdam: Butterworth-Heinemann, 2007. Print. Top of Form Rasbash, D. Evaluation of Fire Safety. West Sussex, England: J. Wiley & Sons, 2004. Print. Bottom of Form Bottom of Form Bottom of Form Bottom of Form Read More