Engineering Design Practice - Coursework Example

Engineering Design Practice Student’s Name Tutors’ Name Course Date Engineering Design Practice Part A 1. What is fire resistance testing? Fire resistance is the ability of an element of load bearing structures in a construction (HM Government, 2010 pp.30). Therefore, tests carried out on these elements of construction or structure and building materials to ascertain their abilities to meet the minimum threshold required for fire resistance capabilities is known as the fire resistance testing. Elements of structures can resist fire mainly through three ways: the ability to resist collapse due to the load bearing elements, the ability resists fire penetration, and the elements of structure can act as an insulator to prevent the transfer of excessive heat from one element or structure to another. Fire resistance standards are based on the British Standards that provide the guidelines for structures and compartments to resist fire fire. 2. What is reaction to fire testing? Reaction to fire can be defined as the measurement of the means by which a material adds to the fire development and its subsequent spread at the early stage of the fire break out (BMTRADA 2013). Therefore, the test carried out on materials to determine their contribution ability to the fire development and spread is known as reactive to fire testing. The test is very crucial in determining how easy it would be for people to escape a fire a breakout because it would reveal the material’s ability to spread fire, energy produced and its flammability limits. This test a mandatory for a compliance with Building Regulations, especially in England, which is covered by the Approved Document B. 3. Discuss the term “flammability limits”. Discuss the effects of temperature on flammability limits. Include diagrams. Source of a combustible material (fuel), air (oxygen), and ignition source must exist simultaneously for fire or explosion to occur. Flammability limits of a combustible material can therefore be referred to as the range of the concentration levels of a combustible material in which it can ignite and bust into a flame in the air. The range of concentration levels falls between the lower flammability limit (LFL) and the upper flammability limit (UFL). These limits dictate the minimum and the maximum concentration of the flammable needed for ignition. The lower flammability limit is the minimum concentration of fuel needed to ignite into fire or explosion. The upper flammability limit is the maximum concentration of fuel needed to ignite into fire or explosion. The term flammability limits is so often used to refer to the highly flammable materials such as gases and vapors that can, at certain temperatures, ignite spontaneously without providing an ignition source. The temperature at which fuel or a high flammable material (vapors or gases) is known as the flush temperature (Chandrasekaran 2010, 4). Hence, temperature does influence the flammability limits of substances or materials directly. Although the effect of temperature may not be mentioned without considering the effects brought by pressure variations, this question will deal only with the aspects of the temperature only. The flammability limits of a fuel change with temperatures. As the temperature increases, the lower flammability limit of a fuel decreases while that of the upper flammability limits increases (Chandrasekaran 2010, 3). However, the flammability range increases continuously as the temperature increases (Chandrasekaran 2010, 3). Below is a sample of a flammability diagram. Generally, a flammability diagram consists of three sides: fuel (methane), oxygen, and a passive agent (Nitrogen mostly used). (CFBT-US LLC 2011) The diagram shows the relationship between the three gases. The stoichiometric line (red in color) shows the ideal mixture of the three gases at which a complete combustion is complete. However, it is not possible to achieve the ideal condition for any combustion. Therefore, along the airline between UFL and LFL provides the range of gaseous mixture (gray color) at which a combustion will take place. 4. Discuss heat release rate in relation to fire hazards. Heat release rate (HRR) is one of the variables in the spread of fire. It is measured in joules per second. It is a major determinant on how the fire develop and spread dangerously within a compartment. It is considered the driving force behind the spread of fire and it respond through a positive-feedback mechanism where heat generated to produce extra heat and the chain continues (Babraukas, 1992). Other variables responsible for fire hazards are directly correlated to HRR. Fire hazards are characterized by toxic gases, smoke, and room temperature among other variables (Babraukas, 19926. All the mentioned variables increases as the HRR increases. In fact, it is the HRR that make fire hazards dangerous because it controls the condition of a fire as it develop and spread from point to another. High HRR increases the temperature of burning fire and enhances heat fluxes conditions that make the fire more dangerous to anyone within the vicinity of the fire. 5. Discuss the factors, which will influence the fire development and the rate of fire growth within a compartment. The fire development and its rate of growth is determined by the factors such as the fuel properties, ventilation within a compartment, the design of the compartment, the room condition, and the location of the fire among other factors (National Institute of Standards and Technology (NIST) 2013). The amount of fuel and oxygen available limit the development and spread of fire within a compartment. At the initial stage of fire development, the fuel combusts as the source is depleted and oxygen is required to ensure a complete or a prolonged combustion to release energy. The energy released increases as more fuel is combusted until the fuel is fully burned the point at which the fire is also fully developed. The energy released will start decreasing as the source of fuel is depleted. With more supply of oxygen, the heated gases will continue to burn and release more energy. the temperature of the fire reduces as the fuel is exhausted and the energy released decreases. Ventilation of the compartment is instrumental is determining the amount of oxygen available to support combustion. A compartment with a proper ventilation will ensure a continuous supply of oxygen into the compartment that would prolong the fire until is fully developed. The size of the compartment also matters in the fire development and spread. Large compartments have the capacity to contain more air that would enhance a fire a spread. Similarly, fire development and spread fast in small compartments because of the short distance to cover within the compartment. PART B 1) What are the 5 functional requirements of Approved Document B? The first functional requirement (B1) is the means of warning and escape that must be provided for fire warnings and safe means of escape in case of a fire breakout (ODPM 2007, 14). The second functional requirement (B2) is internal fire spread (linings). It requires that the internal linings must be able to prevent the spread of fire (ODPM 2007, 61). The third requirement (B3) is the internal fire spread (structure). It requires designing a building structure such that it remains stable during a fire, inhibit the spread of fire between compartments and buildings (ODPM 2007, 67). The fourth requirement (B4) is external fire spread. It requires that both the roof and the external walls of a building should be able to prevent the spread of fire from one building to another (ODPM 2007, 91). The fifth requirement (B5) is the access and facilities for the fire and rescue services. It requires that a building to be designed in such a way that it provides facilities to assist firefighters save lives. In addition, a building site should be accessible for fire fighting equipments (ODPM 2007, 105). 2) Give a definition for the terms means of escape from fire. Outline the main requirements of a safe means of escape from a building. Means of escape from fire is the structural provision where a route or an exits is provided for people to move from one place where there is fire to another safe place (Office of the Deputy Prime Minister (ODPM) 2007, 143). A safe means of escape from a building ensure people’s safety in case of a fire breakout. Therefore, a safe means of escape from a building must include alternative escape routes with protected stairways, people should be able to access exit routes to safety with a reasonable travel distance as per the building regulation, and unprotected areas should allow minimal time before accessing protected areas (ODPM 2007, 16). 3) What is the maximum recommended compartment size for each of the following cases: a) A single storey shop with sprinkler protection No limits on the maximum recommended compartment size (ODPM 2007, 74) b) A single storey industrial unit Whether sprinklered or not, there is no limit on the compartment dimension when the unit is up to 18m above ground level (ODPM 2007, 74). While the issue of a single storey does not apply to industrial units beyond the 18m above ground level (ODPM 2007, 74). 4) What is the maximum size of an opening (unprotected area) that can be discounted when considering space separation between buildings? The position of the relevant boundary from a building wall determines the maximum size of the unprotected area. Therefore, Diagram 46 shows various minimum distance between a relevant boundary with their corresponding maximum size (area) of unprotected area (ODPM 2007, 101). 5) In each of the following cases, state whether a fire fighting shaft is recommended and if so, whether or not a fire fighting lift is also required: a) An office building with a top occupied floor of 250m2 located at 19m above fire service vehicle access level Any floor above 18m above fire service vehicle access level needs a provision a fire fighting shaft that include a fire fighting lift (ODPM 2007, 112). Hence, the office building needs both fire fighting shaft and a fire fighting lift. b) A four storey assembly building with a top storey of 1400m2 located 10m above fire service vehicle access level. A building with a storey of 900m2 or more and located 7.5m above fire service vehicle access level needs a fire fighting shaft without necessarily including a fire fighting lift (ODPM 2007, 112). Therefore, this four story assembly building only needs a fire fighting shaft without a fire fighting lift. 6) What is the minimum recommended fire resistance periods for the following structures: a) A 35m high sprinkler protected residential building The height is above 30m which has a minimum fire resistance period of 120minutes (ODPM 2007, 124). b) A four storey shop with sprinkler protection The height of a four storey building is more than 30m above ground level. Therefore, 120minutes is the minimum recommended fire resistance period (ODPM 2007, 124). 7) What purpose groups would be appropriate for the following premises? (ODPM 2007, 140) a) A students union building (e.g. 53°) Office b) A department store Storage c) A factory Industrial d) A swimming pool building. Assembly and recreation 8) According to Table 2 of ADB, what are the recommended travel distance limitations (single direction & more than one direction) for the following: a) A normal hazard storage facility The maximum travel distance in one direction is 25 m and 45m in more than one direction (ODPM 2007, 33). b) A place of special fire hazard The maximum travel distance in one direction is 9 m and 18m in more than one direction (ODPM 2007, 33). c) The bedroom of an apartment The maximum travel distance in one direction is 9 m and 18m in more than one direction (ODPM 2007, 33). d) A lecture theatre with fixed seating in rows The maximum travel distance in one direction is 15 m and 32m in more than one direction (ODPM 2007, 33). e) Shop floor The maximum travel distance in one direction is 18 m and 45m in more than one direction (ODPM 2007, 33). f) Plant room that exits through the accommodation within a building The maximum travel distance in one direction is 9m and 35m in more than one direction (ODPM 2007, 33). 9) According to Table 3 of ADB, what is the recommended minimum number of escape routes from a storey with: a) 10 people A minimum of one escape route or exist are required (ODPM 2007, 34). b) 200 people Minimum of two escape routes or exits is required (ODPM 2007, 34). c) 450 people Minimum of two escape routes or exits is required (ODPM 2007, 34). d) 650 people Minimum of three escape routes or exits is required (ODPM 2007, 34). 10) According to Table 4 of ADB, what is the minimum exit width required to accommodate: (ODPM 2007, 36). a) 219 people Minimum width of 1050mm is required. b) 61 people Minimum width of 850mm is required. c) 10 people Minimum width of 750mm is required. d) 500 people Minimum of 5mm per person. 11) A building with four above ground floors is served by two escape stairs without lobby protection. Using Table 7 of ADB, what is the minimum width of the escape stairs if each floor accommodates: (ODPM 2007, 46). a) 75 persons Without lobby protection, only one of the two stairs can be used for simultaneous evacuation at a time. The total number of people in the four floors =75×4=300 persons Therefore, P=300, n=4, w=? P=200w+50(w-0.3) (n-1) (ODPM 2007, 47). W= (P+15n-15)/ (150+50n)=(300+60-15)/ (150+200)= 985.7mm. However, since the population is 300 the width of the stairs will be increased to 1100mm. b) 130 persons Without lobby protection, only one of the two stairs can be used for simultaneous evacuation at a time. The total number of people in the four floors =130×4=520 persons Therefore, P=520, n=4, w=? P=200w+50(w-0.3) (n-1) W= (P+15n-15)/ (150+50n)=(520+60-15)/ (150+200)= 1614.3mm However, since the population is 520 the width of the stairs will be increased to 1700mm. 12) A building with five above ground floors is served by three escape stairs with lobby protection. Using Table 7 of ADB, what is the minimum width of the escape stairs if each floor accommodates: (ODPM 2007, 46). a) 155 persons Total number of people served in five floors= 155×5=775 persons. Since the stairs have lobby protection, all the three stairs are available for simultaneous evacuation. Therefore, P=775/3=258.33, n=5. P=200w+50(w-0.3) (n-1) W= (P+15n-15)/ (150+50n)= (258.33+75)/ (150+250)= 833.325mm. Each stair should be at least 833.325mm. However, it would be raised to at least 1000mm width for each of the three stairs as per Table 7 ADB2. b) 230 persons Total number of people served in five floors= 230×5=1150 persons. Since the stairs have lobby protection, all the three stairs are available for simultaneous evacuation. Therefore, P=1150/3=383.33, n=5 P=200w+50(w-0.3) (n-1) W= (P+15n-15)/ (150+50n) = (383.33+75)/ (150+250) = 1145.825mm. Each stair should be at least 1145.825mm. However, it would be raised to at least 1200mm width for each of the three stairs as per Table 7 ADB2. 13) Assuming 100 occupants from the ground floor accommodation also exit through the ground floor of the stair enclosures for Questions 11 and 12, how wide do the final exits need to be? (i.e. a merging flow – diagram 15 and associated equation). For Question 11 a. W= {(N/2.5) + (60S)}/80 (ODPM 2007, 37). N=100 S=1.1m W= {(100/2.5) + 66}/80=1.325m The final exit should be 1.325m wide. b. W= {(N/2.5) + (60S)}/80 (ODPM 2007, 37). N=100 S=1.7m W= {(100/2.5) + 60×1.7}/80=142/80=1.775m The final exit should be 1.775m wide. For Question 12 a. W= {(N/2.5) + (60S)}/80 N=100 S=1.0m W= {(100/2.5) + 60×1.0}/80=100/80=1.25m The final exit should be 1.25m wide. b. W= {(N/2.5) + (60S)}/80 N=100 S=1.2m W= {(100/2.5) + 60×1.2}/80=112/80=1.40m The final exit should be 1.40m wide. 14) According to Table C1, what floor space factors would be appropriate in the following areas? (ODPM 2007, 135). a) An office A space factor of 6.0m2/person b) A bar A space factor of 1.0m2/person c) A shop A space factor of 2.0m2/person d) A student union (e.g. 53Degrees) A space factor of 6.0m2/person 15) For a square room, 40m by 40m, calculate the number of occupants using the floor space factors obtained in Question 14. In each case, what is the minimum number of exits required and how wide should each exit be at a minimum. 40m by 40m gives 1600m2. Therefore, For an office =1600/6=266.67 occupants, which corresponds to 266 occupants. The room will require a minimum of two exits (ODPM 2007, 34) with a minimum width of 5mm per person (ODPM 2007, 36). For a bar =1600/1= 1600 occupants. The room will require a minimum of three exits (ODPM 2007, 34) with a minimum width of 5mm per person (ODPM 2007, 36). For a shop =1600/2= 800 occupants. The room will require a minimum of three exits (ODPM 2007, 34) with a minimum width of 5mm per person (ODPM 2007, 36). For a student union =1600/6=266.67 occupants, which corresponds to 266 occupants. The room will require a minimum of two exits (ODPM 2007, 34). with a minimum width of 5mm per person (ODPM 2007, 36). 16) What is meant by the following terms: a) Life safety Life safety is the measures put in place by codes to ensure safety of persons in case of a fire break out. b) Property protection Property protection is measures put in place to ensure the safety of properties in the case of the fire break out. The measures include fire resistant elements of construction and compensation from insurers. c) Fire resistance Fire resistance is the ability of a load bearing element of a structure to resist the spread, penetration and destruction of fire. d) Cavity barrier Cavity barrier is an element of construction erected to close a concealed space to curtail the spread of fire or smoke. 17) Figure 1 and Figure 1a below represents a two storey office building, from the dimensions give an estimate for internal room sizes. With reference to Figures 1 and 1a determine: Estimates for internal room sizes Both floors have the same plan and so similar room sizes. The width of each room of the stair enclosure is estimated as 2.5m. From the left side on the upper side of the plan containing the staircases, the width of the rooms are 4m, 9m, 2m, and 5m respectively. The dimensions of the rooms give internal areas of 4×5=20m2, 9×5=45m2, 2×5=10m2, and 5×5=25m2 respectively. On the lower part of the plan where there no staircase. From the left hands-side, the rooms are 10m, 3m, 3m, 4m, and 5m wide respectively. The dimensions of the rooms give internal areas of 10×5=50m2, 3×5=15m2, 3×5=15m2, 4×5=20m2, and 5×5=25m2 respectively. a) Travel distances from each room and each floor (ODPM 2007, 33). Rooms on the ground floor Rooms adjacent to the stairs enclosures. From left to right First room: 3+2.5=5.5m to the left-side exit Second room: 4.5+4+2.5= 11m to the left-side exit Third room: 1+5+2.5= 8.5m to the right-side exit Fourth room: 4+2.5=6.5m to the right-side exit Opposite rooms. From left to right. First room: 5m to the left-side exit Second room: 2+10= 12m to the left-side exit Third room: 1+4+5= 10m to the right-side exit Fourth room: 2+5= 7m to the right-side exit Fifth room: 4m to the right-side exit Rooms on floor 2 Assumptions Persons from rooms on this floor cover approximately the same distance to the nearest stairs similar to those on the ground floor cover to the nearest exit. The total distance of each stairs is 10m and it is 1.5m from each stairs to the nearest exit giving additional distance to 11.5m for those travelling from the top floor. Rooms adjacent to the stairs enclosure. From left to right. First room: 5.5+11.5= 17m to the left-side exit Second room: 11+11.5= 22.5m to the left-side exit Third room: 8.5+11.5= 20.5m to the right-side exit Fourth room: 6.5+11.5= 18m to the right-side exit The opposite rooms. From left to right. First room: 5+11.5= 16.5m to the left-side exit Second room: 12+11.5= 23.5m to the left-side exit Third room: 10+11.5= 21.5m to the right-side exit Fourth room: 7+11.5=18.5m to the right-side exit Fifth room: 4+11.5=15.5m to the right-side exit b) Occupancy load Number people in each room are determined by using a space factor of an office, which is 6.0m2/person. The total number of per floor is given as: 20/6=3.33 approximately 3 persons 45/6= 7.5 approximately 7 persons 10/6= 1.67 approximately 1 person 25/6= 4.17 approximately 4 persons 50/6= 8.33 approximately 8 persons 15/6= 2.5 approximately 2 persons 15/6= 2.5 approximately 2 persons 20/6= 3.33 approximately 3 persons 25/6= 4.17 approximately 4 persons The total number of persons per floor= 3+7+1+4+8+2+2+3+4= 34 persons c) Purpose group An office building falls under the purpose group 3. d) Exit and final exit widths W= {(N/2.5) + (60S)}/80 (Vol 2, 37) W= {34/2.5 + 60×1.25}/80=88.6/80= 1.1075 approximately 1.108m. Hence the finale exists should be 1.108m wide. e) Stair widths and From the approximation of the internal room sizes for the staircase enclosure, stair widths is given as: 2.5m/2=1.25m wide. The size of the compartment is divided by 2 because there are a two-steps stairs in each of the stair compartments. Each stair is 1.25m wide. f) Classification of wall and ceiling linings (ODPM 2007, 63). Bibliography Babrauskas, V., 1996. Heat release rate: A brief primer. Available at: [Accessed 13 January 2015] BMTRADA, 2013. Reaction to fire testing. Available at: [Accessed 14 January 2015]. Chandrasekaran, S., 2010. Fire and explosion modeling. Available at: [Accessed 13 January 2015] CFBT-US, 2011. Gas explosions. Available at: [Accessed 14 January 2015]. England. Office of the Deputy Prime Minister(ODPM) (2007) Fire safety: Approved document B (Vol 2). London: The Stationary Office. National Institute of Standards and Technoly (NIST), 2013. Fire behavior. 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