Engineering Design Practice: Fire Resistance Testing - Assignment Example

ENGINEERING DESIGN PRACTICE By Student’s name Course code and name Professor’s name University name City, State Date of submission PART A – Answer all 5 questions – total marks for this section is 50%. Include appropriate references. 1. What is fire resistance testing? (10 marks) Solution Fire resistant testing is a mode rating fire resistance of structural materials or assemblies through measurement of customary units as may be desired by the existing standards. Fire resistance testing aims at establishing the ability of the system or an individual material’s ability to resist or prevent fire passage from one distinct section to the other. Basically, the test classifications that usually govern this important issue include; United Kingdom Building Regulations, International fire test standards and European Classification. These may also differ based on the certification schemes, approval requirements of various approval bodies, insurers and underwriters (Gross, 2007). It is therefore important to test all the fire parameters in order to secure the safety of the occupants and property. Architectures and design engineers are expected to ensure that the elements of upcoming structures are redundant against any mode of collapse against eventualities of fires for a given period of time. This is especially to allow evacuation exercises and also to avoid deaths or losses of property. The requirements of British standard 476 indicate all the appropriate measures to be carried out when engaging any form of resistance testing with revisions such as BS 476-12:1991 highlighting methods of testing for ignitability due to thermal resistance, BS 476-10:2009 breaking down how material should be selected for various purposes with respect to fire resistance and so many other clauses that are worth determining the fire resistance testing parameters for safe occupancy (Safelincs Ltd., 2011). 2. What is reaction to fire testing? (10 marks) Solution Usually fire resistance testing involves physical measurement of parameters involved in ensuring that a given material can endure fire for a certain period of time to ensure that occupants are granted escape. Reaction by a material to fire involves the measurement of how a material or system as a whole will contribute to development and spread of fire especially during the early stages. The reaction to fire is measurable and is critically measured using parameters such as material flammability, surface spread of flame, Single-flame source test (SFI), single burning item (SBI) and ignitability. The reaction to fire is treated as an important parameter towards the achievement of safety since the factors contributing towards fire spread are affiliated to the ease at which ignitability and energy or flame spread across a system. Reaction to fire is required as a compliance criteria for approved document B for building regulations within the UK. The European classification for fires classifies reaction for fire as shown in the two tables below which are also embraced in the UK (BM TRADA, 2012). Table 2.1: Requirements for building materials as seen in approved document B (BM TRADA, 2012). Table 2.2: Classification in accordance to fire reaction (BM TRADA, 2012). 3. Discuss the term “flammability limits”. Discuss the effects of temperature on flammability limits. Include diagrams. (10 marks) Solution Flammability limits is defined as the range of compositions for a given pressure and temperature within which explosion is probable whenever an external mode of ignition is introduced. These are usually given in terms of fuel percentage or ratio at a given pressure and temperature. Flammability limits have been found to be higher at the source of the ignition stimulus as compared to leaner mixtures. This also depends on the environmental characteristics such as temperature and pressure ( Fauske, 2013). The flammable mixtures are characterised as of lower flammability limits and upper flammability limits with the richest flammable mixture being on the upper limit. The growing concerns of explosions resulting from storing hazardous chemicals within areas of occupancy leading to research on flammability limits. The manufacturing industries are therefore required to invest in MSDS declarations and investigations to establish material flammability with respect to various determinants or parameters. Temperature for example has become an extremely studied parameter owing to the fact that it is the main determinant when it comes to the clustering of flammability limits. The graph below indicates the flammability limits with respect to temperature ( Fauske, 2013). Figure 3.1: Effects of temperature on combustible mixtures (Crowl, 2003). 4. Discuss heat release rate in relation to fire hazards. Solution Heat release rates are very important in the study of fire spread in both occupancy areas and industrial setups. Hazards in fires are specifically related explosions and damages that are directly dependent on the heat release rates. Typical fires are considered to have impacts in terms of occupant death, injuries and not necessarily resulting dangers such as fire spreads, growth and immediate contact. The phenomenon that is used to classify the effects of fire are; ignition, flame spread, heat release and release rates for smoke and toxic gases. Heat release rate is closely related to loss of mass and consequent introduction of alien toxic gases that are responsible for bodily harm and corrosive reactions (Babrauskas & Peacock, 1992). Figure 4.1: A graph of heat release rate (HRR) with respect to time (CFBT-US LLC, 2009). An analysis carried out by Babrauskas and Peacock (1992) indicate that the temperatures and carbondioxide levels increase with heat release rate. The carbondioxide production represents the type of curves that the other toxic gases may take in any given instance.Heat release rate has been found to have a great impact than the initability of a material as earlier scholars might have though. Toxicity is related to the heat release rate as indicated from the experiments carried out by Babrauskas and Peacock (1992). Tenability has also been investigated with respect to space and heat release rates only to establish that the situations get worse in case of space limits. Thus space also sets in as a parameter when toxicity is involved with repsect to heat release rate. A simulation carried out over 600 seconds to demonstrated the importance of this parameter in fire investigation indicated that time to death decreased by almost half as compared to a case base. Figure 4.2: Comparative analysis of heat release rate and CO2 concentration (Babrauskas & Peacock, 1992). 5. Discuss the factors which will influence the fire development and the rate of fire growth within a compartment. (10 marks) Solution A lot of experiments have been set up over time to establish the factors that are responsible for development of fires in built environments. Compartment fires are described in terms of the heat release rates, burning regimes and the various stages of fire as shown in figure 4.1 above. Some of the factors that have been identified to influence fire and the rate at which it grows include; fire load, size, the compartmentation type, ventilation profile and thermal properties of the construction materials. The fire rate is affected by the mass and the burning characteristic of a given fuel which also doubles as a construction material. The size of the compartmentation on the other side effects fire in an inverse manner in that the smaller the compartment the quicker the fire spread. This is however different in highly compartmented buildings as the fire seems to slow in this case. Large compartments definitely contain more air thus may contain a massive supply of fuel load to burn. In another instance, the thermal properties of a given construction material (fuel) affects the fire spread rate in that materials with higher thermal properties call for better insulation in order to avoid such rampant catastrophic poses. A Styrofoam compartmentation is therefore likely to bring about more fire problems than may be caused by brick walls. Lastly, the ventilation profile is affected by such openings as created by civil occupants, unplanned ventilations and tactical approaches to set the fires off. The fire profile shall affect the fire spread due to oxygen supply at the early stage of fire development thus modifications should only be made under the advice of design experts (Shaw, 2010). PART B – Answer ALL questions – total marks for this section is 50%. Use Approved Document B to answer the following questions. Include appropriate references. 1) What are the 5 functional requirements of Approved Document B? (5 marks) Solution The following are the five functional requirements of document B: i. Means of warning and escape – This is to make sure that a satisfactory means of warning occupants is offered by the designers and builders. ii. Internal fire spread (linings) – this ensures that fire spread in internal linings is actually inhibited. iii. Internal fire spread (structure) – Ensures that the building stability is maintained or at least sustained in event of a fire. iv. External fire spread – ensures enough resistance to external walls in order to avoid the spread of fire from one building to the other. v. Access and facilities for the fire service – ensures that accesses for fire appliance to buildings including the provision of facilities to fight fire is made mandatory in order to reduce the eventualities of fire. 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. (4 marks) Solution Means of escape may be defined as a physical facility that enables occupants to be alerted in case of a fire and therefore is strategically positioned to offer them escape to a safe area usually known as fire assembly point. There are usually several alternatives that may be availed in a building such as protected stairway which should also be offered a reasonably safe distance to the nearest point of exit. These routes are also suggested to be well lit in order to offer safe exit to building occupants. Exits should be well signed as to give a direct notice to occupants once they reach there. Finally it is appropriate to for an escape route to offer a restriction to smoke and fire. 3) What is the maximum recommended compartment size for each of the following cases: a) A single storey shop with sprinkler protection b) A single storey industrial unit (1 mark) Solution a. No limit. b. No limit. 4) What is the maximum size of an opening (unprotected area) that can be discounted when considering space separation between buildings? (1 mark) Solution 1000mm 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 b) A four storey assembly building with a top storey of 1400m2 located 10m above fire service vehicle access level. (1 mark) Solution a. In accordance to provision 18.2 of document B2000, a fire fighting lifting and shaft are required. b. Only firefighting shafts shall be required in accordance to section 18.3. 6) What is the minimum recommended fire resistance periods for the following structures: a) A 35m high sprinkler protected residential building b) A four storey shop with sprinkler protection (1 mark) Solution a. 30 minutes b. One hour. 7) What purpose groups would be appropriate for the following premises? a) A students union building (e.g. 53°) b) A department store c) A factory d) A swimming pool building (2 marks) Solution a. Purpose group 3 b. Purpose group 4 c. Purpose group 6 d. Purpose group 5 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 b) A place of special fire hazard c) The bedroom of an apartment d) A lecture theatre with fixed seating in rows e) Shop floor f) Plant room that exits through the accommodation within a building Solution a. 9m for one direction and 18m for more than one direction b. 6m for one direction and 12m for more than one direction. c. 9m for one direction and 18m for more than one direction. d. 15m for 1 direction and 32m in case of more than one direction. e. 18m for 1 direction and 45m in case of more than one direction. f. 9m for single direction and 18m in case of more than one direction. 9) According to Table 3 of ADB, what is the recommended minimum number of escape routes from a storey with: a) 10 people b) 200 people c) 450 people d) 650 people Solution a. 1 b. 2 c. 2 d. 3 10) According to Table 4 of ADB, what is the minimum exit width required to accommodate: a) 219 people b) 61 people c) 10 people d) 500 people Solution a. 1050mm b. 850mm c. 750mm d. 2500mm based on a maximum 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: a) 75 persons b) 130 persons (2 marks) Solution a. 1000mm b. 1100mm 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: a) 155 persons b) 230 persons (2 marks) Solution a. 1000mm b. 1000mm 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) (4 marks) Solution 11 a. Since the flow will serve 100 more people, then the final width will be 1700mm. 11 b. 1800mm. 12 a. The exit serves a maximum of 875 people with each requiring 5mm thereby totalling to 4375mm as the final figure. 12 b. 230 persons served by each floor totals to a maximum of 1250 people. Therefore the total width required for the exit is 6250mm. 14) According to Table 1, what floor space factors would be appropriate in the following areas? a) An office b) A bar c) A shop d) A students union (e.g. 53Degrees) (2 marks) Solution a. 6.0m2 per person b. 1.0m2 per person c. 2.0m2 per person d. 1.0m2 per 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 as a minimum. (4 marks) As per table 4 and 5 Scenario No. of occupants Minimum no. of exits Size per exit (5mm per person) 14 a 1600/6 3 750mm 14 b 1600/1 3 2666mm 14 c 1600/2 3 1333mm 14 d 1600/1 3 2666mm 16) What is meant by the following terms: a) Life safety b) Property protection c) Fire resistance d) Cavity barrier (4 marks) Solution a. Life safety is the ability of an establishment to deliver occupants to safe egress without stretching the existing resources in case of an eventuality as per set rules and statutory guidelines. b. Property including the building itself should be protected in case of a fire and therefore this is measurable in that it is the ability to prevent losses to a tune of a certain amount of money. c. This is the ability of a material to withstand a basic fires test for a specified period of time. d. A cavity barrier refers to a construction apart from a smoke curtain that is provided close a concealed area in order to provide protection in case of a fire – restricts movement of smoke in case of a fire. 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: a) Travel distances from each room and each floor, b) Occupancy load c) Purpose group d) Exit and final exit widths e) Stair widths and f) Classification of wall and ceiling linings (10 marks) Solution a. Upon analysis, the safe distances provided for each room do not exceed the recommended Read More

The reaction to fire is measurable and is critically measured using parameters such as material flammability, surface spread of flame, Single-flame source test (SFI), single burning item (SBI) and ignitability. The reaction to fire is treated as an important parameter towards the achievement of safety since the factors contributing towards fire spread are affiliated to the ease at which ignitability and energy or flame spread across a system. Reaction to fire is required as a compliance criteria for approved document B for building regulations within the UK.

The European classification for fires classifies reaction for fire as shown in the two tables below which are also embraced in the UK (BM TRADA, 2012). Table 2.1: Requirements for building materials as seen in approved document B (BM TRADA, 2012). Table 2.2: Classification in accordance to fire reaction (BM TRADA, 2012). 3. Discuss the term “flammability limits”. Discuss the effects of temperature on flammability limits. Include diagrams. (10 marks) Solution Flammability limits is defined as the range of compositions for a given pressure and temperature within which explosion is probable whenever an external mode of ignition is introduced.

These are usually given in terms of fuel percentage or ratio at a given pressure and temperature. Flammability limits have been found to be higher at the source of the ignition stimulus as compared to leaner mixtures. This also depends on the environmental characteristics such as temperature and pressure ( Fauske, 2013). The flammable mixtures are characterised as of lower flammability limits and upper flammability limits with the richest flammable mixture being on the upper limit. The growing concerns of explosions resulting from storing hazardous chemicals within areas of occupancy leading to research on flammability limits.

The manufacturing industries are therefore required to invest in MSDS declarations and investigations to establish material flammability with respect to various determinants or parameters. Temperature for example has become an extremely studied parameter owing to the fact that it is the main determinant when it comes to the clustering of flammability limits. The graph below indicates the flammability limits with respect to temperature ( Fauske, 2013). Figure 3.1: Effects of temperature on combustible mixtures (Crowl, 2003). 4. Discuss heat release rate in relation to fire hazards.

Solution Heat release rates are very important in the study of fire spread in both occupancy areas and industrial setups. Hazards in fires are specifically related explosions and damages that are directly dependent on the heat release rates. Typical fires are considered to have impacts in terms of occupant death, injuries and not necessarily resulting dangers such as fire spreads, growth and immediate contact. The phenomenon that is used to classify the effects of fire are; ignition, flame spread, heat release and release rates for smoke and toxic gases.

Heat release rate is closely related to loss of mass and consequent introduction of alien toxic gases that are responsible for bodily harm and corrosive reactions (Babrauskas & Peacock, 1992). Figure 4.1: A graph of heat release rate (HRR) with respect to time (CFBT-US LLC, 2009). An analysis carried out by Babrauskas and Peacock (1992) indicate that the temperatures and carbondioxide levels increase with heat release rate. The carbondioxide production represents the type of curves that the other toxic gases may take in any given instance.

Heat release rate has been found to have a great impact than the initability of a material as earlier scholars might have though. Toxicity is related to the heat release rate as indicated from the experiments carried out by Babrauskas and Peacock (1992). Tenability has also been investigated with respect to space and heat release rates only to establish that the situations get worse in case of space limits. Thus space also sets in as a parameter when toxicity is involved with repsect to heat release rate.

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