Engineering Design - Coursework Example

FIRE DESIGN ASSIGNMENT [NAME] [INSTITUTIONAL AFFILIATION] [DATE] Table of Contents PART A 3 What is Fire Resistance Testing? 3 What is Reaction to Fire Testing? 3 What is Flammability Limits? 4 Heat release rate in relation to fire hazards 4 Fire Development & Rate of Fire Growth in a building Compartment 6 PART B 9 References 20 PART A What is Fire Resistance Testing? Fire testing is a phenomenon that is used by most engineers in determining the rate at which a building or a structure is capable of withstanding or resisting a particular temperature at a particular time and at a given environment when the same structure is fully exposed to a particular pressure and the structure still withstands its functions. Various components of a structure are identifies for the testing purposes. The components may include such parts as the walls and the ceilings. The section being tested is placed in a heating chamber like the oven and temperature indicators mounted on it which further records the temperatures. It is noted that the sections that are protected for example those where engineering regulations have been followed as required, do not collapse while the unprotected ones eventually collapse (Brannigan & Corbett 2007). What is Reaction to Fire Testing? Reaction to fire testing is the rate by which a component or a section or a compartment contributes to the degree of fire development and the rate by which it spreads within an enclosed region or within a compartment. This is contributed by various factors that exist within the compartment which may include factors such as ventilation, amount of oxygen supply into the compartment and the geometry of the section. Reaction to fire testing is a factor of much concern amongst individuals especially the way people react to the fire outbreak and spread which is particularly noted during initial fire outbreak. Reactions depend on whether the outbreak is within a building compartment or whether it is outside the building chamber. For better rescue of individuals, the government regulations with respect to the building designs must be adhered to and such government regulations entail things like lifts and stair cases within a building chamber (Reese 2012).  What is Flammability Limits? Flammability limits may be looked at as the limits or the ranges in pressures and temperatures determined by their ingredients or compositions which may contribute to various explosions when external factors and forces are brought to effect. The degree of the fuel concentration in various temperatures and various pressures and the strength of ignition also contribute a lot to the flammability limits, for example, the flammability limit is higher with increase in the strength of ignition and decreases with the decrease in the ignition strength. Flammability limits may also be affected by the availability of free oxygen in the surrounding area. It is higher in oxygenated area as compares to an area with less oxygen supply. Increase in pressure results into an increase in pressure, which is also another major contributing factor that influences the flammability limit. As temperature increases, the flammability limit also increases (Mannan 2014). Fire safety of a design may be studied using such designs like deterministic analysis where several factors of fire design are analyzed then various descriptions follow such as the rate at which heat is released and the availability of the toxic species that exist in the mixture. The best fire design must therefore be selected with respect to the building and engineering designs to ensure maximum safety within building compartments are met for safety purposes. Heat release rate in relation to fire hazards Heat release rate is the “power” of fire or can be referred to as the “power” of fire. Its relation to time characterizes the development of fire. Therefore, the determination of heat release rate or the burning rate is necessary while carrying out fire hazard analysis. A plot of heat release rate against time is regarded as design curve for fire and is illustrated in the fire bellow. Figure 1: Fire Design Curve Since heat release rate is not a basic characteristic of any fuel, it cannot be computed out of a material’s basic properties. Under usual circumstances, it is determined by testing. Heat release rate can be assessed by measuring the burning rate, also known as mass loss rate. This is achieved by finding the weight of fuel package while it burns. This also requires the knowledge of mass loss rate for effective combustion of heat. The equation that follows is used in the calculation of heat release rate. Where; heat release rate in kW mass flow rate in Kg/second change in effect combustion heat in Kj/Kg Fire Development & Rate of Fire Growth in a building Compartment 1. The Ventilation Factor and oxygen supply Ventilation factors and the amount of oxygen supply within a building is majorly contributed by the amount of available space within a building compartment. The larger the size of the compartment the higher the amount of oxygen present and the well-ventilated compartment results into maximum amount of oxygen supply into the building chambers. When fire within a compartment burns in a well ventilated place, the rate at which it spreads is higher and the rate of fire spread is slower in a very poorly ventilated compartment. The less rate of spread is contributed due to the less amount of oxygen supply into the compartment. When any part of the compartment the door, either 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 (Frequent 2010). 2. The Surface geometry of a compartment Geometry in a building compartment refers to the angle of inclination in which various compartment sections are designed with respect to each other. Some sections may be inclined at right angle to one another while some are at lesser angles of acute. The lesser the geometry, the faster the spread as materials are closer to each other making the spread rate to be higher for example, the flame spreads very fast with decrease in the angle. When the geometry is wider, the materials are far apart and the rate at which the spread takes place becomes slower. 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. 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. In addition, 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 (Mullinger & Jenkins 2014).  3. The surrounding environment of a compartment An environment conducive for the spread to take place must prevail within the compartment and outside the compartment. This is contributed by such factors as temperature gradient, pressure differences, availability of oxygen and humidity. When the humidity level is so high, the amount of oxygen available to enhance combustion becomes minimal. The lesser the oxygen, the slower the rate of spread as combustion will never be fully supported. Therefore, the higher the humidity, the lesser the rate at which fire spreads and the lesser the humidity of the surrounding environment, the faster the rate at which fire will spread. 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. Combustible gases present in the environment also determine the rate at which the fire spreads within a building compartment. With the availability of the combustible gases like the oxygen, the burning rate of a material within a compartment 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 (Rau 2010).  4. Fuel supply For burning to take place, there must be availability of such factors like the fuels, which enhance the combustion process. The fuel must be a combustible one. When higher amounts of combustible fuels are supplied into a chamber, they are broken down into burning components, which supports further burning of the materials within a compartment. The amount of fuel being supplied into a compartment really determines the rate at which fire spreads within the compartment. The higher the amount supplied, the faster the rate of fire spread and the lesser the amount being supplied, the slower the rate at which the fire spreads within a 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. 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 in order to identify the ones that are fully flammable and those that are less flammable. This makes it possible to know which materials to store in particular places within a compartment to enhance maximum security within a building chambers. 5. The Boil over of some materials like water There are some materials that do not really support combustion but when they are split into various components that constitute them then they support further burning of various materials. The boil over is therefore 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 various components. One of the components being the oxygen. that supports combustion. The oxygen part then promotes further burning and the spread of the fire within a compartment is seen to be much faster and is sustained for a longer period of time. The increase of the area fuel spray creates a rapid increase in the fire spread within any chamber in a compartment. 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 PART B (The questions have been answered using the document provided. Approved Document B) 1. State the five Functional Requirements of Approved Document B The five functional requirements of the given document D include the following a. The both the warning means the and escape means b. How the internal linings contribute to the spread of fire. c. How the nature of the building contributes to the spread of fire. d. How fire spreads in an external environment e. The facilities that are used for the purpose of fire services 2. What is the Means of Escape from Fire? Means of escape from fire may be defined as a way in which people can vacate an area that has an outbreak of fire within a compartment. This is facilitated by various devices that are set up in a structure which are required by the building regulations. For example, stairway that is attached to a building or any structure that helps during emergencies when there is an outbreak of fire. What are the main Requirements of Safe Means of Escape from a Building in case of fire outbreak? Various precautions can be put in place to ensure there is safe ways of escape within a compartment in case there is fire outbreak within a compartment.Alternative means of escape in case of fire are set in place which includes such measures like staircases and the lifts where necessary. The escape should be direct to the place of safety and if not possible, the escape route should allow access to an area of relative safety. A stairway that is protected and which lies on an exit route and travel distance should be reasonable. Some conditions require the existence of a single escape direction for provision of reasonable safety. 3. What is the Maximum Recommended Size of Compartments? (a) A single storey shop with sprinkler protection When considering a storey shop with a sprinkler protection, there should be no limit as to floor height of the top storey for the building above the ground level. The floor area has not limit and can be designed depending on the preference of the designer. (b) A single storey industrial unit When designing a single storey industrial unit that is sprinkled or not sprinkled, there is a maximum limit that the designer or an engineer must consider to ensure security within such premises. The maximum height should not be more than 18m while there is no limit in terms of floor area of such a premise. 4. What is the maximum size of an opening (unprotected area) that can be discounted when considering space separation between buildings? We must first consider the distance from where the total intensity of thermal energy is reached. The maximum distance should therefore, be a distance not less than ½ the distance at which total intensity of thermal radiation is received. 5. State whether a fire-fighting shaft is recommended in each of the following and whether or not a fire fighting lift is required: I. An office building with a top occupied floor of 250m2 located at 19m above fire service vehicle access level Fire fighting lift and shaft are design devices that are used in a building to facilitate safety within a building compartment. For a structure with an area of 250m2, the two facilities are very much recommended. Further, a fire fighting lift should be used as a means of escape & to help fire fighters access the facility and to easily rescue the victims. II. A four storey assembly building with a top storey of 1400m2 located 10m above fire service vehicle access level For the assembly buildings with less heights of less than 10 m height, the fire fighting shaft and lifts may not be required but for higher heights of above 10m, it may be requires facilitating easy access to the higher components of the building during cases of emergency. 6. What are the minimum recommended fire resistance periods for the following structures? a) sprinkler protected residential building A 35m high in height The fire resistance period for such a height is estimated at 30 minutes b) A four storey shop with sprinkler protection The fire resistance period for such a height is estimated to be 60 minutes 7. The purpose groups that would be appropriate for the following premises a. Considering students union building which is under group 2(a) residential or institutional purpose group b. The departmental store is classified under group 7 (a) storage & other non-residential categories c. A factory may be categorized under the industrial purpose category 5 d. A swimming pool building is categorized under the purpose class 5 for assembly & recreation purposes 8. According to Table 2 of Approved Document B, identify the recommended travel distance limitations (single direction & more than one direction) for the following parameters A normal hazard storage facility The travel distance is estimated to be at 25m for one direction and 45m for distances that are more than one travel direction A place of special fire hazard The travel distance is estimated to be at 9m for one direction & 18 m for distances that are more than one travel direction The bedroom of an apartment The travel distance is estimated to be at 9m for one direction & 18 m travel direction for those distances that are more than one A lecture theatre with fixed seating in rows The travel distance is estimated to be at 15m for one direction & estimated to be 32 m for distances that are more than one travel direction Shop floor The travel distance is estimated to be at 18 m for one direction and estimated to be 45 m for the travel direction that is more than one Plant room that exits through the accommodation within a building The travel distance is estimated to be at 9m for one direction and estimated to be 35 m for the travel direction that is more than one 9. According to Table 3 of Approved Document B, identify the recommended minimum number of escape routes from a storey with. For 10 people, it is estimated to have 1 escape route For 200 people, it is estimated to have 2 escape routes For 450 people, it is estimated to have 2 escape routes For 650 people, it is estimated to have 3 escape routes 10. According to Table 4 of Approved Document B, identify the minimum exit width required to accommodate: For 219 people The estimated Minimum width should be 1050 mm during the design For 61 people The estimated Minimum width should be 850 mm For 10 people The estimated Minimum width should be 750 mm. this can still be can reduced to an estimated figure of 1050mm in the case of gangways that lie between fixed storage rackings. For 500 people The estimated Minimum width should be 5 mm per person 11. A building with four above ground floors is served by two escape stairs without lobby protection. Using Table 7 of Approved Document B, identify the minimum width of the escape stairs if each floor accommodates the under mentioned number of persons 75 individuals The estimated Minimum width should be 1000 mm 130 individuals The estimated Minimum width should be 1200 mm 12. A building with five above ground floors is served by three escape stairs with lobby protection. Using Table 7 of Approved Document B, what is the minimum width of the escape stairs if each floor accommodates: 155 people The estimated Minimum width should be 1500 mm 230 people The estimated Minimum width should be 1800 mm 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? (that is, a merging flow – diagram 15 and associated equation). The estimated number of occupants that exist from group floor is said to be 100, the final exit width will have (27 x 2) plus the estimated number of occupants which in this case is 100. This translates to a total figure of 154 persons. Therefore, the final exit, according to Approved Document B estimates to a total distance of 1050 mm 14. According to Table C1, identify the floor space factors that would be appropriate in the following areas An office premise The estimated floor space factor should be 6 m2 for every person A bar premise The estimated floor space factor should be 0.3 m2 for every person A shop premise The estimated floor space factor should be 2.0 m2 for every person A students union premise The estimated floor space factor should be 1.0 m2 for every person 15. For a square room, 40m by 40m, calculate the number of occupants using the floor space factors obtained in Question 14 above. In each case identify the minimum number of exits required and the minimum width of each exit. Areas is calculated as shown alongside 40 x 40 which translates to 1600m2 The number of occupants will be as follows, depending on the floor space factor: An office premise = 1600/ 6 m2/ person that translates to 267 persons A bar premise = 1600/ 0.3 m2/ person that translates to 5333 persons A shop premise = 1600/ 2.0 m2/ person that translates to 800 persons A students union premise = 1600/ 1.0 m2/ person that translates to 1600 persons 16. Define the following phrases: What is Life safety? Life safety may be defined as the satisfactory measures that are employed for limiting the dangers that can happen to an individual due to such factors as smoke, heat, or firefighting waters. What is Property protection? Property protection refers to satisfactory standards that are put in place to limit the damages to building components, building fabric, or business operation in the short time due to such factors as smoke, heat and the fire fighting water. What is Fire resistance? Fire resistance refers to the measure that are put in place in the design process by engineers or designers to help the components withstand fire effects such as resisting collapse, fire penetration to the other components, and excessive heat transfer to other various compartments within a building. What is Cavity barrier? These are construction elements meant for restricting the spread of flames and smoke through the cavities. They assist in reducing the chances of unseen fire spread. 17. Figure 1 and Figure 1a below represents a two-storey office building, from the given dimensions, give an estimate for internal room sizes. With reference to Figures 1 and 1a determine: a. What are the Travel distances from each room and each floor? Ground floor, 1st floor, and 2nd floor 1st rooms from exit equals to 5 m + 5 m that translates to 10 m 2nd rooms from exit equals to 10 m + 5 m that translates to 15 m 3rd rooms from exit equals to 15 m + 5 m that translates to 20m 4th rooms from exit equals to 20m + 5 m that translates to 25 m 5th rooms from exit equals to 25 m + 5 that translates to 30 m b. Occupancy load The arrangement of this layout indicates business occupancy where the occupant load is generally 1 person per 100 square feet of the total floor area. c. Purpose group The layout stands for purpose group 4, shop, and commercial. d. Exit and final exit widths Total floor area equals to 25 x 10 that translates to 250 m2 Occupancy load equals to 1 person / 100 square feet that translates to 1 person/ 9.2m2 Number of occupants per floor equals to 250/9.2 that translates to 27 individuals For all the floors equals to 27 x 3 that translates to 81 individuals Therefore, exit width = 1000 mm and final exit width is 1800 mm e. Stair widths equals to 1000 mm 18. How are walls and ceiling linings classified? Majorly the ceiling Linings are classified according to location. The area is of major concern when doing such classifications of wall linings and the ceiling linings. For example, small rooms with small areas that are less than 4 m2, domestic garages with areas that are less than 40m2, other rooms and the spaces for circulation within the dwelling houses (Great Britain 2007). References Top of Form BRANNIGAN, F. L., & CORBETT, G. P. (2007). Brannigan's building construction for the fire service. Sudbury, MA, National Fire Protection Association. FRIQUIN, K. L. (2011). Material properties and external factors influencing the charring rate of solid wood and glue-laminated timber. Fire and Materials. 35, 303-327. GREAT BRITAIN. (2007). Approved document B. London, NBS/RIBA Publishing. MANNAN, S. (2014). Lees' process safety essentials: hazard identification, assessment and control. MULLINGER, P., & JENKINS, B. (2014). Industrial and process furnaces: principles, design and operation. Oxford, Butterworth-heinemann. RAU, D. M. (2010). Fire safety. New York, Marshall Cavendish Benchmark. REESE, C. D. (2012). Accident/incident prevention techniques. Boca Raton, Taylor & Francis. Read More