Tactics for Achieving Fire Safety Success - Assignment Example

Combustion Student’s Name Tutor’s name Course Date Combustion Section A 1. In approximately 250 words, discuss the different extinguishing methods of water, a powder and a carbon dioxide fire extinguisher. In fighting fire, there are different fire extinguishers that can be used to smother fire and stop its spread. The choice of extinguishing method depends on the type of fuel or the cause of fire. The main three different types of extinguishers contain water, powder, and carbon dioxide. The respective extinguishing method is only used where they starve and smothers fire ultimately killing it. In other classes of fires, water can assist in the spread and growth of the fire. Water extinguishers are used in fighting class A fires. Class A fires are caused by burning carbonaceous materials such wood, papers, and textiles among others (The Fire and Safety Centre, 2014). Water cannot be used to fight fires caused by flammable fluids and electrical equipment. Powder extinguishers are used in fighting Class A fires as well. In addition, the powder is used in fighting Class B fires. Class B fires include those fires caused by flammable liquids, petroleum products, and spirits among others (The Fire and Safety Centre, 2014). Also, the powder is used in Class E fires, which are usually caused by electrical equipment and may still contain electric current (The Fire and Safety Centre, 2014). The powder forms a solid layer on the burning substances depriving fire the necessary ingredient, oxygen, to grow. Carbon dioxide extinguishers are only used to fight two classes of fires; Class B and Class E. Carbon dioxide can be used alongside powder in fighting fires from flammable fluids and those caused by electrical equipments and may still contain electric current (The Fire and Safety Centre, 2014). Carbon dioxide cuts the supply of oxygen to the burning surface by creating an inert layer on top of burning substances. Thus the fire dies out due insufficient oxygen supply. 2. In approximately 250 words explain what is meant by, and the differences between, prescriptive and performance based design. In fire safety standards, there are codes and design specification that must be met when constructing different types of buildings. Prescriptive and performance based designs are used to incorporate specific building requirements and specifications to meet the safety standards required for the structure. Prescriptive design is where specific requirements, span tables, pre-fined design options and rules are applied to develop a design that complies with the codes of required standards (Woodworks, 2014). The prescriptive design approach follows structural design standards that conform to the type of structure under construction. On the other hand, in the performance based design approach, there is not prescribed code of standards to follow when designing a building. However, the building under construction must meet some measurable and or predictable performance requirements (Woodworks, 2014). In this approach, there are no prescribed means of achieving the performance-based requirement such as energy efficiency. One design approach cannot be used to replace the other. There are differences that exist between prescriptive and performance based designs. Prescriptive codes only allow for a minimum safety factor of 10%. On the other hand, performance based designs, safety factors are evaluated case by case basis, making several assumptions due to potential uncertainties involved (Building and Construction Authority, 2013). Owing to the unpredictable nature of fire, proper use of performance based design can used as an improvement to prescriptive based codes (Alaska Housing Finance Corporation, 2011). 3. In approximately 250 words, explain the difference between complete and in-complete combustion. Combustion is the thermal reaction of oxygen with fuels to produce products. Therefore, the volume of oxygen supplied for combustion would determine the extent of reactions. When a substance is burnt, it undergoes either complete or incomplete combustion depending on the amount of oxygen available for combustion. When a substance burns, it is thermally broken down, releasing new products that vary with the fuel under consideration. Complete combustion requires a sufficient supply of oxygen to enable a full reaction of elements of the fuel (Bitesize, 2015). Complete combustion releases much safer gaseous products than those from incomplete combustion. In addition, in complete combustion, the fuel must be the limiting factor in the thermal reaction for full reaction of fuel elements. When a hydrocarbon fuel undergoes complete combustion, there are only two products are formed, namely carbon dioxide and water (Bitesize, 2015). Combustion under inadequate supply of oxygen or air leads to incomplete combustion. Therefore, incomplete combustion occurs when oxygen is the limiting factor of thermal reaction. All oxygen supplied would be exhausted before the fuel is consumed fully. Incomplete combustion of hydrocarbon produces three products, namely carbon, carbon monoxide, and water (Bitesize, 2015). The carbon is released in the form of soot. In addition, carbon monoxide released is poisonous when breathed. In conclusion, the volume of oxygen supplied for combustion would determine whether combustion is either complete or incomplete. 4. In approximately 250 words, explain the difference between premixed and diffusion flames. Flames are broadly classified as premixed and diffusion flames. The main difference between the two types of flames is the way oxygen or air is mixed during combustion. In diffusion flames, air, which is the oxidizer mixes with the flame simultaneously through diffusion as burning continues (Pitsch, 2014). In this type of flames, combustion takes place at the interface of flame and air (Pitsch, 2014a). Here the rate of reaction is controlled by the speed at which the reactants flow. Laminar diffusion flame in the common type. However, turbulent diffusion flames may arise when there is violent interruption in the air supply. A burning candle is an example of diffusion flame (Pitsch, 2014a). Its flame has different parts marked by varying colours depending on the supply of the oxidant. The outer burning zone gets sufficient air supply, so indicates clear bluish colour. The inner part/zone is starved air, so indicates yellow colour and produces soot, an indication of incomplete combustion. In premixed flames, the air (oxidant) mixed with the fuel before reaching the flames (Pitsch, 2014b). Premixed flames burn with a thin flame front with a blue colour because the fuel is sufficiently mixed with the oxidant. Complete combustion is more common in premixed flames than in diffusion flames. In premixed flames, the rate of reaction is controlled by the reaction chemistry and not at the speed at which the fuel-oxidant mixture reaches the flame (Pitsch, 2014). A Bunsen burner flame is an example of a premixed flame. It has a thin flame front and burns with clarity, showing a pronounced blue colour the base of the flame. 5. In approximately 250 words, discuss the objectives of fire safety and the five tactics available to the fire safety designers seeking to fulfill the fire safety objectives? The fire safety designers must consider the objectives of fire safety when designing a building or a structure. The fire safety objectives include safe environment, safe building, safe compartment, safe escape route and safe attack routes. Safe environment is an objective that ensures fire safety measures are taken within the environment of a structure. Safe environment would not enhance fire spread and growth in case of a fire breakout. Safe building objective ensures buildings are designed to minimize fire spread and offer safe evacuation. Safe building ensures everyone remains safe even during a fire. Safe compartment would minimize compartmental fires from spreading to the hallway or other rooms. Compartments are constructed to confine the fire within department. Safe escape route is an objective that ensures there are well-outlined fire escape routes. These escape routes must be resistant to smoke and fire spread to ensure safe evacuation of persons in a building. Safe attack routes are an objective that ensures fire fighters would have adequate space between buildings to allow access of firefighting equipment to the buildings. There are five tactics the fire-safety designers can use to achieve fire safety objectives. They include information, insight, innovation, integration, and involvements (Fire Engineering, 1999). Under information, understanding the fire risks through past incidents would lead to a conclusive design. Insight enables fire safety designers to forge new ideas by analyzing previous occurrences. Innovation; the designer must be innovative to use the information and insight developed to achieve the objectives of fire safety. The innovative ideas must be integrated in the design codes and specifications to the objectives. Finally, everyone should be involved in the design, development and implementation of the design. Section B 1. Convert the following temperatures into Kelvin: a) 12°C b) -177°C c) 1233°C d) 392°C 2. How many moles of carbon are in 245.0g? The formula for calculating moles is given as; Molecular mass of carborn (C)=12g 3. Balance the following equations: a) Ca(AlO2)2 + HCl → AlCl3 + CaCl2 + H2O Ca(AlO2)2 + 8HCl → 2AlCl3 + CaCl2 + 4H2O b) Fe + O2 + H2O → Fe(OH)2­ 2Fe + O2 + 2H2O → 2Fe(OH)2­ c) MgNH4PO4→ Mg2P2O7 + NH3 + H2O 2MgNH4PO4→ Mg2P2O7 + 2NH3 + H2O d) AlCl3 + Ca3N2 → AlN + CaCl2 2AlCl3 + Ca3N2 → 2AlN + 3CaCl2 e) C15H26 + O2→ CO2 + H2O 2C15H26 +43O2→ 30CO2 +26 H2O 4. Ammonia and oxygen react to form nitrogen and water: 4NH3 + 3O2 → 2N2 + 6H2O a) How many grams of O2 are needed to react with 6.0 moles of NH3? From the mole ratio in the equation, 4 moles of NH3 needs 3 moles of oxygen. Therefore, 6 moles of ammonia would need 4.5moles of oxygen =4.5*32=144g of oxygen b) How many grams of N2 can be produced when 5.45g of O2 react? 5.45g gives. From the equation, 3 moles of oxygen reacts to produce 2 moles of nitrogen. Therefore, 0.17 moles of oxygen reacts with ammonia to produce c) How many grams of water can be formed from the reaction of 43g of NH3? Molecular mass of NH3 is 17g 43g gives 43/17=2.529 moles From the equation, 4 moles of NH3 react to form 6 moles of water. Therefore, 2.529 moles of NH3 react to produce 5. How many joules of heat are needed to raise the temperature of 43.0g of aluminium from 22°C to 55°C, if the specific heat of aluminium is 0.90J/g°C? (CITE) Where Q=joules of heat, m=mass of the material, , c=specific heat 6. Using the Ideal Gas Law solve the following problems: (use 0.08206 L atm mol¯1 K¯1or 8.314kPaL/molK for the gas constant). a) If 4.7 moles of propane are at 28ºC and under 154.2kPa of pressure, what volume does the sample occupy? The ideal gas law formula is Where P=pressure, V=volume, n=moles, R=the gas constant, T=temperature b) Determine the volume occupied by 3.34g of carbon dioxide gas at STP. At STP, T=0oC ant P=1atm 3.34g of carbon dioxide=3.32/44=0.0755mole c) A sample of argon gas at STP occupies 46.2L. Determine the number of moles of argon and the mass in the sample. d) At what temperature will 0.654 moles of neon gas occupy 12.30L at 1.95 atmospheres? e) A 30.6g sample of gas occupies 22.414L at STP. What is the molecular weight of this gas? First, the number of moles of the gas is determined from ideal gas equation, 7. A sample of carbon monoxide at 57ºC and under 0.67atm of pressure takes up 85.3L of space. What mass of carbon monoxide is present? First, the number of moles is determined 8. A pan 200mm diameter pan is placed on a stove to boil some water (see figure 1 page 4). The thickness of the bottom of the pan is 7.5mm and the inner surface temperature of the bottom of the pan is 150°C. Determine the outer surface temperature of the pan if the pan was a) Aluminium, and b) Copper. Assume one-dimensional, steady state conduction through the bottom of the pan. A steady rate of heat transfer from the stove to boil water in the pan is given by Where, a) If the pan is made of aluminium The formula above, Therefore, b) If the pan is made of copper The difference from part (a) is the k value, which vary with the material. References Alaska Housing Finance Corporation, 2011.Comparative analysis of prescriptive, performance-based, and outcome-based energy code systems. Available at: [Accessed 28 January 2016] Bitesize, 2016. Products and effects of combustion. BBC. Available at: [Accessed 29 January 2016] Building and Construction Authority, 2013. Performance based codes. Available at: [Accessed 27 January 2016] Fire Engineering, 1999. Five tactics for achieving fire safety success. Available at: [Accessed 29 January 2016] Pitsch, H., 2014a. Fundamental and laminar flames. Available at: [Accessed 30 January 2016] Pitsch, H., 2014b. Laminar premixed flames: Kinematics and burning velocity. Available at: [Accessed 30 January 2016] The Fire and Safety Centre, 2014. Fire extinguisher user guide. Available at: [Accessed 25 January 2016] Woodworks, 2014. Prescriptive or engineering design. Available at: [Accessed 25 January 2016] Read More