Combustion and Fire - Assignment Example

Fire and combustion assignment Section one: 1. Effects of sprinklers on society Since humans discovered how to extinguish fire, fire suppression methods have constantly evolved. At firsts humans formed bucket brigades to shuttle water from a water source to a fire. Today numerous fire suppression methods are used to provide fire protection and the future holds even more fire suppression developments and employment. The development of fire protection measures is constantly challenged by architects unique features and structures. As a result, fire protection engineers use performance based designs. In this case, the engineer has to be aware of a fire scenario and an ability to predict fire behavior with practical engineering tools. Sprinkler system design criteria are the long standing and well established method for life safety provision and property protection. The sprinkler has to work by detecting spread combustion gases such that the ability to predict the impact of a sprinkler can be made in times of fire. The design of the sprinkler system design requirements differ based on the type of occupancy being protected, commodity type and storage configuration, the type of sprinklers like standard spray sprinklers, control mode specific application sprinklers, and early suppression fast response sprinklers and sprinkler installation like in the ceiling level or in racks (Dyer 2008). Apart from safety and property protection, sprinklers are used to environmental sustainability through the reduction of the amount of water needed to extinguish fire. According to Business sprinkler alliance (2013), the development of a sustainable society in the UK is challenged by global warming and climate change. In addition, fire impacts the surrounding environment through emission of gases and particulates to the atmosphere, distribution of atmospheric emissions, deposition of atmospheric emissions and contamination of soil and water aquifers. Through the installation of fire sprinklers, the release of greenhouse gases is reduced by about 98% while the release of soot is reduced by about 99.99% as indicated in a research commissioned by FM Global. Business sprinkler alliance (2013) attributes the efficiency of sprinklers on environmental sustainability to the amount of water discharged and the quick detection of fire and initiation of fire suppression measures. Basically, a sprinkler’s head discharges 40-45 liters of water every minute. This is far too less but effective compare 1000 litres of water discharged by fire horse in a minute. In addition, fire quickly begins suppression within moments of detecting and this prevents further spread and the amount of water needed to put the fire off. When less water is used to put off fire, the result is less water runoff containing hazardous pollutants which can potentially impact the domestic or agricultural supply. In the UK, landfill is the Best Practicable Environmental Option or BPEO for certain waste type disposal. However, UK generates more waste than average European Union (Business sprinkler alliance 2013). Through the installation of sprinklers, little damage will be done on property thereby reducing the materials getting to landfill. The efficiency of sprinklers in environmental sustainability, safety protection and protection of property is enhanced by the installation of smoke detectors and conscious and inspecting one’s home from fire hazards. 2. Positive and negative impacts of fire on the society a. Positive impacts of fire on the society The most common and popular concept is that fire is damaging to the environment and should not be tolerated both in the field and forests. As people’s mindset increasingly became aware of fire as bad, any fire is quickly suppressed at any costs. The suppression of fire in forests and fields results to accumulation of combustible material on forest floor thereby resulting to large numbers and devastating wildfires. Prescribed fire is used as a tool to manage and conserve the forest ecosystem’s integrity (Brown, Baccus, Means and Forstner 2011). As a result, prescribed fires protect the forest and natural environment against wildfires and allow the evaluation of the impacts of fire on different vegetation types. In terms of air quality, controlled fires prevent larger fires on forests that which thereby prevents the risk of large amount of smoke in the air as a result of wild fires. Through controlled fires, the destruction of extensive forest areas is prevented which as a result improves the forage for consumption by wild animals. On the soil and soil biota, controlled burning results to increased amount of bases in the soil, the content of exchangeable magnesium, calcium and potassium tripled, phosphorus available in the soil increases, and organic matter did not decrease after burning. In addition, controlled burning did not affect the growth of trees in forest plantation and has proven important for the health of tree plantations. It is clear that fire plays a crucial role in nutrients, energy flow and food chain recycling. b. Negative impacts of fire on the society The main characteristic of fire is the consumption of oxygen and this makes it harmful to burning flammable items. Fires can burn down property and people, forests, vegetation and animals among others. Uncontrolled fires are characterized as being hot and of high intensity. Other factors associated with uncontrolled fires are fire duration and heat penetration rate. Uncontrolled fires on forests and property result to the release of much high smoke and particles compared to controlled fires. Through uncontrolled fires, it implies that there is high amount of release of soot, ash and sulfur compound particles which result to global dimming. When soot, sulfur and ash particles get into the atmosphere, water droplets form around them thereby increasing mirroring effect where the clouds reflect sunlight back into the space and increased global dimming result to increased atmospheric heat. In terms of wildlife, very hot uncontrolled fires results to the destruction of extensive natural forest which would affect wildlife. The destruction of wildlife due to uncontrolled fires is as a result of lack of equilibrium between given animal species and fire. Such fires destroy grass seeds, trees and other vegetation thereby affecting their health and the forage for wild animals. Through the destruction of forest tree bases, uncontrolled fires allow the formation and development of fungi at such tree bases. The fungi then enter the trees and reduce the value and quality of timber. Socially, fires result to destruction of local businesses and homes. This ends up cutting off the practical links that have people connected to each other. Uncontrolled fires result to the destruction of electricity, telephone lines and roads which connect people. Through the destruction of people’s property, uncontrolled fires result to financial problems as the affected people have to strain to get by and start over. 3. Importance of fire statistics and changing fire deaths trends since 2000-2010 Fire deaths in the UK include deaths by fire victims and fire fighters on duty. Across the globe, deaths and injuries related to fire are challenge to public health. In 2000, the world experienced 238,000 deaths and 10 million disability adjusted life years. The mortality and morbidity rates are highest are highest in older persons and children. According to Mulvaney et al. (2009), UK data revealed that children had the highest morbidity and mortality rates related to fires. The most affected children whose parents had never worked or parents who were not employed. Death to children of such parents resulted from the exposure to smoke, flames and fire 26 times higher than those of children from parents holding managerial occupations. It is also clear from the UK data that persons living in disadvantaged areas, in older housing and single-parent families had higher fire injury rates on the basis of social gradients. Fire death rates statistics in the UK by 2004 indicated that cooking appliances, heating appliances and smoker’s materials were the key factors associated with fire ignitions that result to fatal and non fatal fire injuries. According to info4fire.com, (2011), the fire death rates per million population in the UK was 7.6 and ranked ninth lowest death rate out of 24 industrialized nations. This reduction reflects reductions in the prevalence of smokers especially owing to legislation requiring cigarettes to be self extinguishing (Mulvaney et al. 2009). Another legislation that would have contributed to reduction in cigarette lighters’ fire is the requirement to use fire-retardant paper. Social inequalities in fire-based injuries and deaths were negligibly affected by safety interventions. The possession of working smoke alarms is associated with deprivation, low ownership levels in disadvantaged areas, poorer housing quality, single adult households, families of black and minority ethnic among others. Increased fire deaths and injuries among the older persons in the UK was associated to cognitive and physical impairment, social isolation, low income, need for heating of the household for most parts of the day and use of multiple medications. Reduction in fire deaths rates is associated with continued development of policies and legislations procedures to be accomplished by various sectors thereby reducing fire causes. Section II 1. Different states of matter and their molecular differences Matter take three different classical states which are gases, liquids and solids. In gas form particles are distinctly separated from each other and have no regular arrangement. In liquids, particles are close together but without regular arrangement while solids particles are tightly packed and usually in a regular pattern. While heated at 1000 water (liquid) turns into vapor or gas while cooling water below 00 turns to ice or solid. 2. Conversion of temperatures to Kelvin a. 127.50 = 127.5 +273.15=400.65K b. 2740 = 274+273.15 = 547.15K c. 4650 = 465+273.15 = 738.15K d. 1090 = 109 +273.15 = 382.15K 3. Balancing equations a. 2LiNO3 ­­­+ CaBr2 -> Ca(NO3)2 + 2LiBr b. AgNO3 + Li -> LiNO3 + Ag c. Si(OH)4 + 4NaBr -> SiBr4 + 4NaOH d. 2NaCN + CuCO3 -> Na2CO3 + Cu(CN)2 4. Litres of carbon dioxide formed at STP from complete combustion of 82.60g of ethanol, C2H5OH (l) The conversion involves changing from one unit to another and the two substances are involved in a chemical reaction, this is a stoichiometry problem Complete combustion of ethanol result to all carbon forming carbon dioxide and all its hydrogen forming water. C2H5OH (l) + 3O2 (g) -> 2CO2 (g) + 3H2O (l) Mass C2H5OH -> moles C2H5OH -> moles CO2 -> Volume of CO2 at STP L CO2=82.60g C2H5OH {1 mol C2H5OH /(46.0692g C2H5OH )}{2 mol CO2/(1 mol C2H5OH)}{22.414 l CO2/(1mol CO2)}STP = 80.37 L CO2 Where molar volume at STP is 22.414 L/mol for gases at 00 C and 1 atm of pressure 5. The empirical formula for benzene is CH. Its molecular weight was determined to be 78 g/mol. What is the molecular formula 78g/mol Carbon = 12.011g/mol and Hydrogen H = 1.008g/mol = 13 g/mol 78/13 = 6. The molecular formula is 6 times the empirical formula (CH) C6H6. The mass percentage of C 72/78 = 92.31% while H = 6/78 = 7.70% 78*.9230 = 71.994, 78*.0770 = 6.006 71.994/12= 6, 6.006/1 = 6 Molecular formula is C6H6 6. Mechanisms of fire extinction The four mechanisms of fire extinction are cooling, smothering, dilution or elimination of combustible element and control of flames or interruption of the chain reaction. Cooling involves lowering the combustible element’s temperature and the environment below ignition point. Smothering or extinguishing consists of isolating the combustion element and oxygen thereby reducing their concentration within the environment. Dilution of combustion element involves separating te combustible element from the heat source. Control of frames alters the release of free radicals produced in combustion. 7. Materials that undergo smouldering combustion Solid materials sustain a smouldering reaction like coal, cellulose, wood and cotton. 8. Boyles law states that the product of pressure and volume of a gas is a constant for the ideal gas PV= n Combined gas states that the volume and pressure of a gas are inversely proportional to each other but directly proportional to the gas’ temperature.P= V/T Ideal gas law relates the variables of pressure, temperature, volume and the number of moles of gas PV=nRT a. PV=nRT 5.1*15= 6*0.0820574*T; T= 76.5/.4923444= 155.3790K b. PV=nRT 1.2*26= 360*.0820574n => n= 1.2*26/(360*.0820574) => n= 31.2/29.540664 = 1.056 mol 9. Causes of incomplete combustion Incomplete combustion results from a combination of insufficient oxygen to allow a hydrocarbon fuel source to react completely with oxygen thereby yielding carbon dioxide and water. 10. Four categories of flames The four forms of flames are Laminar, premixed; Laminar, diffusion; turbulent, premixed; and turbulent, diffusion. Laminar premixed flame is that of a Bunsen burner, laminar diffusion is that of a candle, turbulent premixed from engineered combustion systems like boilers while turbulent diffusion flames are those of uncontrolled fires. Bibliography Brown, D, Baccus, J, Means, D and Forstner, M 2011, Potential positive effects of fire on juvenile amphibians in a southern USA Pine Forest, Journal of fish and wildlife management, Vol.2. No.2. P. 135-145. Business sprinkler alliance 2013, fire sprinklers and environmental sustability, viewed 18 January 2013, http://www.business-sprinkler-alliance.org/why-sprinklers/fire-sprinklers-and-environmental-sustainability/ Dyer J 2008, Effectiveness of Automatic fire sprinklers in high ceiling areas and the impact of sprinkler skipping. Fire engineering research report 08/3. Info4fire.com, 2011, US still lags behind UK in international fire death rates, viewed on 18 January, 2013 from http://www.info4fire.com/news-content/full/us-still-lags-behind-uk-in-international-fire-death-rates Mulvaney, C et al. 2009, Fatal and non-fatal fire injuries in England1995-2004: Time trends and inequalities by age, sex and area deprivation, Journal of Public Health, Vol. 31. No. 1. P. 154-161. Tabor, D 1991, Gases, Liquids and Solids: and other states of matter, Cambridge: Cambridge University press. Read More

2. Positive and negative impacts of fire on the society a. Positive impacts of fire on the society The most common and popular concept is that fire is damaging to the environment and should not be tolerated both in the field and forests. As people’s mindset increasingly became aware of fire as bad, any fire is quickly suppressed at any costs. The suppression of fire in forests and fields results to accumulation of combustible material on forest floor thereby resulting to large numbers and devastating wildfires.

Prescribed fire is used as a tool to manage and conserve the forest ecosystem’s integrity (Brown, Baccus, Means and Forstner 2011). As a result, prescribed fires protect the forest and natural environment against wildfires and allow the evaluation of the impacts of fire on different vegetation types. In terms of air quality, controlled fires prevent larger fires on forests that which thereby prevents the risk of large amount of smoke in the air as a result of wild fires. Through controlled fires, the destruction of extensive forest areas is prevented which as a result improves the forage for consumption by wild animals.

On the soil and soil biota, controlled burning results to increased amount of bases in the soil, the content of exchangeable magnesium, calcium and potassium tripled, phosphorus available in the soil increases, and organic matter did not decrease after burning. In addition, controlled burning did not affect the growth of trees in forest plantation and has proven important for the health of tree plantations. It is clear that fire plays a crucial role in nutrients, energy flow and food chain recycling. b. Negative impacts of fire on the society The main characteristic of fire is the consumption of oxygen and this makes it harmful to burning flammable items.

Fires can burn down property and people, forests, vegetation and animals among others. Uncontrolled fires are characterized as being hot and of high intensity. Other factors associated with uncontrolled fires are fire duration and heat penetration rate. Uncontrolled fires on forests and property result to the release of much high smoke and particles compared to controlled fires. Through uncontrolled fires, it implies that there is high amount of release of soot, ash and sulfur compound particles which result to global dimming.

When soot, sulfur and ash particles get into the atmosphere, water droplets form around them thereby increasing mirroring effect where the clouds reflect sunlight back into the space and increased global dimming result to increased atmospheric heat. In terms of wildlife, very hot uncontrolled fires results to the destruction of extensive natural forest which would affect wildlife. The destruction of wildlife due to uncontrolled fires is as a result of lack of equilibrium between given animal species and fire.

Such fires destroy grass seeds, trees and other vegetation thereby affecting their health and the forage for wild animals. Through the destruction of forest tree bases, uncontrolled fires allow the formation and development of fungi at such tree bases. The fungi then enter the trees and reduce the value and quality of timber. Socially, fires result to destruction of local businesses and homes. This ends up cutting off the practical links that have people connected to each other. Uncontrolled fires result to the destruction of electricity, telephone lines and roads which connect people.

Through the destruction of people’s property, uncontrolled fires result to financial problems as the affected people have to strain to get by and start over. 3. Importance of fire statistics and changing fire deaths trends since 2000-2010 Fire deaths in the UK include deaths by fire victims and fire fighters on duty. Across the globe, deaths and injuries related to fire are challenge to public health. In 2000, the world experienced 238,000 deaths and 10 million disability adjusted life years.

The mortality and morbidity rates are highest are highest in older persons and children.

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