Fire Technology and Arson PDF

FIRE TECHNOLOGY AND ARSON PREL INVESTIGATIO IMS DEFINITION OF TERMINOLOGIES FIRE - Fire is the manifestation of rapid chemical reaction occurring between fuel and an oxidizer- typically the oxygen in the air. Such rapid chemical reaction releases energy in the form of heat an...

FIRE TECHNOLOGY AND ARSON PREL INVESTIGATIO IMS DEFINITION OF TERMINOLOGIES FIRE - Fire is the manifestation of rapid chemical reaction occurring between fuel and an oxidizer- typically the oxygen in the air. Such rapid chemical reaction releases energy in the form of heat and light. -The active principle of burning, characterized by the heat and light of combustion.(RA 9514) PYROLYSIS - “chemical decomposition of matter through the action of heat”. In this case, the decomposition causes a change from a solid state to vapour state. Of the vapour mixes sufficiently with air and heated to high temperature, combustion results. COMBUSTION - is a self – sustaining chemical reaction producing energy or products that cause more reactions of the same kind. Commonly known as burning SPONTANEOUS COMBUSTION - Is the process of catching fire as a result of heat generated by internal chemical action. FLAME - Are incandescent gases which accompanies brisk or rapid oxidation of any combustible material. The burning gas or vapor of a fire that is visible as light of various colors.  FIRE TRIANGLE VS FIRE FIRE TRIANGLE (GLOWING TETRAHEDRON MODE) OXYGEN FUEL HEAT FIRE TETRAHEDRON (FLAMING MODE) OXYGEN FUEL HEAT SELF-SUSTAINED CHEMICAL REACTION  FIRE FUEL ELEMENTS HEAT OXYGEN  FUEL (REDUCING AGENT) Is anything that will burn SOLID when heated with sufficient molecules are closely oxygen. It packed together is the most important part of LIQUID the triangle, for fuel is what molecules are loosely burns. The packed nature and properties of the GAS molecules are free to fuel are essential in combating fires. It comes in three form as move solid, liquid or gas.  THE SOLID FUELS Types of Flammable solids Non-pyrolyzable solid fuels – Pyrolyzable solid fuels – solid fuels that are difficult to include many of the ignite. A common example is ordinary accepted charcoal. Chemical combustibles: wood, paper decomposition does not occur and so on. because there are no pyrolyzable elements present.  THE LIQUID FUELS 2 GENERAL LIQUID FUELS ARE MAINLY MADE FROM PETROLEUM, BUT SOME GROUPS OF SYNTHETIC LIQUIDS ARE ALSO PRODUCED. PETROLEUM IS ALSO LIQUID FUELS CALLED CRUDE OIL. THEY MAY BE REFINED TO PRODUCE GASOLINE, DIESEL OIL, AND KEROSENE. Flammable liquids – they are liquids having a flash Combustible Liquids – point of 37.8 these liquids have °C (100°F) and a vapor flash point at or pressure not exceeding 40 above psia (2068.6 um) at 37.8 °C. 37.8 °C (100°F).  THE GAS Gaseous fuels are those in which molecules are in rapid FUELS movement and random motion. They have no definite shape or volume, and assume the shape and volume of their container. There are both natural and manufactured flammable gases. Gas fuels flow easily through pipes and are used to provide energy for homes, businesses, and industries. Examples of gas fuels are acetylene, propane, and butanes.  CLASSIFICATION OF GASES: BASED NATURAL GAS – The gas used ON SOURCE to heat buildings, cook food, and provides energy for industries. It consists chiefly of methane, a colorless and odorless gas. Natural gas is usually mixed with compounds of foul-smelling elements like sulfur so gas leaks can be detected.  CLASSIFICATION OF GASES: BASED MANUFACTURED ON GAS SOURCE – This gas like synthetic liquid fuels is used chiefly where certain fuels are abundant and others are scarce(limited). Coal, Petroleum, and Biomass can all be converted to gas through heating and various chemical procedures FUEL GASES – flammable gases usually used for burning with air CLASSIFICATIO to produce heat, utilize as power, light, comfort, and process. Most N OF commonly used gases are natural gas and the LPG (butane and GASES:ACCORD ING TO USAGE propane). INDUSTRIAL GASES - This group includes a large number of gases MEDICAL GASES – used for industrial processes as those used for those in welding and cutting treatment such as (oxygen, acetylene); refrigeration(freon, ammonia, sulfur anesthesia (chloroform, dioxide); chemical nitrous oxide); processing (hydrogen, nitrogen, respiratory therapy ammonia, chlorine); water (oxygen). treatment (chlorine, fluorine).  OTHER FUELS CHEMICAL FUELS NUCLEAR FUELS Chemical fuels, which are Nuclear fuels provide energy produced in solid and liquid through the fission or fusion of form, create great amounts of their atoms. heat and power. They are used Nuclear Fission – split of the chiefly in rocket engines. nucleus of atoms Chemical rocket propellants Nuclear Fusion – combination consist of both a fuel and an of two light nuclei of atom oxidizer. A common rocket fuel is the chemical hydrazine.  HEAT The energy component of the fire Temperature - temperature tetrahedron when heat comes into is the measurement of the contact with a fuel, the energy supports the combustion reaction degree of thermal agitation Source of ignition or any device to of molecules; the hotness or start a fire. It can be a safety match, a coldness of something. lighted candle, or of more Thermometer is the sophisticated forms such as a instrument used to measure chemical, mechanical or electrical temperature and commonly contrivance designed to start a blaze. expressed in °C, °F, and °K.  LATENT The quantity of heat absorbed by HEAT a substance when the substance from a solid to liquid, and from a liquid to gas. SUBLIMATION – solid to gas MELTING – Solid to liquid VAPORIZATION – Liquid to vapor/gas CONDENSATION – steam/vapor/gas to water  FIVE DIFFERENT TEMPERATURE SCALES ARE IN USE TODAY, THEY ARE: Celsius – it has a freezing point of 0°C and a boiling point of 100°C. It is widely used through out the world, particularly for scientific works. Fahrenheit – it is used mostly in English-speaking countries for purposes other than scientific works and based on the mercury thermometer. In this scale, the freezing point of water is 32°F and the boiling point is 212 °F. Kelvin or Absolute – it is the most commonly used thermodynamic temperature scale. Zero is defined as absolute zero of temperature that is, -273.15 °c, or –459.67 °F. Rankine – is another temperature scale employing absolute zero as its lowest point in which each degree of temperature is equivalent to one degree on the Fahrenheit scale. The freezing point of water under this scale is 492 °R and the boiling point is 672 °R.  TYPES OF ENERGY (COMMON SOURCES OF HEAT) THE MOST COMMON SOURCE OF HEAT IN COMBUSTION REACTIONS WHEN ANY COMBUSTIBLE IS IN CHEMICA L CONTACT WITH OXYGEN, OXIDATION OCCURS. THE REACTION OF THIS PROCESS RESULTS IN THE PRODUCTION ENERGY OF HEAT. EXAMPLE: HEAT GENERATED FROM BURNING MATCH, SELF HEATING (SPONTANEOUS  TYPES OF ENERGY (COMMON SOURCES OF HEAT) can generate temperature high enough to ignite any ELECTRIC combustible material near the heated area. AL EXAMPLE: ENERGY Overcurrent/ overload Sparking Arcing Static Lightning  TYPES OF ENERGY (COMMON SOURCES OF HEAT) Generated when atoms either split apart (fission) or combine (fusion) Example: fission heats water to drive steam NUCLEAR turbines and produce electricity solar energy is a product of a fusion ENERGY reaction an energy created by friction and MECHANIC compression Heat of friction - the movement of two surfaces against each other, thus AL ENERGY producing sparks Heat of compression - heat is generated when a gas is compressed in a container or cylinder CONDUCTION HEAT TRANSFER It is the transfer of heats by molecular activity with in a material or medium, usually a solid. Direct contact is the underlying factor in conduction. CONVECTION It is the transfer of heat through a circulating medium, usually air or liquid. Heat transfer by convection is chiefly responsible for the spread of fire in structures. RADIATION Radiated heat moves in wave and rays much like sunlight. Radiated heat travels the speed, as does visible light: 186,000 miles per second. A means of heat transfer when energy travels through materials and space as waves.  HEAT TRANSFER A colorless, odorless gas OXYGEN and one of the compositions of air (OXIDIZING which is approximately AGENT) 21% percent by volume Take note: Air composition: 21% normal oxygen is needed to 21% of normal produce fire in the presence of fuel 1 % other gases and heat. 12% oxygen is insufficient 78% nitrogen to produce fire, 14-15% oxygen can support flash point, and 16-21% oxygen can support fire point.  PROPERTIES OF PHYSICAL PROPERTIES A. SPECIFIC GRAVITY FIRE - the ratio of the weight of a solid or substance to the weight of an equal volume of water B. VAPOR DENSITY - the weight of volume of pure gas compared to weight of a volume of dry air at the same temperature and pressure C. VAPOR PRESSURE - the force exerted by the molecules on the surface of the liquid at the equilibrium D. TEMPERATURE - the measure of the thermal degree of the agitation of molecules of a given substance; the measure of the molecular activity within the substance  PROPERTIES OF E. BOILING POINT FIRE - the constant temperature at which the vapor pressure of the liquid is equal to the atmospheric pressure F. IGNITION TEMPERATURE - the minimum temperature to which the substance in the air must be heated in order to initiate or cause self-contained combustion without addition of heat from outside sources G. FIRE POINT - the temperature at which the material will give off ample vapors to keep burning H. FLASH POINT - the temperature at which the material is not hot enough to keep burning, but still gives off enough vapors to cause a flame across the surface  PROPERTIES OF CHEMICAL PROPERTIES FIRE ENDOTHERMIC REACTIONS – changes whereby energy (heat) is absorbed or is added before the reaction takes place. EXOTHERMIC REACTIONS – those that release or give off energy (heat) thus they produce substances with less energy than the reactants. OXIDATION – a chemical change that is exothermic, a change in which combustible material (fuel) and an oxidizing agent (air), react. Example of oxidation is combustion which is the same as actual burning (rapid oxidation) FLAMES – flames are incandescent (very bright/glowing with intense heat) gases. It is a combustion product and a manifestation of fire when it is in its gas-phased combustion.  LUMINOUS FLAME – is orange-red, deposit soot at TYPES OF the bottom of a vessel being heated due to FLAMES incomplete combustion and has a low temperature. NON-LUMINOUS FLAME – is BASED ON COLOR blue, there is complete AND combustion of fuel and has COMPLETENESS OF relatively high temperature. COMBUSTIBILITY OF FUEL  PREMIXED FLAME – is exemplified by a Bunsen-type TYPES OF laboratory burner where hydrocarbon (any substance FLAMES containing primarily carbon and hydrogen) is thoroughly mixed with air before reaching DIFFUSION FLAME –the flame zone. is observed when gas (fuel) alone is forced through a nozzle into the atmosphere which diffuses in the surrounding atmosphere in order to form a Based on Fuel flammable mixture. The candle flame is an example of diffusion flame governed purely and Air by molecular diffusion, and the flame of the oxyacetylene torch. (diffused – dispersed, Mixture widely spread) TURBULENT FLAME – are those having unsteady, irregular TYPES OF flows. As physical size, gas FLAMES density or velocity is increased, all laminar gas flows Based on tend to become turbulent. Smoothness LAMINAR FLAME – when a particle follows a smooth path through a gaseous flame.  DANGEROUS BEHAVIOR OF FIRE Fire is so fatal when the following conditions occurred: BACKDRAFT – it is the sudden and rapid (violent) burning of heated gases in a confined area that occurs in the form of explosion. This may occur because of improper ventilation. If a room is not properly ventilated, highly flammable vapors maybe accumulated such that when a door or window is suddenly opened, the room violently sucks the oxygen from the outside and simultaneously, a sudden combustion occur, which may happen as an explosion  DANGEROUS BEHAVIOR OF FIRE Flashover – it is the sudden ignition of accumulated radical gases produced when there is incomplete combustion of fuels. It is the sudden burning of free radicals, which is initiated by a spark or flash produced when temperature rises until flash point is reached. When accumulated volume of radical gases suddenly burns, there will be a very intense fire that is capable of causing flames to jump at a certain distance in the form of fireball. Fireballs can travel to  DANGEROUS BEHAVIOR OF FIRE Biteback - a fatal condition that takes place when the fire resists extinguishment operations and become stronger and bigger instead. Flash Fire – better known as dust explosion. This may happen when the metal post that is completely covered with dust is going to be hit by lightning. The dust particles covering the metal burn simultaneously thus creating a violent chemical reaction that produces a very bright flash followed by an explosion.  THE THREE STAGES OF FIRE INCIPIENT FREE BURNING SMOLDERING PHASE (INITIAL PHASE PHASE STAGE)  INCIPIENT PHASE (INITIAL STAGE) INITIAL STAGE OF FIRE NORMAL ROOM TEMPERATURE THE PYROLYSIS PRODUCTS ARE MOSTLY WATER VAPOR AND CARBON DIOXIDE, SMALL QUANTITIES OF CARBON MONOXIDE AND SULFIDES MAYBE  FREE BURNING PHASE a phase of burning in which materials or structures are burning in the presence of adequate oxygen accelerated pyrolysis process take place occurrence of  SMOLDERING PHASE final phase of burning wherein flame ceases but dense smoke and heat completely fill the confined room when sufficient supply of oxygen is introduced, backdraft occurs  IGNITION Describes the period when the four elements of the fire tetrahedron come together and combustion begins. PHASES OF  GROWTH shortly after ignition, a fire plume begins to form above the burning fuel. As the plume develops, it begins to draw or entrain air from the surrounding space into the column. PHASES OF  FLASHOVER During flashover, conditions in the compartment change very rapidly as the fire changes from one that is dominated by the burning of the materials first ignited to one that involves all of the exposed combustible surfaces within the compartment. PHASES OF  FULLY- DEVELOPED occurs when all combustible materials in the compartment are involved in the fire PHASES OF  DECAY as the fire consumes the available fuel in the compartment, the rate of heat released begins to decline. PHASES OF Thank you for listening!