Basic fire science and fire extingusing techniques
- 1. BASIC FIRE SCIENCE AND FIRE EXTINGUSING MEDIA & TECHNIQUES. BY PRATHAP M D SECURITY PROFESSIONAL
- 2. AGENDA • Fire triangle • Transmission of heat-Conduction, Convection and Radiation • Classification of fire • Sources of ignition • Methods to extinguish fire-Starvation, Smothering, Coiling and Inhibition • Fire extinguishing agents-Water, Foam, CO2, Dry chemical, Dry powder, Fire blanket. • Types of fire extinguishers and color coding. • Fire extinguishing technique using portable fire extinguisher-PASS.
- 3. FIRE F-Find the fire locality. I-Inform everyone pulling the MCP,Calling command center etc. R-React immediately-Isolating burning material from the scenario, decide what type of fire and decide what type of extinguisher to be used E-Extinguish the fire with right fire extinguisher
- 4. FIRE TRIANGLE FIRE IS THE CHEMICAL REACTION BETWEEN THREE ELEMENTS SUCH AS Oxygen, Heat and Fuel. Oxygen-Its common in the atmospheric air. Heat- A source of ignition sufficient to initiate and propagate the chemical reaction of combustion. Heat travels though conduction, convection and radiation Fuel-Combustible substances in the for of vapor, liquid or solid. Examples- Wood, Paper, Petroleum products, Plastic, combustible gas etc.
- 5. IGNITION TEMP,FLASH POINT, FIRE POINT. IGNITION TEMP : The min temp at which fuel will ignite without help of ignition source. it also called "auto ignition temp". FLASH POINT : The min temp at which the rate of vaporization of fuel is sufficient to produce a momentary flash upon the application of source of ignition. FIRE POINT : The min temp at which the burning vapor is capable to enable combustion continue.
- 6. TRANSMISSION OF HEAT Transmission of heat happens through Conduction, Convection and Radiation • Conduction-Conduction usually happens in solid. Heat transfers from one molecule to another molecule of the metal is called conduction. Example for conductive metals are Copper, Aluminum, Brass, Steel, Bronze etc.
- 7. • Convection-Convection happens in liquid only. When water is heated it becomes less denser and low denser water moves down to replace less denser water causing a circular motion is called convection. Example:-Boiling water on stove, Radiators etc.
- 8. • Radiation-Radiation is energy travelling through space. Sunshine is the most familiar for of radiation. The Radiation refers to the emission of energy in rays or waves. Heat travels in a straight line. Sometimes radiation travels through glass windows and concentrate on one object inside the building and cause fire. Below is the best example for radiation which causes Fire.
- 9. CLASSIFICATION OF FIRE 1. CLASS A (SOLID FIRE)- Ordinary combustible such as wood, paper, cloth, trash and plastics. 2. CLASS B (LIQUID FIRE)- Flammable liquids such as gasoline, petroleum oil, alcohol, varnish and paints. 3. CLASS C (GASEOUS FIRE)-Flammable gases like propane, butane, hydrogen, Gasoline and natural gases. 4. CLASS D (COMBUSTIBLE METALS)-Sodium, Potassium , Magnesium, lithium and titanium. 5. CLASS E (ELECTRICAL FIRE)-Short circuits, electrical equipment, electrical shocks, improper wirings etc. 6. CLASS F (COOKING OILS)- FAT, GHEE, OILS USED FOR COOKING ETC. In US system class B and C is combines and called as Class B. In Australian/European system B and C is separated. In US system class C is called Electrical fire and in Aus. Eurp called as Class E.
- 10. SOURCES OF IGNITION OPEN FLAME ELECTRICAL SPARK HOT GASES HOT SURFACES CHEMICAL REACTION MECHANICAL SPARK WELDING SMOKING BATTERIES
- 11. METHODS TO EXTINGUISH FIRE 1) STARVATION-Removal of fuel by cutting fuel supply. Examples Removal of surrounding combustible materials Turning off a gas supply Blanking of a pipeline Turning off petroleum pipe lines.
- 12. 2) SMOTHERING-REMOVAL OF OXYGEN. Examples Covering a blanket or wood to prevent small fire in a drum. Smothering a frying pan blaze with a fire blanket Covering a candle with a glass Covering a waste bin with fire blanket to prevent oxygen supply. Closing the doors of the closed cabins. Using CO2 and DCP extinguishers.
- 13. 3) COOLING-REMOVAL OF HEAT. Cooling the burning material is the most common method used in extinguishing fire involving solid materials. Examples Using water type (CO2 CARTRIDGE TYPE) Water stored pressure type-using hydrant system Water bucket
- 14. 4) INHIBITION-STOPPING THE CHAIN REACTION Some extinguishing agents such as dry chemical powder interrupt the flame producing by cutting off the chemical chain reaction of the substance. Which can be used for Class B and C FIRE. DCP extinguishers puts out fire by coating the fuel surfaces with chemical powder. This separates the fuel from the oxygen in the air and prevent vapor formation. The powder also interrupts the chemical chain reaction of fire.
- 15. FIRE EXTINGUISHING AGENTS 1)WATER-Water is the most common extinguishing agents used for A type fire or solid fire. Water can be used in portable fire extinguishers through hydrant system, sprinkler system also used by fire brigades. Water extinguish the fire by taking away the heat element of the fire triangle, which is called as cooling. Water should not be used on Class B and Class C fire. It will spread the flammable liquid in class b fire and create shock hazard on class C fire.
- 16. 2) FOAM-A fire fighting foam is simply a mass of small air filled bubbles, which have lower density than oil, gasoline or water. Foam is made up of three elements such as water, foam concentrate and air. When mixed these three elements form a foam blanket. Foam separates the flames source from the fuel surface. By applying foam we can extinguish the fire by smothering that is taking off the oxygen from the fire triangle. Foam extinguishers are used for Class B fire.
- 17. 3) CARBON DIOXIDE-Carbon dioxide is a non-conductive and non corrosive gas used to reduce the amount of oxygen available to the fire. Carbon dioxide is extracted from the atmosphere and stored at high pressure in the liquid state within a fire extingushers.Carbon dioxide is suitable for Class B(flammable liquids) and Class C (electrical fire). Carbon dioxide mainly extinguish the fire by smothering that is taking out the oxygen supply in fire triangle.
- 18. 4) DRY CHEMICAL- The Dry Chemical Extinguisher removes the chemical reaction of a fire. In this category the multi-purpose Dry Chemical extinguisher is the most used fire extinguisher of all extinguishers because it is effective on Class A, Class B and Class C fires. This is an excellent fire extinguisher because it creates a barrier between the oxygen and fuel elements on Class A fires. Dry Chemical Extinguisher and not a multi-purpose Dry Chemical extinguisher, only use it on Class B and Class C fires.
- 19. 5) DRY POWDER- Similar to the dry chemical extinguisher, dry powder separates fuel from oxygen or removes the heat element of a fire. Dry powder extinguishers are used on Class D (combustible metal fires) only. They will not be effective on any other type of fire class. Dry powder mainly extinguish the fire by inhibition method.
- 20. 6) FIRE BLANKET-A fire blanket is a highly flame-resistant blanket that can be used to extinguish a small fire or to wrap around a person in case of a fire. Fire blankets are made from 2 layers of woven glass fiber fabric and an inner layer of fire retardant film. They work by cutting off the oxygen supply to the fire. Mainly fire blanket uses the method of smothering in extinguishing fire.
- 21. TYPES OF FIRE EXTINGUISHERS AND COLOR CODING TYPE CLASS COLOR CODING IMAGE WATER A (SOILID) RED FOAM A(SOLID) & B(LIQUID) CREAM CO2 B(LIQUID) ,E (ELECTRICAL) BLACK DRY POWDER A, B C , BC or D BLUE
- 22. FIRE EXTINGUISHING TECHNIQUE USING PORTABLE FIRE EXTINGUISHER-PASS 1) Pull the pin. Every fire extinguisher has a pin inserted into the handle that prevents the fire extinguisher from being discharged by accident. Grab the ring and pull the pin out from the side of the handle. 2) Aim the hose at the base of the fire. Hold the lower handle lever (the carrying handle) with one hand and grab the hose or nozzle with the other hand. Point the hose directly at the base of the fire, because you have to put out the fuel that’s burning. Do not aim the hose at the flames. 3) Squeeze the lever. To release the extinguishing agent, squeeze the two levers together with one hand while you aim the hose at the base of the fire with the other. Apply slow and even pressure when you squeeze the levers 4) Sweep the hose from side to side. To extinguish all the fuel, slowly sweep the hose back and forth over the base of the fire as you discharge the extinguisher. Move closer to the fire as the flames die down