Domain 5 - Fire Protection and Prevention PDF

an sm rO Domain 5 Fire Protection and Prevention i 10.59% es od g.M En 34 Modesir Osman -IdipNEBOSH  Definitions:...

an sm rO Domain 5 Fire Protection and Prevention i 10.59% es od g.M En 34 Modesir Osman -IdipNEBOSH  Definitions: Chemical reaction that occurs between a fuel and an oxidizing agent that produces Combustion energy, usually in the form of heat and light. Heat of The amount of heat in calories evolved by the combustion of 1 g weight of a combustion substance. Combustible Any liquid having a flash point at or above 140°F and below 200°F liquid an Any liquid having a flash point below 140°F and having a vapor pressure not Flammable liquid exceeding 40 psia at 100°F The minimum temperature at which a liquid gives off vapor within a test vessel in Flash point sufficient concentration to form an ignitable mixture with air near the surface of the sm liquid. The flash point is normally an indication of susceptibility to ignition. The maximum concentration of a combustible substance capable of propagating a Upper flame through a homogeneous combustible mixture. UFL usually expressed in volume flammability limit percent. The lower end of the concentration range of a flammable solvent at a given rO Lower temperature and pressure for which air/vapor mixtures can ignite.LFL usually flammability limit expressed in volume percent. Classification of Fires i es A fires involve common combustibles such as wood, paper, cloth, rubber, trash, and Class A plastics. Involve flammable liquids, gases, solvents, oil, gasoline, paint, lacquers, tars, and other Class B synthetic or oil-based products. od Energized electrical equipment, such as wiring, controls, motors, data processing Class C panels, or appliances. Class D.M Involve combustible metals such as magnesium and sodium. Involve combustible cooking media such as oils and grease commonly found in Class K commercial kitchens. g En The new labeling system for fire extinguishers uses pictures to indicate what types of fires extinguishers can be used on and red diagonal lines through the types of fires they should not be used on. The number ratings on FE to indicate how large a fire they can contain. E.g, Class A extinguishers numeric rating of 1, which would indicate 1 gal of extinguishing material. The number ratings on Class B or C fire extinguishers indicate how many square feet of coverage the unit will contain.e.g 5BC indicates a 5 ft2 of coverage area for Class B and C fires 35 Modesir Osman -IdipNEBOSH  an sm i rO es od Exceptions of FE hydrostatic test :  When the unit has been repaired by soldering, welding, brazing, or use of patching compounds.  When the cylinder or shell threads are damaged..M  When there is corrosion that has caused pitting, including corrosion under removable name plate assemblies.  When the extinguisher has been burned in a fire;  When a calcium-chloride-extinguished agent has been used in a stainless g steel shell. En 36 Modesir Osman -IdipNEBOSH  Automatic Sprinkler Systems Dry Pipe Systems: Installed in areas where there is a potential for freezing, Wet Pipe Systems: which would render the system basically inoperable when More frequently installed systems. water is present at needed. E.g, dry pipe systems are normally installed in all times inside the piping distribution system. parking garages, unheated buildings. Once the sprinkler head is opened, the water in the Dry pipe systems cannot be installed unless the range of distribution system will flow out of the distribution ambient temperatures reaches below 40°F. an system. Water is not present in the pipe until the system is triggered and the water is released into the distribution system. sm Deluge Systems: Installed in areas where there are special hazards where the rapid spread of fire is a major concern. Heat sensors from the sprinkler heads have been Water Spray Systems: rO removed by design. Operate in same fashion as deluge system. There is no water stored in the distribution system. The piping and discharge nozzle spray patterns are The water is released into the piping distribution designed to protect a uniquely configured hazard. system by the activation of a deluge valve, which is Such patterns are designed for three dimensional activated by a fire alarm system. components or equipment Must be manually reset, by resetting the deluge valve. i Are designed to cover the floor area of a space. es Preaction Systems: od Basically hybrids of wet, dry, and deluge systems. An water supply valve is added to a dry pipe system. The valve itself is opened by the activation of Foam Water Sprinkler Systems: a fire detection system, such as a fire alarm or smoke Foam water sprinkler systems discharge a mixture of.M detector. water and low expansion foam concentrate. Normally placed in areas where accidental Used in areas that have high challenge fires, such as discharge is undesirable. Typical areas include data flammable liquids and airport hangars. centers, museums, and art centers. g En 37 Modesir Osman -IdipNEBOSH  NFPA 13, Standard for the Installation of Sprinkler Systems. The maximum spacing allowed between sprinklers in a light-hazard occupancy area is 15 feet. Light- hazard areas are those where the quantity and/or combustibility of contents is low and where fires with relatively low rates of heat release are expected, such as an office area. Ordinary-hazard occupancy areas also have a maximum allowable spacing of 15 feet between sprinkler heads. Extra-hazard occupancy areas have a maximum allowable spacing of 12 feet between sprinkler heads. an sm i rO es od.M Flash Point g Minimum temperature at which a liquid gives off vapor within a test vessel in sufficient concentration to form an ignitable mixture with air near the surface of the liquid. En Vapor Pressure The pressure exerted by the molecules that escapes from the liquid to form a separate vapor phase above the liquid surface. The pressure exerted by the vapor phase is called the vapor or saturation pressure. Vapor or saturation pressure depends on temperature. If fluids consist of more than one component, then components with high vapor pressures are called light components and those with lower vapor pressures are called heavy components. 38 Modesir Osman -IdipNEBOSH  Fire Point The temperature at which a substance will give off a vapor that will burn continuously after ignition. Usually, the fire point is higher than the flash point. Flammable and Explosive Limit Ranges an Concentrations between the lower and upper limits of the mixture are flammable or explosive. The lower flammable limit (LFL) or the lower explosive limit (LEL) is the leanest mixture that is still flammable or explosive. Conversely, the upper flammable limit (UFL) or upper explosive limit (UEL) is the richest mixture that is still flammable or combustible. These concentrations are given in percentage of air. sm Autoignition Temperature Also referred to as kindling point, is the lowest temperature at which a substance will ignite in a normal atmosphere without an external source of ignition from a spark or flame. The temperature rO at which a chemical will ignite decreases as the pressure increases or oxygen concentration increases. Specific Gravity i Specific gravity describes the density of a liquid compared to the density of water. Those liquids es with a specific gravity of one or less (≤1) are lighter than water and those with specific gravities of greater than or equal to one (≥1) are heavier than water. The specific gravity is particularly important when addressing chemical spills od Vapor Density Vapor density is the measure of the density of a substance compared to air. Those gases and vapors with densities greater than or equal to one (≥1) are heavier than air and will tend to sink to lower levels. Those gases and vapors with densities less than or equal to one (≤1) are lighter than.M air and will tend to float upward. Knowing the vapor density of a substance is useful in determining the location of the ventilation system. g Evaporation Rate Is the rate at which a liquid is converted to vapor at a given temperature and pressure. Butylacetate, En which has an evaporation rate of 1, is the standard by which most substances are compared to. Therefore, if a substance has an evaporation rate of less than 1, it will evaporate more quickly than butylacetate. 39 Modesir Osman -IdipNEBOSH  Water Solubility (Sw) Is the maximum amount of a substance that can dissolve in water at equilibrium at a given temperature and pressure. (Sw) values are usually expressed as moles of solute per liter. The term water solubility is primarily used in many environmental studies to help determine the fate of chemicals in the environment. an Boiling Point The temperature at which the vapor pressure of the liquid is equal to the environmental pressure surrounding the liquid. It is the temperature point where the liquid is converted sm into a vapor. Storage Requirements for Flammable and Combustible Liquids i rO es od g.M En 40 Modesir Osman -IdipNEBOSH  Inside Storage Rooms for Flammable or Combustible Liquids Storage room shall be equipped with either a gravity or a mechanical exhaust ventilation system. This system shall be designed to provide for a complete change of air within the room at least six times per hour. In addition, in each inside storage room, there shall be maintained one clear aisle at least 3 ft wide. Containers over 30 gal capacity will not be stacked one upon the other. an sm Fire “RACE” rule i rO es “Compressed gas” R = Rescue/remove all occupants A = Activate the alarm system (1) Is: A gas or mixture of gases in a container C = Confine the fire by closing doors having an absolute pressure exceeding 40 (psi) at E = Evacuate/extinguish 70°F (21.1°C), or od OSHA’s Portable Fire Extinguishers standard (2) Is a gas or mixture of gases having an absolute requires that a fire extinguisher be placed within 75 pressure exceeding 104 psi at 130°F (54.4°C) ft for Class A fire risk ,and within 50 ft for high-risk regardless of the pressure at 70°F (21.1°C), or Class B fire risk. (3) Is a liquid having a vapor pressure exceeding The two most common types of extinguishers in the 40 psi at 100°F (37.8°C) as determined by ASTM.M chemistry laboratory are pressurized dry chemical (American Society for Testing and Materials). (Type BC or ABC) and carbon dioxide. g The priorities of emergencies are universal and listed in increasing order:  Safety of people En  Protection of property  Cleanup and salvage  Restoring operations 41 Modesir Osman -IdipNEBOSH