Flash point Classification and labelling of flammable liquids depends on the flash point of the liquid. Definition Flash point The temperature at which enough vapour escapes from a liquid that an ignitable mixture is created with the ambient air (EN 1127-1). Explosion limits Explosion limits are the minimum or maximum concentration levels of vapour of a flammable or combustible material (expressed as percent by volume in air) at which an explosion will occur in a confined area if an ignition source is present. No explosion can occur in the presence of very low or very high concentrations. Definition ignition temperature Ignition temperature (of a flammable gas or liquid) is the lowest temperature of a hot surface, determined under prescribed test conditions, at which ignition of a flammable substance occurs as a gas-air or vapour-air mixture. The fire triangle The basis for the handling of hazardous materials is knowledge of the fire triangle. This clearly illustrates that a fire or an explosion is only possible if three conditions are fulfilled: Combustible substance Ignition source Oxygen Examples of flash points of flammable liquids Material Flash point °C Ether (diethyl ether) -40 °C Petroleum ether / light petrol < -20 °C Petrol < -20 °C Diesel / Heating oil / Gas oil > 55 °C Petroleum / Turpentine / Kerosene 30–40 °C Ethanol 12 °C Propanol 12 °C Acetone < -20 °C MEK (butanone) -1 °C 0 % 100 % UPPER EXPLOSION LIMIT (UEL) LOWER EXPLOSION LIMIT (LEL) RICH MIXTURE non explosive EXPLOSIVE MIXTURE LEAN MIXTURE non flammable, non explosive SOURCE OF IGNITION: Mechanical spark Electrical spark Chemical reaction Electrostatic discharge Hot surface Open flame COMBUSTIBLE MATERIAL: Gas Liquid Solid OXYGEN Proportion OXYGEN SOURCE OF IGNITION COMBUSTIBLE MATERIAL EX °C Temperature of the liquid above the flash point Temperature of the liquid below the flash point "Lean mixture" IGNITABLE VAPOUR-AIR MIXTURE FLASH POINT 60° 23° 0° Please observe local legislation and regulations. 27
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