Explosive limits in air

Diketene is a flammable Hquid with a flash point of 33°C and an autoignition temperature of 275°C. It decomposes rapidly above 98°C with slow decomposition occurring even at RT. The vapors are denser than air (relative density 2.9, air air = 1). The explosive limits in air are 2—11.7 vol % (135). In case of fire, water mist, light and stabilized foam, as well as powder of the potassium or ammonium sulfate-type should be used. Do not use basic extinguisher powders and do not add water to a closed container. 

Butylenes are not toxic. The effect of long-term exposure is not known, hence, they should be handled with care. Reference 96 Hsts air and water pollution factors and biological effects. They are volatile and asphyxiants. Care should be taken to avoid spills because they are extremely flammable. Physical handling requires adequate ventilation to prevent high concentrations of butylenes in the air. Explosive limits in air are 1.6 to 9.7% of butylenes. Their flash points range from —80 to —73° C. Their autoignition is around 324 to 465°C (Table 2). Water and carbon dioxide extinguishers can be used in case of fire. 

Oxygen, the second requirement for combustion, is generally not limiting. Oxygen in the air is sufficient to support combustion of most materials within certain limits. These limitations are compound specific and are called the explosive limits in air. The upper and lower explosive limits (UEL and LEL) of several common materials... 

Name Flashpoint °F Explosive Limits in air % by Volume Density... 

By far the most important sulfide is CS2, a colourless, volatile, flammable liquid (mp — 111.6°, bp 46.25°, flash point —30°, autoignition temperature 100°, explosion limits in air 1.25 50%). Impure samples have a fetid almost nauseating stench due to organic impurities but the purified liquid has a rather pleasant ethereal smell it is very poisonous and can have disastrous effects on the nervous system and brain. CSt was formerly manufactured by direct reaction of S vapour and coke in He or steel retorts at 750 1000°C but, since the early 1950s, the preferred synthesis has been the catalysed reaction between sulfur and natural gas ... 

Explosive limits in air, % by vol. Auto- ignition temperature. °F Specific gravity (water = 1.0) Vapor density (air = 1.0) Melting point. °r Boiling point or range. °F Water solu- bility Suitable extin- guishing agents Hazard... 

Hazard, i.e. the potential of the material to cause injury under certain conditions (flammability, explosion limits in air, ignition and autoignition temperatures, static electricity (explosions have occurred during drying due to static electricity), dust explosion, boiling point, fire protection (specification of extinguishers, compounds formed when firing), R S (nature of special risk and safety precautions). Table 5.2-5 lists hazards associated with typical chemical reactions. 

For leak detection, the sensor must be sensitive and fast enough to provide early leak detection so that action can be taken before the explosive limit in air is reached. Utilizing a fiber-optic sensor configuration could provide the best chance of meeting fast response and inexpensive and reliable goals. 

LEL Lower explosive limit in air, expressed as a percentage by volume. 

Molecular weight (kg/kmol) Specific heat capacity at 293 K (kJ/kg K) Density at 293 K (kg/m3) Latent heat evaporation (kJ/kg) Boiling point (K) Explosive limits in air at 293 K (per cent by volume) low high Solubility in water at 293 K (kg/m3)... 

The results for lower (LEL) and upper (UEL) explosive limits in air are presented in Table 3-1. The LEL and UEL values are the lower and upper concentrations (expressed as volume %) for flammability. The tabulation also provides the freezing and boiling point temperatures which are helpful in determining whether the substance is a gas, liquid or solid at ambient conditions. The tabulation is based on both experimental data and estimated values. 

The lower and upper explosive limits in air are often needed for gas mixtures. The Le Chatelier equation (2) for gas mixtures is ... 

Example 2 Estimate the lower (LEL) and upper (UEL) explosive limits in air for the gas mixture below ... 

Table A4. The permissible exposure limit (PEL) and IDLH, the flashpoint and autoignition temperature, and the explosive limits in air of green solvents. 

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