Explosion static electricity

Dust Explosions Static Electricity Hazards of Vacuum Hazards of Inert Gases Gas Dispersion... 

An fuel-air mixture explosion can be initiated by a sudden discharge of static electricity. Yet, while flowing in systems, a fluid develops an electrical charge which will take as long to dissipate as the fluid is a poor conductor. The natural electrical conductivity of jet fuel is very low, on the order of a few picosiemens per meter, and it decreases further at low temperature. 

It is believed that to avoid any risk of explosion, the electrical conductivity of jet fuel should fall between 50 and 450 pS/m. This level is attained using anti-static additives which are metallic salts (chromium, calcium) added at very low levels on the order of 1 ppm. 

Mixing cellulose esters in nonpolar hydrocarbons, such as toluene or xylene, may result in static electricity buildup that can cause a flash fire or explosion. When adding cellulose esters to any flammable Hquid, an inert gas atmosphere should be maintained within the vessel (132). This risk may be reduced by the use of conductive solvents in combination with the hydrocarbon or by use of an antistatic additive. Protective clothing and devices should be provided. 

Standard on Explosion Frevention Sjstems, NFFM 69, and Static Electricity, NFFM 77, National Fire Protection Association, Quiucy, Me., 1984. 

Toluene is a notoriously poor electrical conductor even in grounded equipment it has caused several fires and explosions from static electricity. Near normal room temperature it has a concentration that is one of the easiest to ignite and, as previously discussed, that generates maximum explosion effects when ignited (Bodurtha, 1980, p. 39). Methyl alcohol has similar characteristics, but it is less prone to ignition by static electricity because it is a good conductor. Acetone is also a good conductor, but it has an equihbrium vapor pressure near normal room temperature, well above UFL. Thus, acetone is not flammable in these circumstances. 

Stores and work areas should be designated No Smoking areas and access controlled. Depending upon scale, explosion-proof electrics and static elimination may be required. 

On one occasion a tank truck was being splash-filled with gas oil, (lash point 60°C. The splashing produced a lot of mist, and it also produced a charge of static electricity on the gas oil. This discharged, igniting the mist. There was a fire with flames 10 m high but no explosion. The flames went out as soon as the mist had been burned. 

Static electricity (static for short) has been blamed for many fires and explosions, sometimes con ectly. Sometimes, however, investigators have failed to find any other source of ignition. So they assume that it must have been static even though they are unable to show precisely how a static charge could have been formed and discharged. 

Even if a static spark ignites a mixture of flammable vapor and air, it is not really correct to say that static electricity caused the fire or explosion. The real cause was the leak or whatever event led to the formation of a flammable mixture. Once flammable mixtures are formed, experience shows that sources of ignition are likely to turn up. The deliberate formation of flammable mixtures should never be allowed except when the risk... 

These explosions in air are usually the result of the release of flammable gas and/or mists by leaks, rupture of equipment, or rupture of safety relierdng devices and release to the atmosphere, which become ignited by spark, static electricity, hot surfaces, and many other... 

The checkers had n-bromobenzenediazon ium hexafluoro-phosphate examined in laboratories of the Du Pont Co. Explosives Department to see if it could be detonated. It was found sensitive to neither shock nor static electricity, and to decompose but not detonate when rapidly heated to 250°. Hence it probably does not present an explosion hazard, but it should be kept away from heat, especially if in a closed container. 

Spillage, 427, 428, 429 Spontaneous combustion, See Combustion Static electricity, 213, 214 Steam explosions, 19, 47, 219, 423 Storage, 401 drums, 403 LPG cylinders, 403 principles, 248... 

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. 

The worst hazard scenarios (excessive temperature and pressure rise accompanied by emission of toxic substances) must be worked out based upon calorimetric measurements (e.g. means to reduce hazards by using the inherent safety concept or Differential Scanning Calorimetry, DSC) and protection measures must be considered. If handling hazardous materials is considered too risky, procedures for generation of the hazardous reactants in situ in the reactor might be developed. Micro-reactor technology could also be an option. Completeness of the data on flammability, explosivity, (auto)ignition, static electricity, safe levels of exposure, environmental protection, transportation, etc. must be checked. Incompatibility of materials to be treated in a plant must be determined. 

I Spontaneous reaction Static electricity Physical explosions... 

On rubbing with a glass rod, a sample exploded violently. As the explosion could not be reproduced with a metal rod, initiation by static electricity was suspected. 

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