Explosion: An Experimental Study

There is conventional definition of materials that can be considered as nontoxic or toxic. The time of toxic materials exposure have to be studied altogether with the material fundamental toxicity when acceptable limits of long term hazard concentrations are to be fixed for exposed workers. The threshold limit value is material concentration assumed that the average worker may be exposed to, without harmful effects for 8 working hours during 5 days in a week, and it represents the mostly used guidance for the control of the workers long term exposures to air that is contaminated with toxic materials. These concentrations are usually given in ppm for gases and vapors, or in mg/m3 for aerosols and dusts. An encyclopedic data source about

The explosions may happen even without presence of fire, in cases when plant failure is caused by overpressure in an air receiver or of a steam receiver or boiler. This could be avoided by proper installation of pressure relief devices on air receivers or on a steam boilers and receivers.

When considering the explosions of mixtures that are flammable it is significant to understand difference between deflagration and detonation. Detonation of a mixture spread the reaction zone at velocities that are supersonic with shock compression as the main heating mechanism of the mixture. In case of deflagration the combustion process is identical to the normal (common) burning of a gas mixture. The combustion zone in case of deflagration spreads at velocities that are subsonic, and the build up of the pressure is slow. Factors determining whether deflagration or detonation in gas air mixtures will happen are numerous and include ignition source and concentrations of components in the gas mixture. Most materials do not detonate unless they are confined in some reservoirs or set on fire by some source with high ignition power - detonator. Nevertheless, even the pressure wave that are induced by deflagration may lead to damage that is not

Fire hazard

The sparking of motors and other electrical equipment is considered as a major potential source of ignition in plants, and nonflammable equipment is usually specified. Although on chemical plants cautions for elimination of ignition sources are regularly taken, best working principle should be presumption that any flammable material leakage will sooner or later find an source of ignition, or in other words to prevent any leakage.

The areas where ignitable concentrations of flammable gases will probably be present in regular operating conditions, necessarily safe equipment, or the equipment that is enclosed in a chambers that are gas-tight and purged, must be specified.

In areas where a flammable mixture will only be present under abnormal circumstances, non-sparking equipment can be specified (equipment that normally does not spark, but could spark if a fault develops). Some risk is involved, but the coincident failure of the electrical equipment and leak of flammable gas would be required to cause a fire or explosion. The application of any electrical equipment in areas with fire hazard is described or analyzed by many standards [20,