Flame-proof equipment

The sparking of electrical equipment, such as motors, is a major potential source of ignition, and flame proof equipment is normally specified. Electrically operated instruments, controllers and computer systems are also potential sources of ignition of flammable mixtures. 

The AMDR is equipped with some instruments that are used to detect the surrounding environment and transfer information back to the control centre. The explosion risk is very high when these instruments and equipments in service. So, we should use the intrinsically safe electrical equipment or other special design for the electrical equipment. In principle, the flame-proof equipment is not allowed to use in mine. But the intrinsically safe electrical equipment is very rarely at present, especially the power supply, motor and other key equipments. Therefore, the AMDR adopted the safety strategy of flame-proof after the redundant safety measures drawn up in the case of the basic principles of electric explosion-proof allowed. 

Specify intrinsically safe equipment, or flame-proof enclosures enclosures with pressurizing and purging. 

Quenching the vapour with cold air in the chamber may increase the rate of heat removal although excessive nucleation is likely and the product crystals will be very small. Condenser walls may be kept free of solid by using internal scrapers, brushes, and other devices, and all vapour lines in sublimation units should be of large diameter, be adequately insulated, and if necessary, be provided with supplementary heating to minimise blockage due to the buildup of sublimate. One of the main hazards of air-entrainment sublimation is the risk of explosion since many solids that are considered safe in their normal state can form explosive mixtures with air. All electrical equipment should therefore be flame-proof, and all parts of the plant should be efficiently earthed to avoid build-up of static electricity. 

Explosive, flammable and toxic liquid. Should be stored and used in closed systems whenever possible. Work areas should be adequately ventilated, and should be free from open lights, flames, and equipment that is not explosion-proof. Handle in hood. May polymerize spontaneously, particularly in the absence of oxygen or on exposure to visible light. Polymerizes violently io the presence of concentrated alkali. On standing may slowly develop a yellow color particularly after excessive exposure to light, hp 77.3 bpsoo 64.7° bp2b, 45.5° bp--, 23,6° bp,<, 8.7°. mp -83.55°. d 0.8060 df 0.8004. ng 1.3888. Flash pt. open cup 32°F (0°C). Explosive mixtures in air at 25° 3.05% low... 

The national standards for the coal mine equipment shell material are clear. But the material is not ruled strictly for the mine robot flame-proof enclosure. The cast steel, ordinary mine equipment shell material, couldn t meet the requirements of the AMDR obviously with high precision and high maneuver performance. Light alloy with low density and high intensity is the best choice of the AMDR flame-proof encloser material. 

All nearby electrical equipments and fittings shall be flame proof. 

Isolating Isolating the hazard is achieved by restricting plant and equipment. Eor example, in case of hazardous area, process transmitters use flame proof enclosure or use IS circuit so that hazard does not reach electrical circuit or sufficient energy does not reach the hazardous area. 

Store and use dichlorosilane only in adequately ventilated areas. It should be used only in a closed system constructed with compatible materials and designed to withstand the pressures involved. Keep away from heat and all ignition sources such as flames and sparks since dichlorosilane will form flammable mixtures with air and other oxidizing agents. All lines, connections, equipment, and so forth, must be thoroughly checked for leaks and grounded prior to use. Use only spark-proof tools and explosion-proof equipment. 

Use methyl chloride in a well-ventilated area only, preferably using a hood with forced ventilation. The cylinder should never be directly connected to a container of liquid since reverse flow can occur causing a reaction within the cylinder. To prevent reverse flow, a trap, check valve, or vacuum break should be inserted into the line. Cylinders of methyl chloride should be stored and used only in well-ventilated areas away from heat and all sources of ignition such as flames and sparks in order to avoid fire and explosion hazards. Flames should never be used to detect methyl chloride leaks use a soapy water solution. Do not use methyl chloride around sparking motors or other nonexplosion-proof equipment. Reserve stocks of methyl chloride cylinders should not be stored with... 

Store and use cylinders of vinyl chloride in well-ventilated areas away from heat and all sources of ignition such as flames and sparks. Do not use vinyl chloride around sparking motors or other equipment that is not explosion-proof equipment. Do not store reserve cylinder stocks of vinyl chloride with cylinders containing oxygen, chlorine, or other highly oxidizing or combustible materials [4]. 

Non-electrical equipment of the equipment group II, category 2 for explosive atmosphere formed from air and gases, vapours and/or mists, type of protection flame-proof enclosure, permissible explosive atmosphere of the Ex-Group IIB, T-Class T4, ambient temperature (T ) with 0°Cdiffering from the standard values -20 °C < T. -t-TO C ... 

Equipment described as explosion-proof is equipment installed in enclosures that will withstand internal explosions and also prevent the propagation of flame to the external atmosphere. As the gases generated by the explosion expand, they must be cooled before reaching the surrounding atmosphere. 

More recently, the NFPA has used the MESG and the MIC ratio for classifying explosion-proof electrical equipment (NFPA 497 1997), and this approach can also be used for classilying flame arresters. In this method, NEC Class I combustible materials (vapors or gases) are divided into four groups ... 

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