【Daily Question 20090212】What are the different types of explosion-proof electrical equipment?

1 Explosion-proof control boxes 2 Explosion-proof starters 3 Explosion-proof control switches 4 Explosion-proof command devices 5 Explosion-proof wiring boxes 6 Explosion-proof lighting fixtures 7 Explosion-proof connections 8 Explosion-proof fans 9 Explosion-proof electrical devices with heating functions 10 Explosion-proof alarm devices 11 Explosion-proof electromagnets 12 Other explosion-proof products 13 Civilian explosion-proof products

Among explosion-proof electrical devices used in factories, the flameproof type and the increased safety type are the most commonly used; the intrinsically safe type is also used to some extent, while other types of explosion-proof electrical devices are less utilized. These products are classified as follows: 1. Explosion-proof control boxes 2. Explosion-proof starters 3. Explosion-proof control switches 4. Explosion-proof command devices 5. Explosion-proof wiring boxes 6. Explosion-proof lighting fixtures 7. Explosion-proof connectors. For more detailed information, please visit http://www.coan.cn/cn/news_disp2.asp?id=81

1 Explosion-proof control boxes 2 Explosion-proof starters 3 Explosion-proof control switches 4 Explosion-proof command devices 5 Explosion-proof wiring boxes 6 Explosion-proof lighting fixtures 7 Explosion-proof connections 8 Explosion-proof fans 9 Explosion-proof electrical devices with heating functions 10 Explosion-proof alarm devices 11 Explosion-proof electromagnets 12 Other explosion-proof products 13 Civilian explosion-proof products

Explosion-proof control boxes; explosion-proof starters; explosion-proof control switches; explosion-proof command devices; explosion-proof wiring boxes; explosion-proof lighting fixtures; explosion-proof connectors; explosion-proof fans; explosion-proof electrical devices with heating functions; explosion-proof alarm devices; explosion-proof electromagnets; other explosion-proof products

① Explosion-proof type (d) • This electrical equipment features an explosion-proof enclosure that prevents external explosive mixtures from exploding, even if an explosive mixture enters the interior and causes an explosion there. •It is designed based on the principle of the maximum non-detonation gap, and features a robust casing that can withstand 1.5 times the actual explosion pressure without deforming ； The temperature of the equipment while it is operating continuously must also not be sufficient to ignite explosive mixtures. •These devices have a high level of safety and can be used in hazardous areas at all levels other than Zone 0. ② Increased safety type (e) • Also known as explosion-proof safety type; under normal operating conditions, it does not generate sparks that could ignite explosive mixtures nor reach dangerous temperatures. It is suitable for Class 1 and Class 2 hazardous areas. ③ Intrinsically safe type (i) • Neither sparks nor heat generated under normal operation or under standard test conditions can ignite explosive mixtures. •Intrinsic safety equipment is further divided into Class ia and Class ib based on its level of safety: •Class ia – prevents the ignition of explosive gas mixtures under normal operating conditions as well as in the presence of one or two faults; it is mainly used in Zone 0 ； •Class ib – fails to ignite explosive gas mixtures under normal operation and in the presence of a fault; mainly used in Zone 1. ④ Positive pressure type (p): This type of electrical equipment has a protective enclosure filled with a protective gas (inert gas), and the pressure within this enclosure is higher than that of the explosive mixture surrounding it, thereby preventing external explosive mixtures from entering the enclosure and causing an explosion. ⑤ The oil-filled type (o) immerses components that may generate sparks, arcs, or dangerous temperatures in oil, serving to extinguish arcs, provide insulation, dissipate heat, and prevent corrosion, thereby preventing the ignition of explosive mixtures above the oil surface and around the enclosure. ⑥ Sand-filled type (q) • The enclosure is filled with fine sand particles, so that under specified operating conditions, the arc and flame generated within the enclosure, as well as the excessive temperatures on the walls of the enclosure or on the surface of the particle material, cannot ignite the surrounding explosive mixture. •Suitable for Class 1 and Class 2 hazardous areas. ⑦ Spark-free type (n) • Under normal operating conditions, it does not generate arcs or sparks, nor does it produce hot surfaces or hot spots that could ignite surrounding explosive substances; faults that could cause ignition generally do not occur. •It is mainly used in Class 2 hazardous areas and has a wide range of applications. ⑧ Explosion-proof special type (s) • Electrical equipment with explosion-proof measures that go beyond those specified in national standards; it is designed specifically for Zone 0 or Zone 1, but such equipment must be approved by the relevant authorities and pass inspection by designated testing institutions.

1 Explosion-proof control boxes 2 Explosion-proof starters 3 Explosion-proof control switches 4 Explosion-proof command devices 5 Explosion-proof wiring boxes 6 Explosion-proof lighting fixtures 7 Explosion-proof connections 8 Explosion-proof fans 9 Explosion-proof electrical devices with heating functions 10 Explosion-proof alarm devices 11 Explosion-proof electromagnets 12 Other explosion-proof products 13 Civilian explosion-proof products

Explosion-proof control boxes; explosion-proof starters; explosion-proof control switches; explosion-proof command devices; explosion-proof wiring boxes; explosion-proof lighting fixtures; explosion-proof connectors; explosion-proof fans; explosion-proof electrical devices with heating functions; explosion-proof alarm devices; explosion-proof electromagnets; other explosion-proof products

1 Explosion-proof control boxes 2 Explosion-proof starters 3 Explosion-proof control switches 4 Explosion-proof command devices 5 Explosion-proof wiring boxes 6 Explosion-proof lighting fixtures 7 Explosion-proof connections 8 Explosion-proof fans 9 Explosion-proof electrical devices with heating functions 10 Explosion-proof alarm devices 11 Explosion-proof electromagnets 12 Other explosion-proof products 13 Civilian explosion-proof products

1 Explosion-proof control boxes 　　These mainly include lighting distribution boxes used to control lighting systems, and power boxes used to control power systems. Most of these products have a modular structure and can control up to 12 circuits. Their casings are mostly made of cast aluminum alloy, some are welded from steel plates, and a very small number have casings made of insulating materials. Its interior mainly consists of circuit breakers, contactors, and thermal relays. It is composed of switches, signal lights, buttons, and other components; the manufacturer can also choose to include additional items based on the user’s requirements. The explosion protection rating can reach up to IICT6. Incidentally, explosion-proof automatic switches, explosion-proof knife switches, and fuses are also commonly used in certain control applications to open and close circuits in power or lighting distribution systems, though in this case they function as a single unit. Therefore, these products are also classified under this category. 　　2 Explosion-proof starters This category includes products such as manual starters, electromagnetic starters, reversible electromagnetic starters, autotransformer step-down starters, Y–Δ transformation step-down starters, and feed switches. As terminal control devices, explosion-proof starter products typically involve one starter controlling one motor, and they are products that are widely used in large quantities. Its outer shell is usually made of cast aluminum alloy or steel plate. Its interior generally consists of components such as contactors (air-type or vacuum-type), motor protection systems, signal lights, buttons, and autotransformers, and it usually features local control, remote control, and automatic control functions. Some products also come equipped with a circuit breaker as a main switch, making them more complete. 　　3. Explosion-proof control switches The market demand for these products is also relatively high, which is why there are many manufacturers of them. They mainly include small explosion-proof products such as lighting switches, changeover switches (combination switches), limit switches, and pull-cord switches. The explosion protection rating of these products can reach level II CT6. Their explosion-proof enclosures are usually of composite structure, made by die-casting aluminum alloys; however, a few manufacturers use enclosures made from other materials. These products are characterized by their small size, single internal components, low technical complexity, simple structure, and ease of manufacture. 　　4 Explosion-proof master control electrical apparatus Master control electrical apparatus are switching devices used to close or open control circuits in order to issue commands or carry out programmed controls. Such explosion-proof electrical devices mainly include control buttons and operation levers. The housings for explosion-proof control buttons are generally manufactured by injection molding using polycarbonate, glass fiber-reinforced unsaturated polyester resin, or ABS plastic; in some cases, they are also formed by die-casting aluminum. Its general structure features a enhanced safety enclosure containing flameproof components, and it also offers corrosion protection; its explosion protection rating can reach Class II C. The operation column mainly consists of a main box, a wiring box, and struts. Their main box and wiring box are either integrated or separate, each with its own advantages. Its material is basically made of cast aluminum alloy. The interior is composed of various components such as instruments, toggle switches, buttons, and signal lights. It can be combined according to different needs. 　　5 Explosion-proof junction boxes Electrical equipment must be connected to the power supply network through wires or cables in order to form a system that enables it to perform its functions. However, its connection wires or cables cannot be infinitely long, and there are many points during the connection process where wires need to be branched through series and parallel connections. This will inevitably lead to external leakage at the joint area, making accidents likely. Explosion-proof junction box products are designed to address such issues, in order to further ensure safe production. Such products include junction boxes, wiring boxes, conduit boxes, suspension boxes, distribution boxes, etc., whose housings are mainly made of cast aluminum alloy. As required, there are numerous inlet and outlet connection devices, and the box is equipped with terminal blocks for making connections or branching. Most of these products are manufactured as explosion-proof or increased-safety types, with varying sizes and significant differences; their explosion protection rating can reach Class II C. 　　6 Explosion-proof lighting fixtures 　 Lighting measures must be implemented in any workplace or environment, and this applies equally to places containing various explosive gases. Due to their wide range of applications in various production areas, explosion-proof lighting products are manufactured in large quantities. There are a wide variety of such products with diverse specifications, but they can generally be classified into categories such as those for lighting, signage, signaling, and portable use. In terms of light source types, they include incandescent lamps, mercury lamps, neon lamps, halogen lamps, dysprosium lamps, and fluorescent lamps. Structurally, there is an even greater variety: they can be ceiling-mounted, wall-mounted, recessed, portable, or cantilevered, among others. From an installation perspective, explosion-proof lighting fixtures can be installed at angles ranging from 30° to 90°. In terms of power, it can range from dozens of watts to several hundred watts. The installation height ranges from the ground level up to several meters. It can be said that explosion-proof lighting fixtures are the products with the highest production volume and widest use among all explosion-proof electrical products. Furthermore, due to its specific functions, it results in high wear and a high frequency of replacements. These products come in a wide variety of structural shapes, but in terms of explosion-proof performance, they are mainly of the flame-retardant type. The casing is usually made of cast aluminum alloy, and they are capable of meeting the various lighting and display requirements of users in areas classified as below Class II C. 　　7 Explosion-proof Connection Types The main function of explosion-proof connectors is to facilitate cable connections and cable branching. Its main products are explosion-proof latches and explosion-proof power socket boxes. The rated voltage ranges from 220V to 380V, and the maximum rated operating current can reach 100A. There are two-pole and three-pole versions, with neutral and ground wires. The product enclosures are available in metal or plastic materials, and the explosion protection rating can reach Class II C. Its interior is mainly composed of connectors; some products are equipped with a switch with a cut-off function, and there is a interlocking mechanism between this switch and the connectors – that is, the switch must be turned off first before the connector is plugged or pulled out, and the connector must be inserted first before the switch is turned on. Products without a switch also have the function of first disconnecting the main circuit before disconnecting the ground wire, and first inserting the ground wire before inserting the main circuit. All of this is to ensure operation in a safe condition. Most of these products are operated manually, so relatively high insulation performance is required, and this aspect must not be overlooked. 　　8 Explosion-proof fans This category of products mainly includes explosion-proof ceiling fans, explosion-proof exhaust fans, and explosion-proof axial flow fans. Their structure consists of an explosion-proof motor, an explosion-proof wiring box, an explosion-proof speed control controller, and blades. Its rated operating voltage is generally up to 380V, and its explosion protection rating can reach II BT4. 　　9 Explosion-proof electrical appliances with heating functions Petrochemical companies often need various heating devices and electrical heating systems during production; therefore, the explosion-proof characteristics of such products are also of great importance. The main products include explosion-proof electric heaters and explosion-proof heaters. Since products such as explosion-proof control transformers and explosion-proof ballasts, although their primary function is not to generate heat, still produce heat during operation, this aspect also deserves great attention; therefore, they are all classified under this category of products. Of course, in today’s era of rapid technological advancement, there are many electric heating devices made from high-tech materials, but the issue of explosion prevention still cannot be ignored. The main components of explosion-proof heating equipment include windings, controllers, and junction boxes, and it often possesses protective functions for controlling or monitoring temperature. Such products are basically flameproof, with a protection rating of II BT4. 　　10 Explosion-proof alarm electrical appliances In certain production environments, lights and sounds are often needed to guide people’s actions, and such electrical appliances become even more important in areas with explosive gases. Its main products include explosion-proof indicator lights, explosion-proof bells, explosion-proof whistles, and explosion-proof horns. The design is typically flame-retardant type, manufactured from cast aluminum alloy, with an explosion protection rating of up to IICT6. Its operating voltage can range from 36 to 220V for direct current, and up to 380V for alternating current. Explosion-proof junction boxes and explosion-proof enclosures are its main structural components. 　　11 Explosion-proof electromagnets This category of products mainly includes explosion-proof electromagnets, explosion-proof solenoid valves, and explosion-proof electromagnetic drivers. Its working principle is that, under the action of an electromagnetic field, the generated electromagnetic force is used to drive mechanical equipment, usually for braking purposes. The structure is mostly flameproof type, manufactured from cast steel or cast iron, with a flame protection rating of II BT6. Its main technical parameters are generally thrust or suction (in kg) and the duty cycle; it must not be powered on for extended periods, as this can lead to overheating and pose a risk. 　　12 Other explosion-proof categories In complex production processes, many special requirements arise, which necessitate the creation of specialized explosion-proof electrical products. Due to the low production volume of such products, their specific requirements, and the fact that they are non-standard items, they are classified under other explosion-proof categories. The main products include electrical meters, temperature transmitters, pressure transmitters, speed transmitters, level gauges, quantitative control devices, ignition systems, cameras, and other such items. These products are basically manufactured to meet production needs. Although their performance requirements vary, most of them have metal enclosures in an intrinsically safe or enhanced safety design; a small portion of them are intrinsically safe products, with generally low operating voltages and currents, and an explosion protection rating of IICT6. 　　The explosion-proof electrical products used in factories have been roughly divided into twelve major categories above, in order to achieve a clearer and more rational understanding of these products. The above classification may have omissions or be incomplete. But it basically includes most of the products available on the market today. 　　It should be noted that there are also other products, such as reducer fittings, sealing joints, pipe fittings, swivel joints, flexible connection pipes, etc.; many manufacturers classify these as explosion-proof products as well, which is a misconception. These products can only be regarded as accessories for explosion-proof electrical equipment. Therefore, the product categories here do not include these products. 　　13 Civilian explosion-proof products 　　Due to the needs in real life, there is now a demand for explosion-proof products in civilian use as well. These products are diverse in nature, so they are collectively classified as civilian explosion-proof products; examples include explosion-proof tricycles and explosion-proof electric drills. Such products require a high level of technology. It is also a new starting point and a new direction for the explosion-proof industry!