What are the explosion protection types listed on the explosion protection certificate?

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This post was last edited by Zhongnuo Service Window 08 on 2020-11-5 09:47. I. Flameproof electrical equipment – “d” flameproof enclosure: capable of withstanding the explosive pressure of explosive gas mixtures inside, and preventing the explosion from spreading from within the enclosure to the explosive mixtures surrounding it. A robust enclosure is created for electrical equipment, with gaps at all seams being smaller than the maximum safe gap required for the corresponding flammable gases. If flammable gases enter the enclosure and are ignited by a spark, causing an explosion, the flames of that explosion are contained within the enclosure and cannot ignite explosive mixtures in the environment outside it, thereby ensuring safety in the surrounding area. (1) The flameproof enclosure must meet two basic conditions: 1. The enclosure must have sufficient mechanical strength to withstand the internal explosion pressure without being damaged or suffering from permanent deformation that could affect its flameproof properties. 2. All seams and gaps on the enclosure walls that are in contact with the outside environment must be smaller than the corresponding maximum allowable safety gaps. (2) Main flameproofing measures: 1. Requirements regarding the material of the flameproof enclosure; 2. Requirements regarding the gap length and width, as well as the surface finish of the flameproof joints; 3. Requirements for fasteners and the threads used for fastening; 4. Requirements for transparent components; 5. Requirements for adhesives and sealants; 6. Grounding; 7. Devices for introducing cables and conduits; 8. Interlocks or warning signs, etc. (3) Standards referred to for the flameproof design of flameproof electrical products: GB3836.2-2010 “Non-electrical equipment for explosive atmospheres – Part 2: Equipment protected by flameproof enclosures of type ‘d’”. II. Positive-pressure electrical equipment of type “p”: In this type of equipment, fresh air or an inert gas is introduced into the enclosure at a certain pressure, thereby preventing flammable gases from entering the enclosure. This prevents ignition sources from coming into contact with explosive gases, thus achieving flameproofing. (1) Key explosion-proof measures for positive-pressure electrical equipment: 1. The pressure of the protective gas (fresh air or inert gas) inside the equipment enclosure must be at least 50 Pa higher than the ambient pressure. 2. Before the electrical equipment is powered on, the enclosure should be flushed with protective gas (usually an amount of gas equal to 5 times the net volume of the enclosure). Therefore, the equipment requires components such as blowers, pipes, and pressure relays; this approach is typically used for large motors and control switchgear. (2) Standards referenced for the explosion-proof design of positive-pressure electrical products: GB-T3836.5-2017 “Non-electrical equipment for explosive atmospheres – Part 5: Equipment protected by positive-pressure enclosures”. 3. Oil-immersed electrical equipment: The entire or part of the equipment is immersed in oil within the enclosure, thereby preventing explosive gases above the oil surface or outside the enclosure from igniting. (1) Main explosion-proof measures: 1. Submerge the live components at least 25 mm below the oil surface. 2. The oil should be transformer oil that meets the standards specified in GB2536. 3. The oil temperature must not exceed 100°C. 4. An oil level indicator should be installed. 5. Insulation materials and sealing materials must be oil-resistant. 6. The maximum switching capacity of the equipment shall be 75% of the safe value determined by ignition tests. This type of explosion protection is mainly used for transformers and high-voltage switches. (2) Standards referred to for the explosion-proof design of oil-filled electrical equipment: GB3836.6-2004 “Electrical equipment for explosive gas environments – Part 6: Oil-immersed ‘o’ devices”. 4. Sand-filled electrical equipment “q”: The enclosure is filled with sand, so that under specified operating conditions, arcs and flames generated within the enclosure, as well as the surfaces of the enclosure walls and the sand, cannot ignite the surrounding explosive mixture. (I) Main explosion-proof measures: 1. The enclosure is filled with sand-like material and has a sufficient safety height. 2. The particle size of the quartz sand ranges from 0.25 to 1.6 mm, with a moisture content of no more than 0.1%. 3. Electrical clearance is provided. 4. There is a specified protection rating for the enclosure. This type of explosion protection is mainly suitable for products such as fuses and capacitors. (II) Standards referenced for the explosion-proof design of sand-filled electrical equipment: GB3836.7-2004 “Electrical equipment for explosive gas environments – Part 7: Sand-filled type ‘q’”.

V. Encased electrical equipment of type “m”: The parts of the equipment that may generate sparks or high temperatures are encased in an encapsulating agent (resin), thereby preventing them from igniting the surrounding explosive mixtures. (I) Main explosion-proof measures: 1. The electrical components are enclosed using resin; the free surface of the encapsulating agent and the thickness of the encapsulation around the components or conductors must be at least 3 mm. 2. There are specifications regarding the dielectric strength, water absorption, resistance to light, heat, and cold, as well as the surface resistance of the encapsulating agent. 3. Surface temperature limits are also specified. (II) Standards referenced for the explosion-proof design of encased electrical equipment: GB3836.9-2014 “Electrical equipment for explosive gas environments – Part 9: Equipment protected by encasing type ‘m’”.

VI. Intrinsically safe electrical equipment of type “i”: Under specified test conditions, neither the electrical sparks nor the thermal effects generated when the equipment operates normally nor under specified fault conditions can ignite the specified explosive mixtures. The main explosion-proof measure for intrinsically safe systems is to limit the energy in the circuit, ensuring that the energy of any sparks generated is less than the corresponding minimum ignition energy. (1) Main explosion-proof measures: 1. Voltage and current limits for circuits; 2. Limits on capacitance and inductance in circuits; 3. Isolation between intrinsically safe circuits and non-intrinsically safe circuits; 4. Requirements for reliable components and assemblies; 5. Regulations regarding safety barriers; 6. Provisions for fault analysis and testing, etc. Applicable products: Low-voltage equipment such as measuring, control, and communication devices. (2) Standards referred to for the explosion-proof design of intrinsically safe electrical equipment: GB3836.4-2010 “Electrical equipment for explosive gas environments – Part 4: Equipment protected by intrinsically safe ‘i’ design”. VII. “e”-type enhanced safety electrical equipment: Electrical equipment whose structure includes measures to improve safety levels, so as to prevent the occurrence of sparks, arcs, or conditions that could ignite explosive mixtures under normal operating conditions as well as under acceptable overload conditions (including motor stall conditions). (1) Increased-safety electrical equipment does not have an explosion-proof enclosure or protective medium; instead, it relies on comprehensive safety measures: 1) limiting the types of equipment used, 2) ensuring sufficient electrical clearance and creepage distance, 3) using high-quality insulating materials, 4) specifying proper methods for connecting conductors, 5) reducing temperature rise, 6) increasing the protection rating of the enclosure, 7) using appropriate protective devices, etc. Products that fall under this category include asynchronous motors, transformers, junction boxes, etc. (2) The standard referred to for the explosion-proof design of increased-safety electrical equipment is GB3836.3-2010 “Electrical equipment for explosive gas environments – Part 3: Increased-safety electrical equipment”.

VIII. Spark-free electrical equipment: This is a type of explosion-proof electrical equipment that cannot ignite the surrounding explosive environment during normal operation or under certain conditions specified in this standard (only in the case of failures in the light source of lamps). Initially, spark-free equipment referred to those that did not generate sparks or arcs during normal operation, such as AC asynchronous motors. Additional safety measures are taken for such equipment, including using spark-free materials for fan blades, assigning an enclosure protection rating of IP44 or IP54, and ensuring adequate electrical clearance and creepage distance. Later, this concept of explosion protection was extended to electrical products that generate sparks during normal operation; measures such as gas sealing, simple ventilation, or energy limitation were taken depending on the specific situation, in order to achieve a certain level of safety. Due to this expansion of explosion-proof types, the term “spark-free” is no longer very accurate; it is now often referred to as type “n”. (1) N-type devices can be divided into two categories: 1. Devices that do not generate sparks or arcs during normal operation, such as asynchronous motors, transformers, lighting fixtures, and junction boxes. 2. Devices such as plug-in connectors that generate sparks or arcs during normal operation, such as switches and relays. (II) Standards for the explosion-proof design of n-type electrical equipment: GB3836.8-2014 \"Electrical equipment for explosive gas environments – Part 8: n-type electrical equipment\"