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Basic Requirements for Explosion-Proof Electrical Installations in Explosive Areas (Shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
1. Oil-immersed equipment should be used under conditions of no vibration, no inclination, and fixed installation.
2. When using non-explosion-proof equipment for mechanical transmission in partition walls, the following regulations should be followed:
The room housing electrical equipment should be separated from the explosive hazard area by a solid wall made of non-combustible materials.
(2) Transmission shafts should be sealed at the wall partition with gland packing or an equivalent sealing method.
(3) The exit of the electrical equipment room should lead to an environment free of explosive hazards.
(4) When the room for installing equipment must be connected to an explosive environment, maintain a positive pressure relative to the explosive environment.
3. Electrical circuits and equipment in explosive environments, excluding intrinsic safety circuits, should be equipped with overcurrent, short-circuit, and grounding protection. Electrical equipment that cannot be overloaded need not have overcurrent protection. Motors in explosive environments should be equipped with phase-loss protection in addition to the necessary protections as required by current standards. If the automatic shutdown of electrical equipment could pose a greater danger than the risk of ignition, an alarm device should be used instead of an automatic shutdown device.
4. In emergency situations, appropriate measures should be taken at suitable locations outside of hazardous areas to disconnect power from the equipment within those areas. Continuous operating equipment should not be included in the emergency shutdown circuit and should be installed on a separate circuit to prevent the occurrence of additional hazards.
5. The design of substation, distribution substation, and control room shall comply with the following regulations:
Transformer stations, distribution stations (including distribution rooms, hereinafter referred to as such), and control rooms should be located outside of explosive atmosphere environments. When they are in a positive pressure room, they can be arranged within Zones 1 and 2.
(2) For explosive gas atmospheres where the gas is heavier than air, the electrical and instrumentation equipment floors in transformer stations, sub-stations, and control rooms located in the additional zone 2 of the explosion hazard area should be elevated 0.6 meters above the external ground level.

Basic Dust Explosion Proof Construction Standards
In facilities where explosive dust is present, such as flour mills, feed factories, grinding workshops, and plastic production plants, the requirement for explosion-proof measures on-site is particularly crucial. This includes the installation and use of explosion-proof electrical systems, dust removal systems, structural layout, and explosion-proof and deflagration venting, all of which must comply with relevant dust explosion-proof standards. Based on a wealth of explosion-proof electrical construction and retrofitting cases, Shenzhen Zhongnuo Testing Technology Co., Ltd. has summarized the following points:
Building structure and layout
Process equipment with dust explosion hazards or buildings (structures) with combustible dust should be separated from other buildings (structures), and their fire protection distances should comply with the relevant provisions of GB50016.
(2) The building should be a single-story structure, with a lightweight roof design preferred.
(3) The structural requirements for multi-story buildings are as follows:
A. Multi-story buildings are best suited for frame structures.
B. Buildings that cannot use a frame structure should be equipped with explosion relief openings in the walls that meet the required specifications.
C. If windows or other openings are used as blast relief ports, they must be calculated and ensured to effectively release blast during an explosion.
(4) Requirements for evacuation routes are as follows:
A. The work area should have an evacuation route, and the number and location of the evacuation routes should comply with the relevant provisions of GB50016.
B. The door should open outward and no threshold should be installed.
C. Detailed road signs and emergency lighting should be set up for evacuation routes.
2. Process Equipment
If the process equipment in the factory has a dust explosion hazard, it should be located on a higher floor of the building and near the outer wall.
(2) Equipment with explosive hazards should be located in outdoor open areas outside of buildings.
(3) Equipment or devices that come into direct contact with dust (such as light sources, heating sources, etc.) should have surface temperatures below the respective dust's low ignition temperature.
(4) In areas where combustible dust is present, the transmission mechanisms of the equipment and installations must comply with the following regulations:
A. The bearings of the process equipment should be dust-proof sealed, and if overheating is possible, a detector capable of continuously monitoring the bearing temperature should be installed.
B. Belt drive is not recommended. If belt drive is used, a speed difference sensor and an automatic anti-skid protection device should be installed. In case of sliding friction, the protection device should ensure automatic shutdown.
(5) At the feed point of the process, magnets, pneumatic separators, or sieves capable of removing impurities mixed with the material should be installed to prevent collisions between debris and equipment.
(6) Effective measures should be taken to prevent sparks from being generated when stainless steel is abraded with metal powders such as aluminum, zirconium, or powders containing these metals.
(7) In the event of an explosion, protective stopping should be achieved by installing several power supply control boxes that can interlock with each other, based on the size of the workshop. In emergency situations, the power supply to all motors should be able to be cut off promptly.
(8) All connections, inspection doors, baffles, and explosion relief cover for process equipment should be tightly sealed
(9) The equipment housing should be made of non-flammable material
(10) The moving parts of the equipment should operate smoothly without any scraping, bumping, jamming, or rubbing.
(11) When the strength of the process equipment is insufficient to withstand the overpressure generated by internal dust explosion under its actual operating conditions, explosion relief ports should be installed, and the size of these ports should comply with the relevant provisions of GB/T15605.
(12) The venting port should be located near the potential source of explosion, and it should be as close to the top or upper part of the containment structure as possible. It must not vent towards flammable and explosive hazard areas to prevent ignition of others, and it must not vent towards public areas to avoid causing injury from venting explosions.
3. Lightning and Static Electricity Protection
Hazardous dust explosion areas should implement lightning protection measures in accordance with the relevant provisions of GB50057. When static electricity hazards are present, the following regulations should be adhered to:
(1) All metal equipment, enclosures, metal pipes, brackets, components, and parts, generally adopt anti-static direct grounding. For those that are not convenient or not allowed by the process to be directly grounded, indirect grounding can be achieved through conductive materials or products.
(2) Equipment directly used for containing electrostatic powder, as well as conveyance pipelines (belts) for transporting powder, should be made of metal or anti-static materials.
(3) All metal pipe connections should be bonded together.
(4) Operators should take anti-static precautions.
(5) Do not use the method of contacting a directly grounded metal conductor or mesh with high-speed flowing powder to dissipate static electricity.

Installation of electrical wiring in explosive atmosphere environments shall comply with the following regulations (Shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
(1) Electrical wiring should be installed in environments with low explosion hazard or far from the source of release, and should comply with the following regulations:
1) When the weight is heavier than air, electrical lines should be laid at a higher level or directly buried. For overhead installation, cable trays should be used; for trench laying, sand should be filled in the trench, and drainage measures should be provided.
2) Electrical wiring should be laid outside the walls of buildings or structures where explosive hazards are present.
3) In explosive dust environments, cables should be laid in locations where dust does not accumulate easily and is easy to remove.
(2) Holes in walls or floors between different areas traversed by electrical line trenches, cable trays, or conduits should be tightly sealed with non-combustible materials.
(3) When laying electrical lines, it is advisable to avoid areas susceptible to mechanical damage, vibration, corrosion, UV radiation, and those that may overheat. If avoidance is not possible, preventive measures should be taken.
(4) Steel pipe wiring can use insulated single-core or multi-core wires without sheath. When the steel pipe contains three or more wires, the total cross-sectional area of the wires, including the insulation, should not exceed 40% of the steel pipe's cross-sectional area. The steel pipe should be a galvanized焊接 steel pipe used for low-pressure fluid transmission. The threaded section of the steel pipe connection should be coated with lead oil or phosphating paste. A sealed joint for draining condensate should be installed on the pipeline in places where condensation may occur.
(5) Electrical wiring for steel piping in explosive gas environments should be properly insulated and sealed, and should comply with the following regulations:
During normal operation, the 450mm radius around all ignition source enclosures should be sealed off.
2) Steel pipes with a diameter of 50mm or more should be isolated and sealed within 450mm of the incoming junction box.
3) Isolation and sealing should be carried out between adjacent explosive environments, as well as between explosive environments and adjacent other hazardous or non-hazardous environments. During sealing, the inner part of the seal should be filled with a fiber layer or separator, with the effective thickness of the filling not less than the inner diameter of the steel pipe, and not less than 16mm.
4) Components for isolation seals should not be used for wire connections or branching.
(6) Intermediate joints are strictly prohibited in cable lines within Zone 1, and intermediate joints should not be present in Zones 2, 20, and 21.
(7) When connecting the terminals of cables or wires, if the internal conductors are braided, the terminals should be connected with molded terminals or lug connectors. The connection and termination of aluminum-core insulated conductors or cables should be by crimping, soldering, or brazing. When connecting to equipment (excluding lighting fixtures), a copper-aluminum transition connector should be used.
(8) Overhead power lines must not cross explosive gas environments. The horizontal distance between overhead lines and explosive gas environments should not be less than 1.1 times the height of the tower. In special cases, after taking effective measures, the distance may be appropriately reduced.

Basic Knowledge and Requirements for Cable Use in Explosive Construction Sites (Shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
Installation methods for electrical wiring in explosive gas environments can be divided into cable wiring and conduit wiring methods.
Note: The installation of inherently safe circuits does not have to comply with the provisions of this article.
7.1 General Provisions
7.2 Electrical wiring should be installed in areas with lower explosion hazards or at a greater distance from the source of release, avoiding locations prone to mechanical damage, vibration, corrosion, dust accumulation, and those with dangerous temperatures. When avoidance is not possible, preventive measures should be taken.
7.3 The selected low-voltage cables or insulated conductors must have a rated voltage higher than the operating voltage of the circuit and not less than 500V. Insulated conductors must be installed within conduits.
7.4 No overhead lines of 10kV or less shall cross explosive gas environments; the horizontal distance between the overhead lines and the explosive gas environment shall not be less than 1.1 times the height of the pole tower.
7.5 Cables and their accessories should be installed in a location that, based on actual conditions, prevents damage from external mechanical forces, corrosion, or chemical influences (such as solvent effects), as well as the effects of high temperatures (also see 6.1.2.4.4 for this safety circuit). If such conditions cannot be avoided, protective measures should be taken during installation, such as using conduits or selecting the cable type (armored cables, shielded wires, seamless aluminum sheathed cables, mineral insulated metal sheathed cables, or semi-rigid sheathed cables, etc., to minimize damage).
7.6 Solid-core wire without a sheath should not be used for conductive wiring unless it is installed within a distribution board, enclosure, or conduit system.
Explosion-proof electrical改造 for hazardous areas and on-site explosion-proof construction consulting services - Shenzhen ZhongNuo Testing Technology Co., Ltd.