Shenzhen Zhongnuo Testing Technology Co., Ltd. is based in South China and offers on-site explosion-proof construction, safety inspections, renovations, project acceptance, and explosion-proof installation consulting services. We are well-versed in explosion-proof construction standards, boasting experienced construction teams and a wealth of practical experience. We have served major corporations such as PetroChina, LG, Hanlan Environment, BOE Technology Group, and Sinovac Biotech, receiving consistent praise and trust from our clients!
Basic Requirements for Explosion-Proof Electrical Installations in Explosive Areas (Shared by Shenzhen ZhongNuo Inspection Technology Co., Ltd.)
1. Oil-immersed equipment should be used under conditions of no vibration, no tilt, and fixed installation.
2. When using non-explosion-proof equipment for mechanical transmission in partition walls, the following regulations should be followed:
(1) Rooms housing electrical equipment should be separated from the explosion hazard area by solid walls made of non-combustible materials.
(2) Transmission shafts should be sealed with gland packing or equivalent sealing measures at the wall partition.
(3) The exit of the room housing electrical equipment should lead to an environment free from explosive hazard areas.
(4) When the room for installing the equipment must be connected to an explosive atmosphere, a positive pressure relative to the explosive atmosphere should be maintained.
3. Electrical circuits and equipment in explosive environments, excluding inherently safe circuits, should be equipped with overload, short-circuit, and grounding protection. Electrical equipment that cannot overload may not require overload protection. Motors in explosive environments, in addition to the necessary protection as required by current standards, should also be equipped with phase-loss protection. If the automatic shutdown of electrical equipment could pose a greater risk than the ignition hazard, an alarm device should be used instead of an automatic shutdown device.
4. In emergency situations, appropriate measures should be taken at a suitable location outside the hazardous area to disconnect the power to the equipment in the hazardous area. 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, etc.), and control rooms should be located outside of explosive atmosphere environments. When they are in positive pressure rooms, they can be arranged in Zones 1 and 2.
(2) In explosive gas atmospheres where the gas is heavier than air, the equipment floor of electrical and instrumentation equipment in substations, distribution stations, and control rooms located in the additional zone 2 of the explosion hazard area should be elevated 0.6 meters above the exterior ground level.

Shenzhen ZhongNuo Testing Technology Co., Ltd. offers explosion-proof construction services for hazardous areas involving explosive risks.
1. Explosion-proof site inspection and consultation
2. Explosion-proof construction and renovation on-site
3. Explosion-proof construction acceptance
4. Explosion-proof electrical installation, maintenance, and renovation
5. Explosion relief walls, doors, and windows installation
6. Dust Removal Equipment Installation and Renovation Construction

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 critical. This includes explosion-proof wiring, the installation and use of explosion-proof electrical equipment, dust extraction systems, building structural layout, and explosion-proof venting, all of which must comply with the relevant dust explosion-proof standards. Based on a wealth of explosion-proof electrical installation and retrofitting cases, Shenzhen ZhongNuo Testing Technology Co., Ltd. has summarized the following points:
4. Explosion-proof electrical equipment
Electrical equipment used in dust explosion hazard areas must comply with the relevant standards of GB/T3836. The power design should be executed in accordance with the provisions of GB50058. Explosion-proof electrical equipment should be selected based on the grade of the explosion hazard area, the category, grade, and group of the explosive hazardous substances.
Options for explosion-proof electrical equipment. Dust explosion-proof electrical equipment with dust-tight structures are used in explosive dust environments, such as Zone 20 in the 20 area and Zone 21 in other explosive dust environments, in addition to the 21 area environment with combustible non-conductive dust and combustible fibers, which utilizes dust-proof electrical equipment with dust-proof structures. Different electrical equipment with varying ignition temperatures are selected based on the different ignition temperatures of the dust.
(2) Galvanized焊接 steel pipes for low-pressure fluid conveyance
(3) Connections between steel pipes, steel pipes and electrical equipment, and steel pipe accessories should be made using threaded connections. Soldering with sleeves is prohibited, and the following requirements must be met: the threading should be smooth, complete, and free of rust. Electrical compound grease or conductive anti-rust grease should be applied to the threads. Do not wrap the threads with hemp or insulating tape, nor apply other paints. For steel pipes with a diameter of 25mm or less, there should be at least 5 threads. For steel pipes with a diameter of 32mm or more, there should be at least 6 threads.
(4) Flexible anti-explosion conduit should be installed at the following locations for pipeline wiring of steel pipes: at the motor's entry clamp, where direct connection of steel pipes to electrical equipment is difficult, and where pipelines pass through the expansion joints and settlement joints of buildings.
(5) Mobile electrical equipment is not recommended in Zones 20, 21, and 22. If mobile electrical equipment must be used, YC or YCW rubber cables should be selected for the wiring.
AQ3009-2007 "Electrical Explosion Protection Safety Code for Hazardous Areas" classifies dust explosion areas into 20 zones, 21 zones, and 22 zones.
5. Ventilation and Dust Removal
(1) Preferably, the dust removal system should be set up in a relatively opposing manner according to the process sections.
(2) All dust-generating points should be equipped with dust extraction hoods.
(3) There should be no dust accumulation in the ductwork.
(4) Bag dust collectors should be used, with external filtration type being given priority.
(5) Dust collectors should be installed outdoors. If installed indoors, their explosion relief pipes should directly lead outside, with a length less than 3 meters, and a explosion-proof device should be set up based on the dust properties.
(6) It is advisable to install isolation valves at the inlet and outlet of the dust collector and set up a temperature monitoring device.
(7) Pulse-jet bag dust collector should use nitrogen, carbon dioxide, or other inert gases as the cleaning gas source.
6. Fire Protection
(1) Select the appropriate fire extinguisher based on the physical and chemical properties of the dust.
(2) During extinguishing, prevent dust from being raised to form a dust cloud.
(3) If a combustible material generates explosive gases when in contact with water, do not use water to extinguish the fire.
7. Job Safety
When dust clouds can be ignited by sparks caused by collisions, measures should be taken to prevent collisions from occurring. Additionally, explosion-proof tools should be used during maintenance.
(2) Do not use rotating grinding wheels and rotating cutting disks for grinding and cutting without equivalent protection measures to those for open flame operations.
(3) All production workshops and storage rooms where dust may accumulate should be cleaned promptly.
(4) No compressed air should be used for井下吹扫.
(5) At the workplace, production personnel should not wear synthetic fiber garments or pants next to their skin.

Installation of electrical lines in explosive environment should comply with the following regulations (Shared by Shenzhen ZhongNuo Inspection Technology Co., Ltd.)
Electrical wiring should be installed in environments with low explosion hazards or far from the source of release, and it should comply with the following regulations:
1) When the weight of the material is heavier than air, electrical lines should be laid at a higher position or directly buried underground; for overhead installation, cable trays should be used; when laying in a cable trench, sand should be filled in the trench, and drainage measures should be in place.
2) Electrical wiring should be laid outside the walls of buildings or structures where there is a risk of explosion.
3) In explosive dust environments, cables should be laid in areas where dust is less likely to accumulate and is easy to dust off.
(2) Holes in walls or floors at different areas traversed by electrical line trenches, cable trays, or conduits should be tightly sealed with non-combustible materials.
(3) When laying electrical wiring, it is advisable to avoid areas susceptible to mechanical damage, vibration, corrosion, ultraviolet radiation, and heat exposure. If avoidance is not possible, preventive measures should be taken.
(4) Conduit wiring can use insulated single-core or multi-core wires without sheath. When the conduit contains three or more wires, the total cross-sectional area of the wires, including the insulation, should not exceed 40% of the conduit's cross-sectional area. The conduit should be made of galvanized steel焊接 pipes for low-pressure fluid conveyance. The threaded portion of the steel conduit should be coated with lead oil or phosphating paste. In areas where condensation water may form, a sealed joint for draining condensation water should be installed on the conduit.
(5) Electrical wiring for pipe routing in explosive gas environments should be properly insulated and sealed, and should comply with the following regulations:
1) During normal operation, all ignition source enclosures within a 450mm radius should be sealed off with insulation.
2) Steel pipes with a diameter of 50mm or more should be isolated and sealed within 450mm from 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. When sealing, the inner surface of the seal should be lined with a fibrous layer as the base or separator, with an effective thickness not less than the inner diameter of the steel pipe and not less than 16mm.
4) Connection parts for isolation sealing 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 ends of cables or wires, if the internal wires are stranded, the ends should be connected using a molded terminal or a crimped connector. The connection and termination of aluminum-core insulated wires or cables should be done by crimping, soldering, or brazing. When connecting to equipment (excluding lighting fixtures), a copper-aluminum transition connector should be used.
(8) Overhead power lines shall 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. Under special circumstances, the distance may be appropriately reduced after effective measures are taken.
explosion-proof electrical modification for hazardous areas and site explosion-proof construction consultation services - Shenzhen ZhongNuo Inspection Technology Co., Ltd.