Shenzhen ZhongNuo Testing Technology Co., Ltd. is based in South China, offering explosion-proof construction, safety inspections, renovations, project acceptance, and installation 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, Huanlan Environment, BOE Technology Group, and Sinovac Biotech, receiving consistent praise and trust from our clients!
Protection of explosive loop circuits should comply with the following regulations (shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
In the single-phase network within Zone 1, both the phase lines and neutral lines should be equipped with short-circuit protection, and appropriate switches should be used to simultaneously disconnect both the phase lines and neutral lines.
(2) For 3kV-10kV cable lines, it is advisable to install a zero-sequence current protection, with the protective devices in Zone 1 and Zone 21 to operate by tripping.

Equipment grounding in explosive environments shall comply with the following regulations (Shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
According to the relevant provisions of the current standard "Code for Design of Grounding of AC Electrical Installations" GB/T50065, the following parts that do not require grounding should still be grounded in explosive environments:
1) Equipment with a normal non-electrified metal enclosure, where the alternating current rated voltage is below 1000V and the direct current rated voltage is below 1500V, on poor conductive ground surfaces.
2) In dry conditions, equipment with alternating current rated voltage of 127V or less and direct current voltage of 110V or less typically has metal enclosures that are not charged.
3) Equipment installed on a grounded metal structure.
(2) In explosive hazardous environments, the exposed, conductive parts of equipment should be reliably grounded. All equipment in explosive zones 0, 20, and 21, as well as other equipment in zones 2 and 22 except for lighting fixtures, should use dedicated grounding wires. If these grounding wires are installed in the same protective conduit as the phase wires, they should have insulation equal to that of the phase wires. Lighting fixtures in zones 2 and 22 may utilize a metal piping system with reliable electrical connections as a grounding wire, but not pipes used for conveying substances.
(3) In different directions on the slope of the explosion hazard area, the grounding main should be connected to the grounding body at least twice.

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 on-site explosion-proof measures is particularly important. The installation and use of explosion-proof electrical systems, dust removal systems, structural layouts, and explosion-proof and venting measures must all 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:
4. Explosion-proof electrical equipment
Electrical equipment used in dust explosion hazard areas shall 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 and the category, level, and group of the explosive hazardous substances.
Options for explosion-proof electrical equipment. In addition to dust explosion-proof electrical equipment with dust-tight construction for the 21-zone environment containing combustible non-conductive dust and combustible fibers, dust explosion-proof electrical equipment with dust-tight construction is used in the 20-zone explosion-proof dust environment and other 21-zone explosion-proof dust environments. The electrical equipment is selected based on different ignition temperature groups according to the varying ignition temperatures of the dust.
(2) Low-pressure fluid conveyance galvanized welded steel pipes for conduit piping
(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 grease or conductive anti-rust grease should be applied to the threads. Do not wrap 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, and for pipes with a diameter of 32mm or more, there should be at least 6 threads.
(4) Flexible explosion-proof conduits should be installed at the following locations for pipe wiring: at the motor's incoming line clamp, where it is difficult to directly connect the steel pipe with electrical equipment, and where the pipeline passes through the expansion joints or settlement joints in the building.
(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" categorizes dust explosion prone areas into 20 zones, 21 zones, and 22 zones.
5. Ventilation and dust removal
(1) Dust removal systems should be set up in opposition, categorized by process sections.
All dust-generating points should be equipped with dust collectors.
(3) There should be no dust sedimentation in the ductwork.
(4) Baghouse dust collectors should be used, with the preference for external filter type.
(5) Dust collectors should be installed outdoors. If installed indoors, their explosion relief pipes should be directly connected to the outside, with a length less than 3 meters, and a flame arrester should be installed based on the dust properties.
(6) It is advisable to install isolation valves at the inlet and outlet of the dust collector, and to 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.
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 combustible materials generate explosive gases upon contact with water, do not use water to extinguish the fire.
7. Job Safety
When dust clouds can be ignited by sparks produced 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.
All production workshops and storage rooms where dust may accumulate should be cleaned promptly.
(4) Do not use compressed air for downhole blowing.
(5) At the workplace, production personnel should not wear synthetic fiber garments next to their skin.

In the design of industrial factory buildings, different production processes have varying requirements for the structures. Production facilities for precision instruments and equipment demand constant temperature, humidity, and cleanliness; while certain hot workshops and dust-laden areas require adequate ventilation and dust removal systems. For industrial enterprises such as chemical, pharmaceutical, and petrochemical industries, due to the risk of explosion during the production process, it is essential to seriously consider explosion prevention in the design of the factory buildings, in addition to meeting the production process requirements. In the event of an explosion, efforts should be made to minimize the loss of life and property. Shenzhen Zhongnuo Testing Technology Co., Ltd. shares its views on the design of buildings for explosive areas and electrical wiring, for your reference only.
Basic explosion-proof technical measures in factory building design
(1) For factories (such as plants) with explosive hazards throughout the entire industrial area, the overall planning and design should consider factors like the production processes, product types, production characteristics, and degree of danger of hazardous materials within the buildings. After determining the danger level of the buildings, zoning planning should be carried out. The distances between buildings within the hazardous material production area and surrounding villages, highways, railways, towns, and the factory's living facilities should be calculated based on the danger level of the buildings and the amount of stored chemicals, and the larger value should be taken according to standard requirements. If the required distances cannot be met due to factory site limitations, protective barriers must be installed, such as protective embankments or reinforced concrete walls. Protective barriers must be set for Class A buildings. The layout should be tailored to the actual conditions and terrain, making the most of the local geography for optimal and reasonable placement.
(2) For factory buildings and workshops within general industrial zones that produce and use products, they should be as centrally located as possible within the same area. The distance between these buildings and general workshops should meet safety requirements, facilitating unified handling of firewalls and other explosion-proof structural elements.
(3) Workshops with explosive hazards should be located in single-story buildings. If the workshop needs to be multi-story due to process requirements, it should be situated on the upper floor.
(4) When local explosion-proof rooms are installed in general factory buildings or workshops, these rooms should be as close to the exterior wall as possible. Special windows that are easy to open outward should be used, making it easier to address the venting area and facilitate fire extinguishing.
(5) Within the factory, workshops with high and low risks should be separated by sturdy fire-resistant walls (brick or reinforced concrete walls). It is advisable to open doors on the exterior walls for inter-workshop communication using corridors or balconies; or create a double-door vestibule on the fire-resistant wall, aiming to stagger the doors as much as possible to mitigate the impact of explosion shock waves and reduce the scope of the explosion's effects.
(6) For equipment prone to explosion, it should be placed as close to the exterior wall or windows as possible, or outdoors, to minimize its destructive force.
(7) Production and storage of different types of hazardous materials should be separated, such as those that must be kept apart from oxygen.
(8) Avoid locating areas with explosive hazards in basements or semi-basements, as poor ventilation can greatly impact incidents, and it is not conducive to evacuation and rescue operations.
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