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In the design of industrial factory buildings, different production processes have varying requirements for the structures. Precision instrument and equipment production facilities require constant temperature, humidity, and cleanliness; while certain hot workshops and dust-laden workshops demand good ventilation and dust removal systems. For industrial enterprises such as chemical, pharmaceutical, and petrochemical industries, due to the risk of explosion during production, the design of the factory buildings must not only meet the production process requirements but also carefully consider explosion prevention measures. 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 systems, for your reference only.
Basic explosion-proof technical measures in factory building design
(1) For factories (such as factories) with explosive hazards throughout the entire plant area, the overall planning and design should take into account factors such as the production processes, product types, production characteristics, and degree of danger of hazardous materials within the buildings. After determining the hazard level of the buildings, zoning planning should be conducted. The distance between buildings in the hazardous material production area and surrounding villages, highways, railways, towns, and the factory's living facilities should be calculated based on the building's hazard level and the amount of stored drugs, and the greater value should be adopted according to regulatory requirements. When the required distances cannot be met due to factory site limitations, protective barriers must be established, such as protective levees or reinforced concrete walls. Protective barriers must be set for Class A buildings. The layout should be tailored to the specific conditions, making the best use of the terrain and地貌 to achieve an optimal arrangement.
(2) For production and storage facilities within general industrial zones, it is advisable to locate them in the same area as much as possible. The distance between these facilities and general workshops should meet safety requirements, facilitating the unified management of fire-resistant and explosion-proof structures like fire walls.
(3) Workshops with explosive hazards should be located in single-story buildings. If multi-story buildings are required due to process needs, they should be placed on the upper floor.
(4) When a local explosion-proof room is installed in general factory buildings or workshops, it should be as close to the exterior wall as possible. Use specially designed windows that are easy to open outward, which makes it easier to address the venting area and facilitates fire extinguishing.
(5) Within the factory, high-risk workshops and low-risk workshops should be separated by sturdy firewalls (brick or reinforced concrete walls). It is advisable to open doors on the exterior walls to facilitate communication between workshops using corridors or balconies; or create a double-door vestibule on the firewall, attempting to stagger the doors as much as possible to mitigate the force of the explosion shock wave and reduce the scope of the explosion's impact.
(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 hazardous materials of different natures should be separated, such as those that must be kept apart from oxygen.
(8) Do not locate areas with explosive hazards in basements or semi-basements due to poor ventilation, which can cause significant impact in case of an accident and hinder evacuation and rescue efforts.

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. The installation and use of explosion-proof wiring, electrical equipment, dust removal systems, architectural layout, and explosion-proof venting must all comply with the 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 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 and the category, level, and group of the explosive hazardous substances.
Options for explosion-proof electrical equipment. Dust explosion-proof electrical equipment with dust-tight structure is used in explosive dust environments, such as Zone 20, and other explosive dust environments in Zone 21. Additionally, electrical equipment with different ignition temperature groups is selected based on the different ignition temperatures of the dust.
(2) Galvanized Welded Steel Pipe for Low-Pressure Fluid Conveyance
(3) Connections between steel pipes, between steel pipes and electrical equipment, and between steel pipe accessories should be made with threaded connections. Soldering with sleeve pipes is not permitted and the following requirements must be met: threading should be smooth, complete, and free from rust. A power compound grease or conductive rust preventative should be applied to the threads. Do not wrap hemp or insulating tape around the threads, 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 explosion-proof conduits should be installed at the following locations: at the motor's entry terminal, where direct connection between the steel pipe and electrical equipment is difficult, and at the expansion joints and settlement joints of the piping through the building.
(5) Mobile electrical equipment should not be used in Zones 20, 21, and 22. If the use of mobile electrical equipment is necessary, YC or YCW rubber cables should be selected for the wiring.
AQ3009-2007 "Electrical Explosion Protection Safety Regulations for Hazardous Areas" classifies dust explosion hazard areas into 20 zones, 21 zones, and 22 zones.
5. Ventilation and Dust Removal
(1) The dust removal system should be set up in opposing sections according to the process.
(2) All dust-generating points should be equipped with dust collection hoods.
(3) There should be no dust settling in the ductwork.
(4) Baghouse dust collectors should be used, with preference given to the external filtration type.
(5) Dust collectors should be installed outdoors. If installed indoors, the explosion relief pipe should directly lead to the 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, along with temperature monitoring devices.
(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 fire extinguishing, prevent the dust from rising to form a dust cloud.
(3) If a combustible material reacts with water to produce explosive gases, do not use water to extinguish the fire.
7. Job Safety
When dust clouds can be ignited by sparks produced from collisions, measures should be taken to prevent collisions, and at the same time, explosion-proof tools should be used during maintenance.
(2) Do not use rotating grinding wheels and rotating cutting disks for grinding and cutting if there are no equivalent protective measures to firework operations.
(3) All production workshops and storage rooms where dust may accumulate should be cleaned promptly.
(4) Compressed air underground blowing should not be used.
(5) In the workplace, production personnel should not wear synthetic fiber garments that are worn next to the skin.

Equipment grounding in explosive environments shall comply with the following specifications (shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
In accordance with the relevant provisions of the current standard "Code for Grounding Design of AC Electrical Installations" GB/T50065, the following parts that do not require grounding should still be grounded in explosive environments:
1) Non-conductive surfaces: metal enclosures of equipment with an alternating current rated voltage of less than 1000V and a direct current rated voltage of less than 1500V, which are normally not energized.
2) In dry environments, equipment with alternating voltage of 127V or less and direct voltage of 110V or less typically has a non-electrified metal housing.
3) Equipment installed on a grounded metal structure.
(2) In explosive hazardous environments, the exposed conductive parts of the equipment should be reliably grounded. All equipment within explosive zones 0, 20, and 21, as well as other equipment in zones 2 and 22 except for lighting fixtures, should use a dedicated grounding wire. If this grounding wire is installed in the same protective conduit as the phase wire, it must have insulation equal to that of the phase wire. Lighting fixtures within explosive zones 2 and 22 can utilize a metal piping system with a reliable electrical connection as a grounding wire, but not the pipeline for conveying substances.
(3) In different directions of the slope in the explosive hazard area, the grounding main should be connected to the grounding body at least twice.

Basic Safety Standards for Explosion-Proof Design in Hazardous Areas (Shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
1. First, conduct the overall explosion protection design
2.定向 release of explosive energy. Around the explosion source, utilize anti-explosion and venting technologies comprehensively. Set anti-explosion walls and windows in the direction of high population density, office areas, and critical equipment. Install venting walls and windows in directions with low human traffic and no critical equipment.
3. Establish safe distances. Minimize the setup of office areas, residential zones, and critical equipment areas within the range less than the safe distance unless necessary; if set up, implement necessary explosion-proof measures.
4. Conversion of non-explosion-proof buildings to explosion-proof. Within the range of less than the safe distance, conduct explosion-proof assessment of the buildings and reinforce those that do not meet the explosion-proof requirements: prevent building collapse; prevent the fracturing of brittle materials such as bricks, concrete, glass, etc., to avoid debris.
5. Locate explosion-proof shelters in hazardous blast areas.
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