Shenzhen Zhongnuo Inspection Technology Co., Ltd. is based in South China, offering explosion-proof technical consulting services including on-site construction, safety inspections, renovations, project acceptance, and explosion-proof installations. We are well-versed in explosion-proof construction standards, boast experienced construction teams, and have served major enterprises such as PetroChina, LG, Hanlan Environment, BOE Technology Group, and Sinovac Biotech, receiving consistent praise and trust from our clients!
Basic knowledge for explosion-proof electrical installation should include the following points:
Division and classification of explosive substances, grouping, and classification of hazardous areas with respect to explosion risk, as well as delineation of regional scopes.
Explosive gases should be classified based on their Maximum Experimental Safe Gap (MESG) or Minimum Ignition Current Ratio (MICR), and grouped by ignition temperature. Combustible dusts can be divided into conductive and non-conductive types based on their electrical conductivity, and grouped by their low ignition temperature. Hazardous areas with explosive risks are categorized into two types: gas explosion hazardous areas and dust explosion hazardous areas. These areas are further divided into three zones (0, 1, and 2) based on the frequency and duration of explosive gas environments. For combustible dust/air mixtures, the zones are categorized into three levels (20, 21, and 22) based on the frequency and duration of their occurrence and the thickness of the dust layer.
2. Selection of explosion-proof electrical equipment for hazardous explosive areas.
The selection principles for explosion-proof electrical equipment are safety and reliability, economic and reasonable. It should be selected based on the grade of the explosive hazardous area and the category, grade, and group of explosive hazardous substances. Refer to the specific selection table in standard AQ3009-2007.
Section 3: Installation of electrical wiring and explosion-proof electrical equipment in hazardous explosive areas.
Installation methods for electrical wiring in explosive gas environments can be categorized into cable wiring and conduit wiring. 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 hazardous temperatures. When avoidance is not possible, preventive measures should be taken. The low-voltage cables or insulated conductors used must have a rated voltage higher than the working voltage of the circuit and not less than 500V. Insulated conductors must be installed within conduits. For more details, refer to training programs on explosion-proof electrical installation, maintenance, and repair.
IV. Inspection and Maintenance of Explosion-Proof Electrical Equipment in Hazardous Areas.
To minimize the ignition hazard of electrical equipment in hazardous areas, initial inspections should be conducted before the equipment is put into operation and during the handover acceptance of the project. Continuous supervision and regular inspections should be carried out to ensure the electrical equipment remains in good condition for long-term use in hazardous areas. The initial and regular inspections should be entrusted to safety production testing and inspection institutions with explosion-proof qualifications.
Inspections and maintenance of explosion-proof electrical equipment should be conducted by qualified personnel meeting specified criteria. These individuals must undergo training covering topics such as explosion-proof types, installation practices, relevant regulations and procedures, as well as the general principles of hazardous area classification. They should also receive appropriate continuing education or regular training and possess relevant experience and trained qualifications. Continuous supervision and periodic inspections should be implemented. Maintenance requirements should propose reasonable corrective measures and equipment replacement procedures.

Shenzhen Zhongnuo Inspection & Technology Co., Ltd. offers explosion-proof construction service in the field of:
Explosive gas environments and hazardous areas with explosive or combustible dust are present in various industries and fields, including petrochemicals, metal smelting, fine chemicals, petrochemical ground facilities (such as gas stations, CNG stations, petrochemical storage and transportation), new energy, special equipment, nuclear power, tunnels, grain processing, wood processing, metal component manufacturing, and environmental protection engineering. Ensuring the anti-explosion safety of these hazardous areas is crucial for safeguarding the economic development of our country and its people.

Basic Explosion-Proof Design Standards for Hazardous Areas (Shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
1. Initial explosion protection overall design
2. Directed release of explosive energy. Around the explosion source, utilize both anti-explosion and venting technologies comprehensively. Set anti-explosion walls and windows in the direction of densely populated areas, office zones, and important equipment. In directions with minimal human traffic and no critical equipment, install venting walls and windows.
3. Establish the safe distance. Avoid setting up office areas, residential zones, and critical equipment areas within the range below the safe distance unless absolutely necessary; if set up, implement necessary explosion-proof measures.
4. Conversion of non-explosion-proof buildings to explosion-proof buildings. Within the range of less than the safe distance, explosion-proof assessment should be conducted on the buildings, and reinforcement should be applied to those buildings that do not meet the explosion-proof requirements: to prevent building collapse; and to prevent the fracturing of brittle materials such as bricks, concrete, glass, etc., resulting in debris.
5. Place explosion-proof shelters in hazardous explosive areas.

Installation of electrical wiring in explosive environments shall comply with the following regulations (shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
Electrical wiring should be installed in environments with lower explosion hazards or away from release sources, and it should comply with the following regulations:
1) When the material is heavier than air, electrical wiring should be installed at a higher level or directly buried. For overhead installation, cable trays should be used; for trench installation, the trench should be filled with sand, and drainage measures should be in place.
2) Electrical wiring should be installed outside the walls of buildings or structures that pose an explosion hazard.
3) In environments with explosive dust, cables should be laid in locations where dust does not accumulate easily 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 lines, it is advisable to avoid areas susceptible to mechanical damage, vibration, corrosion, UV radiation, and heat. If avoidance is not possible, preventive measures should be taken.
(4) Steel pipe wiring may use insulated single-core or multi-core wires without a 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 of the locked zinc-welded type used for low-pressure fluid conveyance. The threaded portion of the steel pipe connection should be coated with lead oil or phosphating paste. In areas where condensation or condensate may form, a sealed joint for draining condensate should be installed on the pipeline.
(5) Electrical wiring for steel pipes in explosive gas environments should be properly isolated 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.
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 conducted between adjacent explosive environments, as well as between explosive environments and adjacent other hazardous or non-hazardous environments. During sealing, the inner surface of the seal should be lined with a fibrous layer as the bottom or separator layer. The effective thickness of the filling layer should not be less than the inner diameter of the steel pipe, and it must not be less than 16mm.
4) Connection components 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 terminating cables or wires, if the internal wires are braided, the terminations should be made using a crimped terminal or lug. The connection and termination of aluminum-core insulated wires or cables should be by crimping, soldering, or spot welding. 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.
explosion-proof electrical retrofitting and on-site explosion-proof construction consulting services for hazardous areas with explosive dangers - Shenzhen Zhongnuo Testing Technology Co., Ltd.