Shenzhen Zhongnuo Inspection & 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, boast experienced construction teams, and have served major enterprises such as PetroChina, LG, Huanlan Environment, BOE, and Sinovac Biotech, receiving consistent praise and trust from our clients!
Basic Safety Design Standards for Explosion-Proof 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, comprehensively utilize anti-explosion and venting techniques. Set anti-explosion walls and windows in directions with high population density, office areas, and critical equipment. In directions with low human traffic and no critical equipment, install venting walls and venting windows.
3. Determine the safe distance. Minimize the establishment of office areas, residential zones, and critical equipment areas within the range less than the safe distance unless necessary; if established, implement necessary explosion-proof measures.
4. Conversion of non-blast-resistant buildings to blast-resistant structures. Within the range of less than the safe distance, blast resistance assessments of buildings should be conducted, and reinforcement for buildings not meeting blast resistance requirements should be implemented: to prevent building collapse; to prevent the cracking and shattering of brittle materials such as bricks, concrete, glass, etc., and the resulting debris.
5. Place explosion-proof shelters in hazardous explosive areas.

Basic Safety Electrical Installation Standards (Shared by Shenzhen Zhongnuo Testing Technology Co., Ltd.)
Explosion-proof electrical construction differs from standard electrical construction due to the increased explosion-proof requirements of its environment. According to industry standards, an explosive environment is defined as one where a mixture of gas, vapor, mist, or dust with air is formed under atmospheric conditions, and when ignited, the flame can spread to the entire unburned mixture. An area where explosive gas environments or flammable dust environments are present in large quantities or are expected to occur, and where special precautions for the structure, installation, and use of electrical equipment are necessary, is called a hazardous area. Explosion-proof electrical construction refers to the work that meets the requirements of explosion-proof electrical conditions, personnel, and operations in explosive environments and hazardous areas, characterized by its strength.

Protection of explosive circuitry shall comply with the following regulations (shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
In the 1st zone, both the phase wires and the neutral line in the single-phase network should be equipped with short-circuit protection, and an appropriate switch should be used to simultaneously disconnect both the phase wires and the neutral line.
(2) For 3kV-10kV cable lines, it is advisable to install zero sequence current protection, with the protective devices in Zones 1 and 21 to operate for tripping.

Basic knowledge for explosion-proof electrical installation includes the following points:
1. Classification, grouping of explosive substances, and categorization, grading, and delineation of explosive hazard areas.
Explosive gases should be classified by their Maximum Experimental Safe Gap (MESG) or Minimum Ignition Current Ratio (MICR), and grouped by their ignition temperature. Combustible dusts, based on their conductivity, can be divided into conductive and non-conductive types, 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 based on the frequency and duration of the presence of explosive gas environments: Zone 0, Zone 1, and Zone 2. The hazardous areas are also categorized into three zones—Zone 20, Zone 21, and Zone 22—based on the frequency and duration of the presence of combustible dust/air mixtures and the thickness of the dust layer.
Section II: Selection of Explosion-Proof Electrical Equipment for Hazardous Areas
The selection principle for explosion-proof electrical equipment is safety and reliability, economic and reasonable. It should be selected based on the grade of the explosive hazardous area and the category, level, and group of the explosive hazardous substances. Refer to the specific selection table in standard AQ3009-2007.
Section 3: Installation of electrical circuits and explosion-proof electrical equipment in hazardous explosive areas.
The 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 explosive 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 specifics, refer to training courses on explosion-proof electrical installation, maintenance, and repair.
Four: 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. To ensure the electrical equipment remains in good condition for long-term use in hazardous areas, continuous supervision and regular inspections should be conducted. 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 general principles, including explosion-proof types, installation practices, relevant regulations and procedures, as well as classification of hazardous areas. 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.
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