Shenzhen ZhongNuo Inspection Technology Co., Ltd. is based in South China, offering explosion-proof construction on-site services, safety inspections, renovations, project acceptance, and explosion-proof installation. We are well-versed in explosion-proof construction standards and have a team with extensive experience. We have served major corporations such as China National Petroleum Corporation, LG, Hanlan Environment, BOE Technology Group, and Sinovac Biotech, receiving consistent praise and trust from our clients!
Shenzhen Zhongnuo Testing Technology Co., Ltd. offers explosion-proof construction service in the field of:
Explosive gas environments and hazardous areas with explosive or flammable dust exist in various industries and fields, including petrochemicals, metal smelting, fine chemicals, petrochemical ground facilities (gas stations, filling stations, petrochemical warehousing and transportation), new energy, special equipment, nuclear power, tunnels, grain processing, wood processing, metal parts manufacturing, environmental protection engineering, and more. Ensuring the explosion-proof safety of these dangerous areas is crucial for safeguarding the economic development of our country and the nation.

In recent years, with the continuous development of society and the increasing prominence of safety accidents, people's awareness of safe production has been rising, and the治理 of potential hazards in dangerous environments is urgently needed.
In numerous industrial sectors in our country, such as oil, chemicals, ports, coal, and others, there is often a risk of leaks or spills of various flammable and explosive gases, liquids, dust, and fibers during production, processing, transportation, and storage. When these substances mix with air, they may form explosive mixtures. If the concentration of the mixture reaches the explosive range, any ignition source can trigger an explosion and severe accidents, including fires and even chain reactions leading to major incidents. Therefore, all equipment used in such hazardous environments must be certified by authorized bodies as explosion-proof products. The use of all equipment in explosion-proof environments must be installed and debugged by experienced engineering companies in strict accordance with explosion-proof construction specifications and acceptance standards before being put into actual production use. This ensures the maximum safety requirements for all stages of the production process.

Basic Dust Explosion Proof Construction Standards
In facilities where explosive dust is present, such as flour mills, feed factories, polishing workshops, and plastic production plants, the requirement for explosion-proof measures on-site is particularly important. 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 installation and retrofitting projects, Shenzhen Zhongnuo Testing Technology Co., Ltd. has summarized the following points:
1. Structure and layout of buildings
(1) Process equipment with dust explosion hazards or buildings (structures) containing combustible dust should be separated from other buildings (structures), and their fire protection distances should comply with the relevant provisions of GB50016.
(2) The building should be a single-story structure, with a lightweight roof design preferred.
(3) The structural requirements for multi-story buildings are as follows:
A. Multi-story buildings are best suited for frame structures.
B. Buildings without frame structures must have explosion relief openings set on the walls in compliance with requirements.
C. If windows or other openings are used as blast relief ports, they must be calculated and ensured to effectively release blast during an explosion.
(4) Evacuation routes must comply with the following requirements:
A. The work area should have evacuation routes, and the number and location of the evacuation routes should comply with the provisions of GB50016.
B. The door should open outward and no threshold should be installed.
C. Detailed road signs and emergency lighting should be installed for evacuation routes.
2. Process Equipment
(1) If there is a risk of dust explosion in the process equipment within the factory building, it should be located on a higher floor and near the exterior wall.
(2) Equipment with explosive hazards should be located in outdoor areas outside of buildings.
(3) Equipment or devices that come into direct contact with dust (such as light sources, heating sources, etc.) should have surface temperatures lower than the respective dust's low ignition temperature.
(4) In areas with combustible dust, the transmission mechanisms of the equipment and installations shall comply with the following requirements:
The bearings of the process equipment should be dust-proof and sealed. If there is a possibility of overheating, a detector capable of continuously monitoring the bearing temperature should be installed.
B. Belt drive is not recommended. If belt drive is used, a speed difference sensor and an automatic anti-slip protection device should be installed. In case of sliding friction, the protection device should ensure automatic shutdown.
(5) At the input stage of the production process, magnets, pneumatic separators, or screens capable of removing impurities mixed with the material should be installed to prevent collision between debris and equipment.
(6) Effective measures should be taken to prevent sparks from being generated through friction between metal powders such as aluminum, zirconium, or powders containing these metals with stainless steel.
(7) In the event of an explosion, protective stopping should be achieved by installing several power supply control cabinets that can interlock with each other, according to the size of the workshop. In emergencies, the power supply to all motors should be promptly cut off.
(8) All process equipment joints, inspection doors, baffles, and explosion relief cover plates should be sealed tightly
(9) The equipment housing should be made of non-flammable material
(10) The moving parts of the equipment should operate smoothly without any scraping, bumping, jamming, or rubbing.
(11) When the strength of the process equipment is insufficient to withstand the overpressure generated by internal dust explosion under actual working conditions, explosion relief openings should be provided, and the size of the relief openings should comply with the relevant provisions of GB/T15605.
(12) The venting port should be located near potential ignition sources and should ideally be placed at the top or upper part of the containment structure. It must not vent towards flammable and explosive hazard areas to prevent igniting others, and it must not vent towards public areas to avoid causing injury from the explosion.
3. Lightning and Static Electricity Protection
Hazardous dust explosion areas should adopt corresponding lightning protection measures in accordance with the relevant provisions of GB50057. When static electricity hazards are present, the following regulations should be adhered to:
(1) All metal equipment, enclosures, metal pipelines, brackets, components, and parts, generally adopt anti-static direct grounding. For those that are not convenient or not allowed by the process to be grounded directly, grounding can be achieved indirectly through conductive materials or products.
(2) Equipment directly used for containing electrostatic powder, such as conveyance pipes (belts) for the powder, should be made of metal or anti-static materials.
All metal pipe joints should be bridged.
(4) Operators should take anti-static precautions.
(5) Do not use the method of contacting a directly grounded metal conductor or screen with high-speed flowing powder to dissipate static electricity.

Selection of cables and wires for explosive environments shall comply with the following regulations: (Shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
In explosive environments, the rated voltage of insulated conductors and cables used for low-voltage power and lighting circuits should be higher than or equal to the working voltage, and U0/U should not be less than the working voltage. The rated voltage of the neutral line should be equal to the phase voltage and should be laid in the same sheath or protective tube.
(2) In explosive danger zones, except for wiring within distribution panels, junction boxes, or metal conduit wiring systems, unshielded wires should not be used as supply and distribution lines.
(3) Copper-core cables should be used in Zone 1. In Zone 2, copper-core cables are recommended except for intrinsic safety circuits. When aluminum-core cables are used, their cross-sectional area must not be less than 16 square millimeters, and copper-aluminum transition joints should be used for connections to electrical equipment. Circuits installed in explosive dust environments in Zones 20 and 21, as well as in areas with severe vibration in Zone 22, should use copper-core insulated conductors or cables.
(4) In addition to the circuit of this pressure safety system, the technical requirements for cable wiring in explosive environments shall comply with the specifications in Table 5.4.1-1.
(5) The technical requirements for pipeline wiring in explosive environments with voltages below 1000V, excluding circuits of intrinsic safety systems, shall comply with the specifications of Table 5.1.1-2.
(6) In explosive environments, the selection of insulated conductors and cable cross-sections shall meet the requirements of Tables 5.4.1-1 and 5.4.1-2, in addition to the following:
1) The conductor's allowable current carrying capacity should not be less than 1.2 times the rated current of the fuse element and 1.2 times the setting current of the long-time delay overcurrent release of the circuit breaker, except for the situations specified in item 2 of this clause.
2) The long-term allowable current for the branch circuit of squirrel-cage induction motors with a voltage of 1000V or less should not be less than 1.2 times the rated current of the motor.
(7) When installing overhead or bridge-mounted cables, it is advisable to use flame-retardant cables. Plastic-sheathed cables can be used without armor when the installation method employs bridge structures that prevent mechanical damage. Non-armor cables can also be used for cable installations in cable trenches in Zones 2 and 22 where there is no risk of damage from rodents or insects.
Explosion-proof electrical modifications and on-site explosion-proof construction consulting services for hazardous areas — Shenzhen Zhongnuo Testing Technology Co., Ltd.