Shenzhen ZhongNuo Inspection & Technology Co., Ltd. is based in South China and offers a range of explosion-proof technical consulting services, including on-site explosion-proof construction, safety inspections, renovations, project acceptance, and installation. We are well-versed in explosion-proof construction standards, boasting experienced construction teams and extensive practical experience. We have served major enterprises such as PetroChina, LG, Huanlan Environment, BOE Technology Group, and Sinovac Biotech, receiving consistent praise and trust from our clients!
In recent years, with the continuous development of society and the increasing prominence of safety accidents, people's awareness of safety production has been on the rise, and the governance of potential hazards in dangerous environments is urgently needed.
In various industrial sectors in our country, such as oil, chemicals, ports, coal, and others, there is often a risk of leaks or spills of flammable and explosive gases, liquids, dust, and fibers during production, processing, transportation, and storage. When these substances mix with air, they can form explosive mixtures. If the concentration of the mixture reaches the explosive range, any ignition source can trigger an explosion and severe fires, potentially leading to catastrophic chain reactions. Therefore, equipment used in such hazardous environments must be certified with explosion-proof capabilities. 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.

In accordance with the basic requirements of GB 15577 "Safety Code for Dust Explosion Prevention," for explosion-proof construction and modification in explosive dust environments, the following five main explosion-proof measures can be adopted (shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.).
Explosion-Resistant
1. Definition: A suppression technology that allows the enclosed package to withstand the pressure of a large explosion when combustible dust and gaseous oxidizers or air are present inside, preventing the package from being destroyed.
2. Purpose: By reinforcing the container wall thickness and improving the material, external damage can be minimized even in the event of a dust explosion.
3. Basic Requirements:
When producing and handling powdered materials that can cause explosions, if there is no explosion suppression device and no pressure relief measures, all process equipment should be designed to be explosion-proof and capable of withstanding the overpressure generated by internal explosions without bursting.
(2) The connection parts between various process equipment (such as pipes, flanges, etc.) should have the same strength as the equipment itself. For connections between high-strength and low-strength equipment, explosion-proof devices should be installed.
(3) Equipment with explosion-proof pressure and impact resistance should comply with the requirements of GB/T 24626.
Explosion Relief
1. Definition: A controlled explosion technique that, during an explosion within an enclosed package, allows the high temperature, high-pressure combustion products, and unburned materials to be vented through pre-set weak points on the package to a safe direction before the explosion pressure reaches the package's limiting strength, thus preventing the package from being destroyed.
2. Purpose: To reduce explosion losses by setting up explosion relief devices.
3. Methods: Two types of venting methods are available: Flaming venting and Non-flaming venting.
4. Basic Requirements:
When the strength of the process equipment is insufficient to withstand the overpressure generated by internal dust explosion under actual working conditions, explosion relief ports should be set. The relief ports should be directed towards a safe direction, and the size of the relief ports should comply with the requirements of GB/T 15605.
(2) Dust explosion hazard equipment installed indoors should be vented to a safe outdoor direction through pressure relief ducts. The pressure relief ducts should be as short and straight as possible, with a cross-sectional area not less than that of the relief port, and their strength should be no less than that of the protected equipment container.
(3) For equipment within the room that cannot vent its explosion to the outside via a pressure relief duct, a flameless venting cover should be installed.
(4) Process equipment with inline pipelines should be designed to withstand at least 0.1 MPa of internal overpressure.
3. Explosion Suppression
1. Definition: In the initial stage of an explosion, extinguish the flame and suppress (prevent) the development of dust explosion through physical and chemical action.
2. Purpose: To pre-detect fire extinguishing and explosion suppression through the installation of explosion suppression devices.
3. Basic Requirements:
Process equipment with a risk of dust explosion should be protected with explosion suppression devices.
(2) If a monitoring-type explosion suppression device is used, it should comply with the requirements of GB/T 18154.
(3) Explosion suppression system design and application shall comply with the requirements of GB/T 25445.
Four, Explosion-proof
1. Definition: Technology used to prevent the spread of an explosion after it occurs, through physical and chemical actions.
2. Purpose: To prevent the spread of flame through pipes or other conduits
3. Basic Requirements:
(3) Equipment and facilities with a dust explosion hazard that are interconnected through pipelines should ideally be equipped with explosion-proof devices on the pipelines.
(2) Equipment and facilities with dust explosion hazards that are interconnected through pipelines should be equipped with explosion-proof devices on the pipelines. The shutdown direction should be consistent with the direction of explosion propagation.
Five: Inertization
For processes such as crushing, grinding, drying of powders, and pneumatic conveying through pipelines in sealed containers, inert gases like nitrogen, carbon dioxide, halogenated hydrocarbons, argon, helium, and steam, or inert dusts such as fire extinguishing powder, chemical dry powder, and mineral rock powder are introduced. This is done to dilute combustible components and reduce the oxygen content in the environment.

Basic knowledge to be mastered in explosion-proof electrical construction includes the following points:
Division and grouping of explosive substances, classification and zoning of hazardous explosive 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 are divided into conductive and non-conductive types based on their electrical conductivity, and grouped by their low ignition temperature. Hazardous areas involving explosive substances are categorized into two types: gas explosion hazard areas and dust explosion hazard 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 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 2: Selection of Explosion-Proof Electrical Equipment for Hazardous Areas.
The selection principle for explosion-proof electrical equipment is safety and reliability, as well as economic rationality. The selection should be based on the grade of the explosion hazard area and the category, grade, and group of the explosive hazardous substances. Refer to the specific selection table in standard AQ3009-2007 for details.
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 hazardous temperatures. When avoidance is not possible, preventive measures must 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 detailed information, refer to training courses 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, during the handover and acceptance of the project. For the electrical equipment to remain in good condition and be used safely in hazardous areas for a long period, continuous supervision and regular inspections are required. 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 requirements. These individuals must undergo training covering areas 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. Ongoing supervision and periodic inspections should be carried out. Maintenance requirements should include reasonable remedial measures and equipment replacement procedures.

Explosive circuit protection should 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 a zero-sequence current protection, and the protective devices in Zone 1 and Zone 21 should trip the circuit breaker.
Explosion-proof electrical transformation and on-site explosion-proof construction consulting services for hazardous areas — Shenzhen Zhongnuo Testing Technology Co., Ltd.