Shenzhen ZhongNuo Inspection & Technology Co., Ltd. is based in South China, offering 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 large enterprises such as PetroChina, LG, Huanlan Environment, BOE, and Sinovac Biotech, receiving consistent praise and trust from our clients!
Standard for Explosion-proof Construction Acceptance - Shenzhen Zhongnuo Testing Technology Co., Ltd.
G50058 Specification for Design of Electrical Installations in Explosive Hazardous Environments
GBJ54-83 "Code for Design of Low-Voltage Distribution Equipment and Lines"
G50016 Building Design Fire Prevention Code
AQ3009 Electrical Explosion-Proof Safety Standard for Hazardous Areas
GB/T3836.1 "Explosive Atmospheres, Part 1: Equipment - General Requirements"
GB/T 3836.15 "Design, Selection, and Installation of Electrical Equipment for Explosive Atmospheres"
GB50257 "Code for Construction and Acceptance of Electrical Installations in Explosive and Flammable Gas Atmospheres"
14J938 "Explosion-Resistant and Explosion Ventilation Doors, Windows, Roof, and Wall Building Structures"

Selection of cables and wires for explosive environments shall comply with the following regulations: (Shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
(1) In explosive environments, the rated voltage of insulating conductors and cables used for low-voltage power and lighting circuits should be higher than or equal to the working voltage, with U0/U not less than the working voltage. The rated voltage of the neutral wire should be equal to the phase voltage, and should be laid in the same sheath or protective conduit.
(2) In areas where explosion hazards exist, bare wires should not be used as supply and distribution lines, except within switchboards, junction boxes, or wiring systems using metal conduits.
(3) Copper-core cables should be used in Zone 1. In Zone 2, copper-core cables are recommended, except for intrinsically safe 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 with electrical equipment. Circuits installed in explosive dust environments in Zones 20 and 21, as well as in areas with severe vibration within 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 wiring of cables in explosive environments shall comply with the specifications in Table 5.4.1-1.
(5) The technical requirements for pipeline wiring with steel pipes at voltages below 1000V, excluding circuits of intrinsic safety systems, in explosive environments, should comply with the specifications of Table 5.1.1-2.
(6) In explosive environments, the selection of insulated conductors and cable cross-sections must comply with the provisions of Tables 5.4.1-1 and 5.4.1-2, as well as the following regulations:
1) The conductor's allowable current 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 case specified in clause 2 of this article.
2) The long-term allowable current of the auxiliary line for squirrel-cage induction motors with a voltage rating of 1000V or less should not be less than 1.2 times the motor's rated current.
(7) When installing overhead or bridge-mounted cables, flame-retardant cables are recommended. Plastic sheathed cables without armor can be used when the installation method employs bridge racks that prevent mechanical damage. In areas 2 and 22 where there is no risk of damage from rodents or insects, cables installed in cable trenches can be non-armor cables.

Shenzhen Zhongnuo Testing Technology Co., Ltd. offers a range of explosion-proof engineering services for hazardous areas.
1. Explosion-proof site inspection and consultation
2. Explosion-proof engineering site construction and renovation
3. Explosion-proof construction acceptance
4. Explosion-proof electrical installation, maintenance, and renovation
5. Explosion relief walls, doors, and windows installation
6. Dust Removal Equipment Installation and Retrofitting Construction

Basic Dust Explosion Proof Construction Regulations
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, structural layouts, 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 Inspection Technology Co., Ltd. has summarized the following points:
4. Explosion-proof electrical equipment
Electrical equipment used in dust explosion hazardous areas shall 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. For the 21-zone environment with combustible non-conductive dust and combustible fibers, explosion-proof electrical equipment with dust-proof structure is used. In the 20-zone environment with explosive dust and other 21-zone environments with explosive dust, dust-tight structure explosion-proof electrical equipment is employed, and electrical equipment from different ignition temperature groups is selected according to the different ignition temperatures of the dust.
(2) Galvanized Welded Steel Pipes for Low-Pressure Fluid Transportation
(3) Connections between steel pipes, steel pipes and electrical equipment, and steel pipe accessories should be made with threaded joints. Soldering with sleeves is not permitted, and the following requirements must be met: the threading should be smooth, complete, and free of rust. Power composite grease or conductive anti-rust grease should be applied to the threads. Do not wrap the threads with hemp or insulating tape, nor apply other paints. For steel pipes with a diameter of 25mm or less, there should be at least 5 threads, and for pipes with a diameter of 32mm or more, there should be at least 6 threads.
(4) Flexible explosion-proof conduit should be installed at the following locations for pipeline wiring of steel pipes: at the motor's entry clamp, where direct connection of steel pipes to electrical equipment is difficult, and where pipelines pass through the expansion joints and settlement joints of buildings.
(5) In Zones 20, 21, and 22, it is not advisable to use portable electrical equipment. If portable electrical equipment must be used, YC or YCW rubber cables should be selected for the wiring.
AQ3009-2007 "Electrical Explosion Protection Safety Specification for Hazardous Areas" categorizes dust explosion areas into Zones 20, 21, and 22.
5. Ventilation and dust removal
(1) It is advisable to set up a dust removal system with opposing sections based on the process.
(2) All dust-generating points should be equipped with dust collectors.
(3) There should be no dust sedimentation in the air ducts.
(4) Baghouse dust collectors should be used, with preference given to the external filtration type.
(5) The dust collector 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 baghouse dedusters are best operated with nitrogen, carbon dioxide, or other inert gases as the cleaning gas source.
Fire Protection
(1) Select the appropriate fire extinguisher based on the physical and chemical properties of the dust.
(2) When extinguishing fires, prevent dust from becoming airborne to form dust clouds.
(3) If the combustible material generates explosive gas when in contact with water, do not use water to extinguish the fire.
7. Job Safety
When dust clouds can be ignited by sparks from collisions, measures should be taken to prevent collisions from occurring. Additionally, explosion-proof tools should be used during maintenance.
(2) Do not use rotating grinding wheels and rotating cutting disks for grinding and cutting without equivalent protection measures to flame operations.
(3) All production workshops and storage rooms where dust may accumulate should be cleaned promptly.
(4) Do not use compressed air for well flushing.
(5) In the workplace, production personnel should not wear synthetic fiber garments next to their skin.
Explosion-proof electrical renovations and on-site explosion-proof construction consulting services for hazardous areas - Shenzhen ZhongNuo Testing Technology Co., Ltd.