Suzhou Explosion-proof Engineering Acceptance Standards - Shenzhen ZhongNuo Inspection

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, with experienced construction teams and a wealth of practical experience. We have served major corporations such as PetroChina, LG, Hanlan Environment, BOE Technology Group, and Sinovac Biotech, receiving consistent praise and trust from our clients!
Equipment protection grounding in explosive environments shall comply with the following regulations (Shared by Shenzhen ZhongNuo Inspection Technology Co., Ltd.)
In accordance with the relevant provisions of the current standard "Code for Design of Grounding for AC Electrical Installations" GB/T50065, the following parts that do not require grounding should still be grounded in explosive environments:
1) Equipment with normal, non-electrified metal enclosures, rated for alternating current (AC) voltages of 1000V or less and direct current (DC) voltages of 1500V or less, on poor conductive ground surfaces.
2) In dry conditions, equipment with alternating voltage ratings of 127V or less and direct voltage ratings of 110V or less typically have non-electrified metal casings.
3) Equipment installed on a grounded metal structure.
(2) In explosive hazardous environments, the exposed conductive parts of the equipment should be reliably grounded. All equipment within explosive zones 0, 20, and 21, as well as other equipment within explosive zones 2 and 22 excluding lighting fixtures, should use specialized grounding cables. If the grounding cable is installed in the same protective conduit as the phase wire, it should have insulation equal to that of the phase wire. Lighting fixtures within explosive zones 2 and 22 may use a metal pipeline system with reliable electrical connections as a grounding cable, but not a pipeline for conveying materials.
(3) In different directions of the slope in the explosion hazardous area, the grounding main should be connected to the grounding body at least twice.

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

Based on the basic requirements of GB 15577 "Safety Code for Dust Explosion Prevention," in防爆construction and modification in explosive dust environments, the following five major explosion prevention measures can primarily be adopted (shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.).
Anti-knock
1. Definition: A suppression technology that allows a sealed container to withstand the explosive pressure when an explosion occurs within it due to the presence of combustible dust and gaseous oxidizers or air, ensuring the container remains intact.
2. Objective: By enhancing container wall thickness and improving materials, external damage is minimized even in the event of a dust explosion.
3. Basic Requirements:
When producing and handling powders that can cause explosions, if there is no explosion suppression device or pressure relief measures, all process equipment should be designed to withstand explosion and be 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 that is resistant to explosion pressure and impact from explosion pressure should comply with the requirements of GB/T 24626.
Explosion Relief
1. Definition: An explosion suppression technology that, during an explosion inside the containment vessel, allows the high temperature, high-pressure combustion products, and unburned materials to be vented through pre-set weak points in the containment vessel to a safe direction before the explosion pressure reaches the containment vessel's limit strength, thereby preventing the vessel from being destroyed.
2. Objective: To reduce explosion losses by installing explosion relief devices.
3. Methods: Two explosion relief methods are available – flameless and flammable.
4. Basic Requirements:
When the strength of the process equipment is insufficient to withstand the overpressure generated by the internal dust explosion under its actual operating conditions, explosion relief ports should be set. The relief ports should face a safe direction, and the size of the relief ports should comply with the requirements of GB/T 15605.
(2) Dust explosion hazard process equipment installed indoors should vent 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 opening, and their strength should not be less than the strength of the protected equipment container.
(3) Equipment within the room that cannot vent its explosion to the outside through a pressure relief conduit should be equipped with flameless venting caps.
(4) Process equipment with inline pipelines should be designed to withstand at least 0.1 MPa of internal overpressure.
3. Suppression of Explosions
1. Definition: In the initial stage of an explosion, extinguish the flames and suppress (prevent) the development of dust explosion through physical and chemical action.
2. Purpose: To pre-detect and extinguish fires, as well as suppress explosions 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 monitored explosion suppression device is used, it should comply with the requirements of GB/T 18154.
(3) Design and application of explosion suppression systems should comply with the requirements of GB/T 25445.
Four, explosion-proof
1. Definition: Technology used to prevent the spread of an explosion after its occurrence, 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 dust explosion hazards that are interconnected by pipelines should ideally be equipped with explosion-proof devices on the pipelines.
(2) Equipment and facilities with dust explosion hazards, interconnected by pipelines, should ideally be equipped with explosion-proof devices. 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 to dilute combustible components and reduce the oxygen content in the environment.

Basic Requirements for Explosion-Proof Electrical Installations in Hazardous Areas (Shared by Shenzhen ZhongNuo Testing Technology Co., Ltd.)
1. Oil-immersed equipment should be used under conditions of no vibration, no tilt, and fixed installation.
2. When using non-explosion-proof equipment for mechanical transmission as partition walls, the following regulations should be observed:
The room for installing electrical equipment should be separated from the explosive hazard area by a solid wall made of non-combustible material.
(2) Transmission shafts should be sealed at the partition wall with stuffing box seals or equivalent sealing measures.
(3) The exit of the electrical equipment room should lead to an environment free of explosive hazards.
(4) When the room where the equipment is installed must be in communication with an explosive atmosphere, a positive pressure relative to the explosive atmosphere should be maintained.
3. Electrical wiring and equipment in explosive environments, excluding inherently safe circuits, should be equipped with overload, short-circuit, and grounding protection. Electrical equipment that cannot experience overload does not require overload protection. Motors in explosive environments, in addition to the necessary protection as required by current standards, should also be equipped with phase failure protection. If the automatic shutdown of electrical equipment could pose a greater risk than the ignition hazard, an alarm device should be used in place of the automatic shutdown device.
4. In emergency situations, appropriate measures should be taken at a suitable location or site outside the hazardous area to disconnect the power to the equipment in the hazardous area. Continuous operating equipment should not be included in the emergency shutdown circuit and should be installed on a separate circuit to prevent the occurrence of additional hazards.
5. The design of substation, distribution station, and control room shall comply with the following regulations:
Transformer stations, distribution stations (including distribution rooms, etc.), and control rooms should be located outside of explosive atmosphere environments. When they are in positive pressure rooms, they can be situated within zones 1 and 2.
(2) For explosive gas environments where the gas is denser than air, the equipment floor of the substation, distribution station, and control room located in the additional 2nd zone of the explosion hazard area should be elevated 0.6 meters above the external ground level.
Explosion-proof electrical modifications and on-site explosion-proof construction consulting services for hazardous areas — Shenzhen Zhongnuo Testing Technology Co., Ltd.