1、 Specification for Explosion Prevention Safety Inspection of Dust Explosion Sites
2、 General items for on-site explosion-proof safety inspection in dusty areas
1Structure and layout of buildings (structures)
(1) Process equipment with dust explosion hazards or buildings (structures) with combustible dust should be separated from other buildings (structures), and their fire separation distance should comply with the relevant provisions of GB50016
(2) The building should be a single story structure, and the roof should use a lightweight structure
(3) The structural requirements for multi story buildings are as follows:
A、 Multi story buildings should adopt frame structures
B、 Buildings that cannot use frame structures should have explosion vents installed on the walls that meet the requirements
C、 If windows or other openings are used as venting ports, they should be accounted for and ensured to be effective in venting during an explosion
(4) The requirements for evacuation routes are as follows:
A、 The work area should have evacuation routes, and the number and location of evacuation routes should comply with the relevant provisions of GB50016
B、 The door should open outward and no threshold should be set
C、 Detailed road signs and emergency lighting should be set up for evacuation routes.
2Process equipment
(1) If there is a risk of dust explosion in the factory, the process equipment should be located at a higher position in the building and close to the exterior wall.
(2) Process equipment with explosion hazards should be located in open areas outside buildings
(3) The allowable surface temperature of equipment or devices that come into direct contact with dust, such as light sources, heating sources, etc., should be lower than the minimum ignition temperature of the corresponding dust.
(4) The transmission mechanism of equipment and devices in places with combustible dust should comply with the following regulations:
A、 The bearings of process equipment should be dust-proof and sealed. If there is a possibility of overheating, detectors that can continuously monitor the temperature of the bearings should be installed
B、 Belt drive should not be used. If belt drive is used, a differential speed sensor and an automatic anti slip protection device should be installed. When sliding friction occurs, the protection device should be able to ensure automatic shutdown
(5) At the feeding point of the process flow, magnets, pneumatic separators or sieves that can remove impurities from the mixed materials should be installed to prevent collisions between impurities and equipment
(6) Effective measures should be taken to prevent sparks generated by friction between aluminum, magnesium, zirconium and other metal powders or powders containing these metals and stainless steel
(7) To achieve protective parking during an explosion, several power supply control boxes that can interlock with each other should be installed according to the size of the workshop. In emergency situations, the power supply to all motors should be cut off in a timely manner.
(8) The joints, inspection doors, baffles, and explosion vent covers of process equipment should be tightly sealed
(9) The equipment casing should be made of non combustible materials
(10) The operating components of the equipment should operate flexibly without any scraping, bumping, jamming, rubbing, or other phenomena.
(11) When the strength of the process equipment is insufficient to withstand the overpressure generated by internal dust explosion under its actual working conditions, an explosion vent should be installed, and the size of the explosion vent should comply with the relevant provisions of GB/T15605
(12) The location of the explosion vent should be close to the place where the explosion source may occur, and should be opened at the top or upper part of the enclosure as much as possible. It should not be released to flammable and explosive hazardous areas to avoid igniting other combustibles, and should not be released to public places to avoid explosion and injury.
3Lightning protection and anti-static measures
In places with dust explosion hazards, corresponding lightning protection measures should be taken in accordance with the relevant provisions of GB50057. When there is a static electricity hazard, the following regulations should be followed:
(1) All metal equipment, device casings, metal pipelines, brackets, components, parts, etc. are generally directly grounded with anti-static measures. If it is inconvenient or the process does not allow direct grounding, it can be indirectly grounded through conductive materials or products
(2) Instruments directly used for containing charged powders, pipelines (belts) for transporting powders, etc. should be made of metal or anti-static materials
(3) All metal pipeline connections should be bridged.
(4) Operators should take anti-static measures.
(5) The method of eliminating static electricity by directly grounding metal conductors or mesh screens in contact with high-speed flowing powder should not be used,
4Explosion proof electrical equipment
The electrical equipment used in dust explosion hazardous areas shall comply with the relevant provisions of GB12476.1, and the electrical design shall be carried out in accordance with the relevant provisions of GB50058. Explosion proof electrical equipment should be selected based on the level of the explosion hazardous area and the category, level, and group of explosive hazardous substances.
(1) Options for explosion-proof electrical equipment. Except for the dust explosion-proof electrical equipment with dust-proof structure (marked as DP) used in Zone 11 environments with combustible non-conductive dust and combustible fibers, the dust explosion-proof electrical equipment with dust-proof structure (marked as DT) is used in Zone 10 and other explosive dust environments in Zone 11, and different ignition temperature groups of electrical equipment are selected according to the different ignition temperatures of the dust.
(2) The wiring steel pipe should be galvanized welded steel pipe for low-pressure fluid transportation
(3) The connections between steel pipes, electrical equipment, and accessories should be made using threaded connections. Sleeve welding is not allowed and must meet the following requirements: thread processing should be smooth, complete, and free of rust, and electric composite grease or conductive rust proof grease should be applied to the threads. Do not wrap hemp or insulation tape or apply other paint on the threads. Steel pipes with a diameter of 25mm or less should have no less than 5 buckles, and steel pipes with a diameter of 32mm or more should have no less than 6 buckles.
(4) Steel pipe wiring should be equipped with explosion-proof flexible connecting pipes at the following locations: the incoming line buckle of the motor, where it is difficult to directly connect the steel pipe to electrical equipment, where the pipeline passes through the expansion joint and settlement joint of the building.
(5) Mobile electrical equipment should not be used in zones 20, 21, and 22. If mobile electrical equipment must be used, YC or YCW rubber cables should be selected for the wires.
Note: GB50058-1992 "Code for Design of Electrical Installations in Explosive and Fire Hazardous Environments" divides dust explosion sites into Zone 10 and Zone 11
AQ3009-2007 "Safety Code for Electrical Explosion Protection in Hazardous Areas" divides dust explosion sites into zones 20, 21, and 22
5Ventilation and dust removal
(1) It is advisable to set up relatively independent dust removal systems according to the process partitioning
(2) All dust generating points should be equipped with dust hoods
(3) There should be no dust settling in the air duct
(4) Bag type dust collectors should be used, with priority given to external filter types
(5) Dust collectors should be installed outdoors. If installed indoors, their explosion-proof pipes should be directly connected to the outdoors and have a length of less than 3m. The installation of explosion-proof devices should be determined based on the properties of the dust.
(6) Isolation valves should be installed at the inlet and outlet of the dust collector, and temperature monitoring devices should be installed
(7) Pulse jet ash bag filter should use nitrogen, carbon dioxide or other inert gases as the source of dust cleaning gas.
6Fire Protection
(1) Fire extinguishers should be selected correctly based on the physical and chemical properties of dust
(2) When extinguishing a fire, precautions should be taken to prevent dust from rising and forming dust clouds
(3) If the combustibles come into contact with water and can generate explosive gases, water should not be used to extinguish the fire.
7Homework safety
(1) When dust clouds can be ignited by sparks generated by collisions, measures should be taken to prevent collisions from occurring. At the same time, explosion-proof tools should be used during maintenance,
(2) Rotating grinding wheels and cutting discs should not be used for grinding and cutting without equivalent protective measures as open flame operations
(3) All production workshops and storage rooms that may accumulate dust should be cleaned in a timely manner.
(4) Compressed air should not be used for underground blowing.
(5) In the workplace, production personnel should not wear synthetic clothing close to their bodies
Service Hotline: 18924609560 (same WeChat account)
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