Explosion proof terminal box is an electrical equipment used for safe connection, distribution, and conduction of electrical energy in hazardous environments. It can be used in explosive hazardous environments such as petroleum refining, chemical, pharmaceutical, etc.
As a key electrical equipment in hazardous environments such as petroleum refining, chemical, pharmaceutical, etc., explosion-proof terminal boxes have a direct impact on circuit safety and explosion-proof performance due to their installation quality. The following are the core precautions that need to be strictly followed during the installation process:
1、 Precautions for Preparation Before Installation
1. Environmental adaptation verification: Confirm the hazardous area level (such as Zone 1, Zone 2 gas hazardous environment, or dust hazardous environment), temperature range, humidity conditions, and corrosive medium type of the installation environment, ensuring that the explosion-proof level, protection level (IP level), and material (stainless steel, cast aluminum, engineering plastic, etc.) of the selected terminal box fully match the environmental requirements to avoid explosion-proof failure due to improper adaptation.
2. Equipment quality inspection: After opening the box, carefully check whether the main body, cover plate, sealing components (sealing rings, gaskets), wiring terminals, fasteners and other components of the terminal box are intact and undamaged, whether there is deformation, cracks, damage or rust; Check whether the explosion-proof surface (explosion-proof product) is flat, without scratches or bumps, and whether the sealing components have good elasticity and no aging; At the same time, verify the product qualification certificate, explosion-proof qualification certificate and other qualification documents to ensure that the equipment is qualified and genuine.
3. Preparation of installation tools and accessories: Choose tools that meet explosion-proof requirements (such as non sparking tools), and avoid using ordinary metal tools that may generate sparks; Prepare suitable fasteners (bolts, nuts, etc., which need to be original factory matching or explosion-proof accessories of the same specifications), sealant (if necessary), cable sealing joints and other auxiliary materials to ensure that the material of the auxiliary materials is compatible with the terminal box and meets the requirements of explosion-proof, waterproof and dustproof.
2、 Precautions for selecting installation location
1. Avoid dangerous locations: It is strictly prohibited to install in positions that directly bear strong impacts and vibrations (such as near equipment vibration sources or directly below pipeline interfaces); Avoid installation in high-temperature baking areas (such as near steam pipelines and heating equipment), and stay away from leakage points and spray ports of flammable and explosive substances to ensure sufficient safety distance from hazardous sources.
2. Ventilation and drainage considerations: Choose a location with good ventilation to avoid the box being in a sealed and humid environment for a long time, and to prevent water accumulation or condensation inside the box; The installation site should have good drainage conditions and should not be lower than low-lying areas on the ground to avoid rainwater and sewage accumulation soaking the box.
3. Reserve space for operation and maintenance: Sufficient maintenance space should be reserved at the installation location, and there should be no obstructions around the box to ensure that the cover plate can be opened smoothly, the wiring operation is convenient, and it is also easy to conduct regular inspections and maintenance in the future.
4. Avoid electromagnetic interference: Keep away from strong electromagnetic radiation sources (such as large transformers and high-frequency equipment) to prevent electromagnetic interference from affecting signal transmission (if the terminal box is used for self-control or communication signal lines), and take shielding measures if necessary.
3、 Precautions for installation process operation
1. Fixed installation specifications: Use bolt fixing method to ensure that the box is installed firmly, smoothly, and without shaking; The fixing bolts should be tightened in place and not loose. For vibration environments, anti loosening washers (such as spring washers and anti loosening nuts) can be installed to prevent long-term vibration from causing fasteners to loosen and damaging the explosion-proof sealing performance.
2. Strict control of explosion-proof sealing: When installing the cover plate, it is necessary to ensure that the sealing components (sealing rings, sealing gaskets) are installed in place without deviation, the cover plate is tightly attached to the box, and the explosion-proof surface is clean and free of debris. If necessary, a small amount of special explosion-proof grease (explosion-proof products) can be applied to the explosion-proof surface to enhance the sealing and rust prevention effect; When installing cable entry ports, suitable sealing joints should be selected according to the cable specifications. After peeling off the cable outer skin, ensure that the sealing joints are tightly attached to the cable. Any excess entry ports should be tightly sealed with original sealing components. It is strictly prohibited to leave unsealed entry ports to prevent flammable and explosive gases or dust from entering the box.
3. Wiring operation specifications: Before wiring, it is necessary to confirm that the circuit has been powered off, and live wiring is strictly prohibited; When wiring, it is necessary to distinguish between power lines and signal lines (intrinsic safety lines and non intrinsic safety lines should be wired separately and should not be mixed in the same terminal block or inlet to avoid cross interference). Wiring should be done according to the corresponding terminal numbers, and the wire connections should be firm, without looseness or virtual connections. The clamping force of the wiring terminals should be moderate to avoid damaging the insulation layer of the wire; The stripping length of the wire should be appropriate, and the metal core of the wire should not be exposed for too long to prevent short circuits or electric sparks.
4. Grounding and equipotential connection: According to equipment requirements and site specifications, ensure that the terminal box is reliably grounded, the specifications of the grounding conductor must meet design requirements, the grounding connection point must be firm and rust free, and the grounding resistance must meet relevant standards (usually not greater than 4 Ω, subject to site specifications); For environments with static electricity risks, it is necessary to establish equipotential connections to avoid the accumulation of static electricity and potential hazards.
4、 Precautions for acceptance and debugging after installation
1. Appearance and sealing acceptance: Check that the box is installed smoothly, the cover plate is tightly closed, and the sealing components are not missing or damaged; All inlet ports and sealing components are installed in place and sealed reliably; All fasteners are tightened without any looseness.
2. Wiring correctness verification: Check the connection status of the wiring terminals one by one, confirm that the wire connections are correct and firm, without misconnections or omissions, and that the intrinsically safe and non intrinsically safe circuits are isolated in place, and the insulation layer of the wire is not damaged.
3. Explosion proof performance and insulation testing: Professional instruments are used to test the insulation resistance of the box to ensure compliance with requirements (usually not less than 1M Ω); For explosion-proof terminal boxes, it can be verified whether the gap between the explosion-proof surfaces meets the standards; If necessary, conduct an air tightness test to check whether the sealing performance of the box meets the standard.
4. Power on trial operation inspection: Power on trial operation can only be carried out after confirming that all installations and tests are qualified; During the trial operation, observe whether the terminal box has abnormal heating, noise, odor, etc., check whether the signal transmission (if applicable) is stable, whether the circuit is running normally, and immediately cut off the power if any problems are found.
5、 Other core precautions
1. Strictly follow the specifications and standards: The entire installation process must comply with relevant national standards such as "Explosive Environment Part 1: General Requirements for Equipment" (GB 3836.1), "Explosive Environment Part 2: Equipment Protected by Explosion proof Enclosures" (GB 3836.2), and follow the equipment installation instructions and on-site construction specifications. It is strictly prohibited to modify the box structure, replace components, or simplify the installation process without authorization.
2. Professional operation: Installation personnel must have corresponding professional qualifications, be familiar with the installation requirements of explosion-proof electrical equipment and knowledge of hazardous environmental safety. It is strictly prohibited for unlicensed or non professional personnel to operate.
3. Clear and standardized labeling: After installation, hazardous environment warning signs, equipment numbers, explosion-proof levels, and other information should be posted in prominent positions on the box for easy identification and maintenance in the future.