How To Buy And Inspect Explosion-Proof Cranes?

How to Buy And Inspect Explosion-Proof Cranes?

 

 

Explosion-proof principle of explosion-proof crane

 

20 ton explosion-proof cranes, various leakage phenomena will inevitably occur due to the non-standard installation, maintenance and aging of the explosion-proof components of the crane during the production process or under abnormal conditions.

 

 

 

Explosion-proof cranes are to take corresponding measures to control the generation of sparks, arcs, etc., use corresponding explosion-proof technology to control and eliminate electrical sparks and mechanical sparks, use metal gaps to prevent explosions, reduce ignition energy, and prevent ignition sources from contacting explosive mixtures And under certain conditions to improve electrical safety measures, etc., so that it cannot ignite the explosive gas mixture in the environment area.

 

 

 

1. Equipment selection

 

For 20 ton explosion-proof cranes, cranes with corresponding explosion-proof grades should be selected according to the specific working conditions and environment. The explosion-proof components such as safety protection devices, electrical components, and lighting equipment equipped with explosion-proof bridge cranes should not be lower than the explosion-proof grade and temperature group of the whole machine.

 

When there are two or more different explosive substances in the same area, it is necessary to select explosion-proof electrical equipment suitable for the explosion level with high risk and the level with low auto-ignition temperature.

 

Under the same functional conditions, the simpler the structure, the better. Generally, the intrinsically safe type is followed by the flameproof type and the increased safety type. It is also necessary to consider the interchangeability of explosion-proof electrical equipment used in the same project for easy management.

 

 

2. Inspection of main components and safety devices

 

 

② For cranes with explosion-proof grade IIC, the surface of the hook is covered with a layer of copper alloy or engineering plastics.

 

③ Devices and rope guides made of copper alloy, engineering plastics or other non-sparking materials to prevent the wire rope from falling out of the groove are installed.

 

④ Wheel treads and rims are made of copper alloy or other non-sparking materials. The running speed of trolleys should be Less than or equal to 10m/min, and that of carts should be Less than or equal to 25m/min. When the explosion-proof level is lIC level, it should be Less than or equal to 16m/min.

 

 

⑥ Cable rollers, limit touch wheels and limit touch wheels shall be made of bronze brass or engineering plastics with surface resistance not greater than 1GQ. When the explosion-proof level is ⅡC level, the traction rope should be stainless steel wire rope.

 

⑦ The material of the buffer is to be made of rubber or polyurethane with a surface resistance not greater than 1GQ, and the buffers on both sides can contact the end stop or the buffer of another crane at the same time.

 

 

3. Inspection of electrical equipment and control functions

 

① The power supply of the feeding device shall adopt TN-S or TN-C system. Cables should be used for power feeding of large and small cranes, and traction ropes should be provided. The cable of the trolley should be a five-core or four-core cable with one-core grounding core wire, and there is no joint in the middle of each cable.

 

② The lead-in and lead-out cables of flameproof electrical equipment should be tightly sealed with suitable sealing rings, and the unused cable inlets and outlets should be sealed with metal covers with a steel thickness of not less than 2mm; There must be no trachoma, rust layer, mechanical scars on the surface. The explosion-proof surface without electroplating or phosphating layer should be coated with phosphating paste, electric compound grease or No. 204-1 anti-rust oil after cleaning. Painting is strictly prohibited, and the fastening bolts should be complete and tightened without loosening.

 

③ The connection between intrinsically safe electrical equipment and non-intrinsically safe electrical equipment should be associated with explosion-proof safety sheds. The model of the associated electrical equipment must be the same as that on the nameplate of the intrinsically safe electrical equipment.

 

④ For dust explosion-proof electrical equipment, except for combustible non-conductive dust located in Zone 22, the enclosure protection grade of IP5X can be selected, and the rest should be selected for equipment with enclosure protection grade of IP6X.

 

⑤ The insulation resistance measured when 500Vd.c is applied between the circuit and the conductive parts should not be less than 1MQ.

 

 

4. Other

 

 

Before starting the on-site inspection work, it is necessary to identify and evaluate the hazards on the inspection site. The hazards that can be eliminated should be eliminated immediately, and the risks that cannot be eliminated immediately should be assessed and reliable protective measures should be formulated. If there is a risk assessment, the site shall be withdrawn immediately to terminate the inspection activities, and the inspected unit shall be notified in writing.

 

The identification, evaluation, elimination and protective measures taken against the above-mentioned hazard sources and the suspension of inspection shall be recorded in writing, and the written notice of suspension of inspection shall be signed by the liaison personnel of the inspected unit.

 

 

 

Therefore, when inspectors enter the inspection site of explosion-proof bridge cranes, they should wear anti-static work clothes and insulated shoes with no nails or other metal materials on the soles, avoid wearing work clothes that may generate static electricity and sparks caused by friction, and wear safety helmets and protective gloves. .

 

The above are some analyzes and suggestions for the problems existing in the supervision and inspection of explosion-proof cranes in the supervision and inspection of explosion-proof cranes in combination with the daily inspection work. We hope to provide certain references for users and inspection and inspection units, and gradually standardize inspection behaviors to ensure that explosion-proof overhead cranes