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Anti-static grounding Specific requirements

Anti-static grounding Specific requirements

Issue Time:2020-10-14
Specific requirements of anti-static grounding 



The oxygen and acetylene pipes in factories and workshops must be connected as a whole and grounded. All other pipes and equipment that may generate static electricity, such as oil conveying equipment, air compressors, ventilation devices and air pipes, especially air pipes for local exhaust, must be connected as a whole and grounded.

The relevant equipment and pipelines of each system in the workshop should be connected reliably, and the contact resistance at the joints should not exceed 0.03Ω; when the two bolts are normally tightened or metal jumpers are used, there should be at least two grounding points.

Parallel pipes in workshops or on trestle bridges should be connected to each other every 20m if they are 10cm apart; pipes less than 10cm apart or intersecting should be connected at intersections; the pipe and the metal frame should also be connected to each other at a distance of 10cm.

 

Both ends of the gas pipeline trunk and molecular pipelines should be grounded; both ends of the pipeline trestle should be connected to the upper pipeline, and should be connected to the pipeline every 200m~300m; the trestle body should also be specially grounded.

Reliable grounding should be implemented for storage of flammable gas, liquefied gas, liquid hydrocarbons, or other storage tanks with fire hazard; for storage with a volume greater than 50m3, grounding should be laid along its diameter and no less than 2 locations. Avoid accidental damage or disconnection of the anti-static grounding wire and grounding device during use; the flange of the pipeline must have good conductivity.

All auxiliary equipment or tools such as oil injection funnels, floating tank tops, workstations, scales, metal gauges, etc. should be well grounded; when oil cans or drums are filled with oil, they should be connected to the oil injection equipment and grounded.


Automobile oil sump should be equipped with a metal chain, one end of the chain is fixedly connected to the oil sump chassis, and the other end sags in contact with the ground. Before loading and unloading oil, the tank truck should be connected to the storage equipment and grounded; after loading and unloading, the oil pipe should be removed before the jumper and grounding wire can be removed. All equipment for loading and unloading oil must comply with the principles of "grounding first, then connecting the oil pipe" and "disconnecting the oil pipe first, then the ground wire". In solid and powder operations that may generate and accumulate static electricity, calenders, glazing machines and various rollers, mills, screens, mixers and other process equipment should be grounded. [2]


Conductive ground


The use of conductive ground is essentially a grounding measure. The use of conductive ground can not only leak the static electricity on the equipment, but also help to leak the static electricity accumulated on the human body. Conductive ground is ground made of materials with a resistivity of 1×108Ωm or less, such as concrete, conductive rubber, conductive synthetic resin, conductive wood, conductive terrazzo, and conductive ceramic tiles. Spray conductive paint on the insulating board. It can also play the same role as the conductive ground. When using conductive ground or conductive paint to spray the ground, the resistance between the ground and the ground should not exceed 1MΩ, and the contact area between the ground and the grounding conductor should not be less than 10cm2.


Insulator ground


For high-insulating materials that generate and accumulate static electricity, that is, for liquid materials with a resistivity of 1×109Ωm or more, even if they are in contact with a grounded conductor, the static electricity changes little. This shows that general grounding has little effect on eliminating static electricity on high insulators. Moreover, for high-insulation materials that generate and accumulate static electricity, it may increase the risk of sparks. Solid materials with a resistivity of 1×107Ωm or less and liquid materials with a resistivity of 1×108Ωm or less are not easy to accumulate static electricity. Therefore, in order to make the static electricity of the insulator leak faster, the insulator should be grounded through a resistance of 1×106Ωm or a little larger.


Shield


It uses a grounding body (shielding conductor) to be placed close to the charged electrostatic body to increase the capacitance of the electrostatic body to ground, reduce the electrostatic potential, and reduce the risk of electrostatic discharge. It should be noted that shielding cannot eliminate electrostatic charges. In addition, shielding can reduce the possible discharge area, limit the discharge power, and prevent electrostatic induction.