Static Electricity Protection Measures
(1) Reducing Static Charge Generation
For materials that generate static charge upon contact, materials located close to each other in the charge sequence should be selected, or materials that generate positive and negative charges should be appropriately combined to minimize the final charge generation.
In the design of the production process, the contact area and pressure of relevant materials should be minimized, the number of contacts should be reduced, and the movement and separation speeds should be slowed down as much as possible.
(2) Promptly Dissipating Static Charge
In areas with static electricity hazards, all objects that are electrostatic conductors must be grounded.
Metal objects should be connected to the ground using a metal conductor, while electrostatic conductors and subconductors other than metals should be indirectly grounded.
The total leakage resistance between the electrostatic conductor and the ground should generally not exceed 1 × 10⁶ Ω. The grounding resistance of each dedicated electrostatic grounding body should generally not exceed 100 Ω, and in mountainous areas or other areas with high soil resistivity, the grounding resistance should not exceed 1000 Ω. In certain special cases, to limit the discharge current to ground of electrostatic conductors, it is permissible to artificially increase their leakage resistance to 1×10⁶Ω～1×10⁸Ω, but the maximum should not exceed 1×10⁹Ω.
The relative humidity of the local environment should be increased to above 50%. Humidification can prevent electrostatic hazards, but this method must not be used in Zone 0 of gas explosion hazard areas.
Production process equipment should use electrostatic conductors or electrostatic sub-conductors, avoiding the use of electrostatic non-conductors.
For highly charged materials, electrostatic buffers should be installed at appropriate locations near the discharge port.
For some materials, appropriate amounts of antistatic additives can be added to reduce their resistivity.
Operating tools made of electrostatic conductors used in the production site should be grounded.
(3) Charged bodies should be partially or completely electrostatically shielded, or various forms of metal mesh should be used to reduce the accumulation of static electricity. Simultaneously, the shielding body or metal mesh should be reliably grounded.
(4) When designing and manufacturing process equipment or devices, conditions conducive to electrostatic discharge should be avoided. For example, avoid long, thin, conductive protrusions inside containers and prevent high-speed peeling of materials.
(5) Control the concentration of flammable substances in the gas, keeping it below the lower explosive limit.
(6) Limit the exposed area and width of non-conductive materials.
(7) Avoid using non-conductive materials in layered or nested structures.
(8) The resistance per unit length of hoses and ropes used in electrostatic hazard areas should be between 1 x 10³ Ω/m and 1 x 10⁶ Ω/m.
(9) Metal chains are prohibited in areas with gas explosion hazards.
(10) Use an electrostatic eliminator to quickly neutralize static electricity. An electrostatic eliminator uses external equipment or devices to generate the necessary positive or negative charge to eliminate the charge on charged bodies.
In principle, electrostatic eliminators should be installed near the highest potential of the charged body.
To eliminate static electricity from non-conductive materials, different types of electrostatic eliminators should be used depending on the site conditions. Explosion-proof static eliminators must be used in areas where static electricity is hazardous.