Basic method of anti-static disaster

First, the degree of danger in controlling static electricity places In the place of electrostatic discharge, there must be the presence of combustibles or explosive mixtures to form electrostatic fires and explosions. Therefore, controlling or eliminating combustible materials in the discharge place has become one of the important measures to prevent static disasters.
1. Replacing flammable materials with non-combustible materials In the production process of many industries such as petrochemical industry, organic solvents and flammable liquids (such as kerosene, gasoline and toluene) must be used in large quantities, which brings a very high Big fire hazard. In the cleaning of mechanical equipment, if non-combustible sodium carbonate, trisodium phosphate, caustic potash, water glass aqueous solution, etc. are used instead of kerosene or gasoline, the electrostatic hazard during the washing process of the machine will be greatly reduced.
2. Reduce oxidant content Fill nitrogen, carbon dioxide or other inert gases in places with fire and explosion hazards to reduce the oxygen content of explosive mixtures of gases, vapors or dusts, eliminate combustion conditions and prevent fires and explosions. In general, when the oxygen content of the mixture does not exceed 8%, it does not cause combustion.
For dust explosive mixtures such as magnesium, aluminum, zirconium and hafnium, filling with nitrogen or carbon dioxide is ineffective. It should be filled with inert gases such as argon and helium to prevent fire and explosion.
Foreign tankers of more than 100,000 tons and mixed tankers of more than 50,000 tons are required to be installed with an inert gas system.
Second, process control According to the charging sequence, different materials are used to rub different objects. The polarity of the charge on the object is related to its position in the charged sequence. Generally, the two substances in the charged sequence are rubbed. The former is positively charged, and the latter is positive. Negative. According to this characteristic, in the process, two different materials are selected, and the friction is positively charged with the former, and the negative friction is negative with the latter, and finally the static charges formed on the materials cancel each other, thereby achieving the effect of eliminating static electricity. .
The method of eliminating static electricity by appropriately selecting different materials according to the charged sequence is called positive and negative phase cancellation. For example, the aluminum powder and the stainless steel funnel frictionally negatively charge, and the shellac funnel friction is positively charged, and the funnel which is proportionally matched by the two materials can avoid the danger of static charge accumulation.
2. Choosing a material that is not easy to electrify When the resistivity of an object reaches 10 9 Ω•cm or more, as long as the objects rub or contact each other, they will carry an electrostatic high voltage of several kilovolts or more. Therefore, in the process and production process, materials with a resistivity of 10 9 Ω•cm or less can be selected to reduce frictional electrification. For example, in coal mining, the roller that transports the coal belt is an insulating plastic product, which should be replaced with metal or conductive glue to avoid the generation and accumulation of static charge.
3. Reduce friction speed or flow rate Reduce friction speed or flow rate to limit static generation. In the manufacture of film film, if the film is wound on the rotating shaft quickly, it will generate electrostatic high voltage of several tens of kilovolts, discharge with air, and make the film sensitive and leave marks; if the oil is in the process of filling or conveying, If the flow rate is too fast, it will increase the friction speed between the oil and the pipe wall, resulting in higher static electricity. Therefore, reducing the friction speed and limiting the flow rate is very important to reduce the generation of static electricity.
When the oil pipeline diameter is 1cm, 5cm and 10cm, the maximum flow rates are 8m/s, 3.6m/s and 2.5m/s, respectively.
For non-hydrocarbon liquids, the maximum flow rate should not exceed 1.5 m/s for ether pipes with a pipe diameter not exceeding 12 mm and carbon disulfide pipes with a pipe diameter not exceeding 25 mm. Pipes for transporting esters, ketones, and alcohol liquids, if no spraying occurs, allow a maximum flow rate of no more than 10 m/s.
Third, grounding Grounding is the most common way to eliminate static electricity, mainly used to eliminate static electricity on the conductor. In the production process, the following process equipment should be grounded.
1. Processing, storage and transportation equipment All equipment used to process, store and transport various flammable liquids, flammable gases and powders, such as storage tanks, gas storage tanks, product conveying devices, closed transport devices, drainage devices, mixing The filter, filter, dryer, sublimator, adsorber, reactor, etc. must be grounded. If the bag filter is made of textile or similar items, it is recommended that the wire be seamed and grounded.
2. Auxiliary equipment Auxiliary equipment such as oil filling funnel, floating tank top, workstation table, scale, metal ruler should be grounded. When the oil can or oil drum is filled with oil, it should be connected with the oiling equipment and grounded.
3. Pipes Oxygen, acetylene and other pipes in factories and workshops must be connected as a whole and grounded. All other pipes and equipment that generate static electricity, such as oil conveying equipment, air compressors, ventilation and air ducts, especially air ducts that are partially exhausted, must be connected in one piece. When the parallel pipes are within 10 cm apart, the connecting lines are connected to each other every 20 m.
4. Tank truck When the tank truck is driving, dangerous electrostatic voltage is generated on the chassis of the car due to friction between the car tire and the road surface. In order to remove the electrostatic charge, the tanker should have a metal chain with one end connected to the tank car bottom and the other end in contact with the ground. The tank truck should be connected and grounded with the oil storage equipment before loading.
5. Process equipment In the solid and powder operations that generate and accumulate static electricity, such as calenders, glazing machines, various roller shafts, grinding, sieves, mixers and other process equipment should be grounded.
The connection line for electrostatic grounding shall ensure sufficient mechanical strength and chemical stability, and the connection shall be reliable and shall not be interrupted. The grounding resistance should not exceed 1000Ω at the maximum.
4. Humidification In places with static electricity hazard, when the process conditions permit, air-conditioning equipment, sprayers or wet cloth strips can be installed to increase the relative humidity of the air and eliminate the danger of static electricity. The effect of eliminating static electricity by humidification is remarkable. For example, in some powder screening processes, when the relative humidity is less than 50%, the electrostatic voltage in the container is measured to be 40 kV, and when the relative humidity is increased to 80% or more, the electrostatic voltage is lowered to about 11 kV.
In order to eliminate static electricity, in places where there is a static hazard, it is appropriate to maintain the relative humidity of the site at 70% or more if production conditions permit. If the relative humidity is less than 30%, strong static electricity is generated, so the relative humidity should not be lower than 30%.
Fifth, antistatic agent Antistatic agent is a surfactant. If a small amount of antistatic agent is added to the insulating material, the conductivity and hydrophilicity of the material are increased, the insulating property is destroyed, the surface resistivity is lowered, and the electrostatic charge on the insulating material is promoted. There are many types of antistatic agents, which are summarized as follows:
1. Inorganic salts Such antistatic agents include salts of alkali metals and alkaline earth metals, such as potassium nitrate, potassium chloride, barium chloride, potassium acetate and the like. Such antistatic agents cannot form a film by themselves, and generally require a film-forming substance such as glycerin to be used in combination.
2. Surfactants such antistatic agents include aliphatic sulfonates, quaternary ammonium salts, polyethylene glycols, polyols and the like. Among them, ionic surfactants rely on surface ions to increase conductivity.
3. Inorganic semiconductors Such antistatic agents include inorganic semiconductor salts such as halides of elements such as cuprous, silver, iridium, and aluminum. Such antistatic agents also include conductive carbon black and the like.
4. Electrolyte polymer The antistatic agent can form a low-resistance film by itself, and is a polymer having an unsaturated group such as a styrene quaternary ammonium compound.
In the polyester film industry, the use of alkyl diphenyl ether iodate (DPE) as a surface coating has a good antistatic effect. Experiments have shown that for polyester film (film), the surface resistivity can be reduced from the order of 10 15 Ω to the order of 10 7 Ω at a relative humidity of 65%; if relative humidity is used, if the relative humidity is 65%; Below 60%, the surface resistivity can also be reduced to the order of 10 9 Ω.
Sixth, electrostatic neutralizer Electrostatic neutralizer, also known as electrostatic consumer, it is the use of positive and negative charge phase neutralization method to achieve the purpose of eliminating static electricity.
(Responsible editor Guo Fengqin)

Isotropic Ferrite Magnet

Neodymium Magnets,Barium Isotropic Ferrite Magnet ,Isotropic Ring Ferrite Magnet,Isotropic Ferrite Magnet

Honesun Industrial Co.,Limited , http://www.chinamagnetise.com