What are the measures to eliminate static hazards?
Measures to remove static hazards include grounding, leakage, neutralization, and process control.
1. Grounding grounding is the easiest way to eliminate static hazards. Grounding is mainly used to eliminate static electricity on the conductor and should not be used to eliminate static electricity on the insulator. If there is static electricity on the insulator, the insulator is directly grounded and the spark discharge is likely to occur. In places where there is a risk of fire and explosion, in order to avoid accidents caused by static sparks,
The following grounding measures should be taken:
(1) Equipment, storage tanks, storage tanks and product conveying equipment, closed transport devices, discharge devices, mixers, filters, drying equipment used to process, store and transport various flammable liquids, gases and powders The device, sublimator, adsorber, etc. must be grounded. If the bag filter is made of a similar article of textile, it can be seamed with a wire and grounded.
(2) Pipes such as oxygen and acetylene in the plant and workshop must be connected into a continuous whole and grounded. All other pipes and equipment that generate static electricity, such as air compressors, ventilation and air ducts, especially those that are partially exhausted, must be connected in a continuous unit and grounded. If the pipe is made of a non-conductive material, the wire should be wound around the pipe or inside the pipe and the wire grounded. Metal joints on non-conductive pipes must also be grounded.
(3) Auxiliary equipment or tools such as oil filling funnel, floating cylinder top, workstation platform should be grounded.
(4) The automobile oil tank should be provided with a metal chain, the upper end of the chain is connected to the tank of the oil tanker, and the other end is in contact with the earth.
(5) In some places with high risk, in order to make the shaft reliably ground, conductive lubricant or grounding method using slip ring and carbon brush can be used. The electrostatic grounding device should be securely connected and have sufficient mechanical strength to be grounded with other grounding devices for other purposes.
2. The leak method uses humidification measures and antistatic additives to cause the electrostatic charge to dissipate itself from the insulator. This method is called leakage.
(1) Humidification. Humidification is to increase the humidity of the air. Humidity has a large impact on electrostatic leakage. As the humidity increases, the surface resistance of the insulator is greatly reduced, the conductivity is enhanced, and the electrostatic leakage is accelerated. If the relative humidity of the air is kept at about 70%, it can prevent a large accumulation of static electricity.
(2) Add antistatic additives. Antistatic additives are special auxiliary agents. Some additives can increase the hygroscopicity or ionicity of the materials after they are added to the static electricity generating materials, thereby enhancing the electrical conductivity and accelerating the electrostatic leakage. Some additives have good electrical conductivity.
(3) Use conductive materials or paper insulation materials. For mechanical parts that are prone to static electricity, they are made of conductive materials as much as possible. The inner layer of the container made of insulating material is lined with a conductive layer or a metal network and grounded; the use of conductive rubber instead of ordinary rubber will accelerate the leakage of electrostatic charge.
3. Neutralization method Neutralization method is an important measure to eliminate static electricity hazards. The electrostatic neutralization method seeks to generate charged ions in places where the electrostatic charge is dense, and neutralizes the electrostatic charge at this point. The electrostatic neutralization method can be used to eliminate static electricity on the insulator. Electrostatic hazards can be eliminated using devices such as inductive neutralizers, high voltage neutralizers, and radiation neutralizers.
4. The humidification mentioned in the process control method is a measure to eliminate the danger of static electricity from the process. However, humidification does not control the generation of static electricity, but accelerates the leakage of electrostatic charges to prevent electrostatic charges from accumulating to dangerous levels. In the process, appropriate measures can also be taken to limit the generation of static electricity and control the accumulation of electrostatic charges. For example: use gear transmission instead of belt drive to reduce friction; reduce the flow rate of liquid, gas or dust substances, limit the generation of static electricity; maintain the normal tension of the belt to prevent slipping; the pipe for pouring liquid to the bottom of the container or close to the side wall, Avoid liquid shocks and splashes, etc. There are other measures that do not fall into the above four measures. For example, in order to prevent the danger caused by static electricity on the human body, workers can wear anti-static overalls and work shoes, and measures such as ventilation and dust removal are also beneficial to prevent static electricity.