Prevention of electrostatic in paint production 2

In the paint production process, the biggest hazards caused by static electricity are explosions and fires. Although the amount of static electricity is not large, because of its high voltage, it is prone to discharge and electrostatic sparks. Therefore, in workplaces with flammable liquids, static sparks may cause fires;

In places with explosive gas mixtures or explosive fiber mixtures, an explosion may be caused by static sparks.

There are the following situations in places prone to static electricity fire accidents during the paint production process.

1.When using pipes to transport solvents and resins with resistivity in 10¹¹-10¹⁵ ohm·cm, especially when using plastic pipes such as polyethylene, static electricity is more likely to occur. Experiments show that when using polyethylene plastic pipe to transport toluene, the static voltage can be measured as high as 25,000 volts.

For example, a paint factory used a plastic tube to pump toluene from a 53-gallon iron bucket to a storage tank. The first bucket was pumped smoothly. Then, about two-thirds of the second bucket was pumped, an explosion occurred and caused a fire. An operator died. The reason is that when the plastic pipe transports toluene, it rubs with toluene to generate static electricity, and the discharge spark ignites the toluene vapor and causes a fire.

2.When pouring a solvent with a resistivity of 10⁷-10¹¹ ohm·cm, if the solvent has a strong impact with the container, or the scouring splash will generate static electricity.

For example, a paint factory uses an oil tank truck to load and unload the fuel oil for the boiler. The tank truck stops at the entrance of the oil storage tank, inserts the oil drain hose into the oil inlet of the oil storage tank, opens the cut-off door and the upper cover of the tank truck tank, and starts unloading. After working for about a minute, there was a sudden explosion with a loud noise, which caused a fire. The reason is that the position of the oil pipeline is too high, as much as 3 meters from the oil surface, and the oil directly impacts the liquid surface in the tank to generate static electricity. The tank car body, the tank and the oil discharge hose and other oil unloading facilities have no conductive grounding device, and the static charge cannot release, generated electrostatic discharge sparks causing oil vapor deflagration.

3.Static electricity may be generated during the resin dilution process and the mixing process of paint mixing. Also in the filtration process of solvents, resins and varnishes, static electricity will also be generated due to the friction between the material, the container and the filter.

A paint factory used a 20-mesh wire mesh nailed on a wooden frame as a filter, and the iron red paint slurry was pumped by a gear pump through the filter into a storage tank, and a fire accident occurred. The reason is that the wooden frame barbed wire filter rests on the storage tank and is in an insulated state. The static electricity generated by the friction between the iron red paint paste (phenol alcohol paint paste) and the filter screen cannot leak and gradually accumulates. Finally, the discharge spark causes combustion.

4.When the resin is smelted, sampling with a metal sampler can also generate static electricity.

For example, when a paint factory is refining phenolic resin, a small iron spoon is used as a sampler to take samples. Burning occurred when the iron spoon left the resin surface after sampling. The reason is that when the sampler quickly leaves the resin, it rubs against the resin to generate electrostatic discharge sparks, which ignite the solvent vapor in the pot and burn.

5.When organic powders such as phthalic anhydride, pentaerythritol and rosin are fed, static electricity will be generated when the powder rubs and collides with the container wall or other appliances.