Most of the organic solvents used for degreasing are inflammable and explosive, and the steam of most organic solvents is toxic, especially halogenated hydrocarbon, so necessary ventilation, fire prevention, explosion-proof and other safety measures should be taken when using these organic solvents.
Pay special attention to the following points when using trichloroethylene for oil removal.
① The equipment shall be well sealed to prevent steam leakage. The liquid storage tank of the oil removal equipment shall be provided with sufficient trichloroethylene, and the best dosage shall be to ensure that the heater is submerged and not higher than the height of the workpiece bracket.
② Trichloroethylene will decompose under the action of light, heat (> 120 ℃), oxygen and water under ultraviolet irradiation, and release highly toxic carbonyl chloride (i.e. phosgene) and strongly corrosive hydrogen chloride. When trichloroethylene is used for oil removal, direct sunlight and water should be avoided and aluminum and magnesium workpieces falling into the tank should be fished out in time.
③ Trichloroethylene should avoid contact with alkali substances such as sodium hydroxide, because when alkali substances are heated together with trichloroethylene, dichloroacetylene will be produced and there is a risk of explosion.
④ Trichloroethylene is toxic and has strong anesthetic effect. Smoking is strictly prohibited at the operation site! At the same time, wear protective gloves and masks to prevent inhalation of steam or contact with skin.
⑤ The speed of workpiece entering and leaving the tank should not be fast, so as to avoid "piston effect" to "extrude" trichloroethylene vapor or take it out of the equipment. The in and out speed is generally not more than 3 M / min.
No matter what kind of organic solvent is used for cleaning, all kinds of oily dirt and insoluble impurities on the surface of the workpiece can be removed (special organic solvent is required for some marks and marks), which provides a basic surface for further cleaning and is conducive to further cleaning work. After solvent cleaning, the work piece will be easier to be cleaned by chemical or electrolytic cleaning, which is mainly manifested in: one is easy to clean, shorten the time of chemical cleaning, improve the cleaning efficiency; the other is to extend the service life of chemical cleaning agent.
In actual production, not all workpieces need solvent cleaning. For non oil sealed plates and cutting profiles, the surface oil pollution can be directly removed by chemical oil or alkali corrosion. In recent years, the emergence of some new oil removal processes and cleaning agents with better emulsification performance makes it possible for some unsaponifiable oil products with less pollution and medium surface quality to be cleaned directly without organic solvent cleaning. Without the use of organic solvent cleaning, on the one hand, it can save the cost of organic solvent and simplify the process, which is conducive to improving the production efficiency; on the other hand, it can also reduce the pollution of organic solvent to the environment and the harm to operators.
Pay attention to safety when using solvent. Because most of the organic solvents have low flash point and are easy to ignite, it is strictly prohibited to smoke and fire at the use site, and keep away from the fire source. The operators shall take protective measures.