Degreasing baths

Surface cleaning as a preparation for coatings is discussed in Sections 11.1 and 11.2. It is important to control degreasing baths to prevent accumulation of water and formation of corrosive products which will contaminate the atmosphere as well as the objects being degreased. In the case of tri-chlorethylene, stabilisers are added to prevent formation of hydrochloric acid Exclusion of dust is beneficial, and may necessitate filtering the air or use of a temporary protective. 

Degreasing baths remove oil and other pollutants from the surface of metal components before this surface is treated. In due time the contents (1-2 m ) of the degreasing bath become polluted and have to be exchanged for fresh cleaning solutions. This poses several problems ... 

Tj ical lifetimes of degreasing baths amount to 1-2 weeks. By drawing a continuous stream from the degreasing bath, and circulating it over a microfiltration system and concentration tank, oil and dirt can be retained in the concentration tank. 

Microfiltration with HIC s 0.2 xm membranes yields average fluxes of 250 1/m h at temperatures from 40 to 70°C the pH lies between 9 cmd 11. The permeate contains less than 100 ppm oil. This treatment extends the life time of the degreasing bath up to five times pay back time is less than two years. Similar data are reported of Carbosep, Le Carbone Lorraine and Atech membranes [19,22,37,38]. 

In these processes the retention of the detergents has to be monitored in order to keep their concentration in the degreasing bath at the correct level. 

Evaluation of Ultrafiltration to Recover Aqueous Iron Phosphating/ Degreasing Bath... 

Degreasing bath Molybdenum disulfide with grease 85 8 2 Smooth... 

These solvents need to be stabilised [ 12] when degreasing parts in aluminium alloys. Any metallic particles (such as turnings) must be regularly eliminated from the degreasing bath. 

Substrate surfaces are frequently contaminated with oils, greases, etc. and a common pretreatment is degreasing either with steam, or by wiping the surface with solvent-dipped clean cloths, or most effectively in liquid and vapour degreasing baths, possibly using an ultrasonic agitator. Commonly used solvents are 1,1,1-trichloroethane or perchloroethylene, and they should be checked periodically for the formation of corrosive acid. 

Uses Emulsifier, wetting agent for textiles, emulsion polymerization, degreasing baths, electroplating... 

Monamulse 653-83D degreaser, automotive parts UnitollD60 UnitolL60 degreaser, bath gels... 

Since metals are little affected by the temperatures at which solvents boil, and since most solvents do not attack them, industry makes much use of chemical degreasing baths. In these the metal object is suspended above a tank of boiling solvent which causes the vapour to condense on the cooler metal, where it dissolves any grease or oil and runs back into the tank. Fresh vapour free from oil is constantly condensing so that in a very short time the metal is clean. Excess solvent is prevented from escaping by a cooling coil placed around the top of the tank. 

Ceramic microfiltration is another technology that is being applied in solvent and water-based paint production, and paint applying, industries for the treatment of paint-water mixtures, plus other areas such as oil-water emulsions, compressor condensate and degreasing baths. 

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