GB593899A - Improvements in or relating to cleaning metal parts and baths for use in connection therewith - Google Patents

Abstract

<PICT:0593899/III/1> <PICT:0593899/III/2> The liquid cleansing mixture for cleaning metal parts, according to the parent Specification, comprising an unstable mixture of an emulsion of water and a grease solvent and an unemulsified excess of another or the same grease solvent, is modified in that the emulsion is in an acid condition and preferably has a pH falling within 2.0 to 3.5. The acidity inhibits the tendency of the free solvent emulsifying and forming a stable emulsion by means of the soil, containing emulsifying agents, being removed from the metal parts. The solvents specified comprise kerosene, naphtha, or mineral spirit of intermediate volatility thereto; the preferred emulsifying agent is oleic acid amine soap; other additions may comprise pine oil, and blending agents such as "butyl cellosolve," "cyclohexanol." The above may be compounded to form solutions ready for admixture with the water and acidifiers. The latter may comprise sulphuric, phosphoric, pyrophosphoric, phosphorous, oxalic, maleic, chlor and brom-acetic acids and phthalic acid, and also alkali bisulphates and aluminium sulphate. The preferred method is to spray the parts with the cleansing mixture. Metals which may be etched with the material are preferably dipped in solvent or in the above emulsion preferably unacidified or in the latter underlying the solvent layer and then withdrawn and subjected to the spray cleaning, a film of solvent &c. protecting the metal by this preliminary. In a preferred plant for effecting the spray cleaning comprising a spraying compartment 25 and rinsing compartments 26, 27 through which the metal parts to be cleaned are conveyed, passing through openings in the side walls thereof, the cleansing mixture is supplied to apertured vertical pipes 32 arranged along the rear and front walls of the spraying compartment by means of a pump 38 which withdraws a mixture of the emulsion and solvent from a reservoir below the spraying compartment, the cleansing mixture falling into the reservoir after the spraying operation. The open end of the pump intake pipe 45 lies just below the interface 43 of the stratified solvent and emulsion layers in the reservoir. Similar arrangements of spray pipes, pumps, and rinse water reservoirs are provided with the rinsing compartments 26, 27.