GB764171A - Improvements in or relating to surface treating apparatus - Google Patents

Abstract

<PICT:0764171/III/1> <PICT:0764171/III/2> In a surface coating apparatus, a jet of coating material is directed at a surface to be coated by a blast gun to which the material is fed by suction in a material supply conduit leading to the gun, and additional suction means are provided to reverse the flow of coating material in the conduit when the suction feeding the material to the gun is cut off. The mobile apparatus comprises a source of compressed air 14. The air passes through a valve V and aridifier 18 to pipes 21, 22. The pipe 22 leads to a valve G, controlling the supply to a gap 62 between a material supply jet 60 and an outer tube 61 whereby the coating material is drawn through the jet towards the surface to be coated. Coating material is supplied to the jet 60 from a pipe B having a T connection 90 with an orifice 85 connected to a suction pipe F and a coating material supply chamber 30. A pipe E conveys coating material from the surface treated to a reclaimer R. Compressed air passes along the pipe 21 to an ejector P. Suction at the orifice 23 draws any dust from a cyclone S connected to the reclaimer. The reclaimer has a passage between members 33 and 41 and a screen 42. The coating material passes into a chamber 31 from the pipe E, the chamber having baffles 34, the material falls on to the member 33. The compressed air passes to a chamber 35 and then to chamber 38 the outlet from which flows air across the flow of material whereby heavy particles fall on to a screen 42 and descend to a chamber 30 (coarser particles being retained by the screen) fine particles are blown into a space between members 41, 33 and up passage 48 to the cyclone S. Particles collect at the base 29 of the cyclone and can be removed, the residue being either evacuated to the air or a dust bag is attached to the ejector P to remove the remaining particles. To adjust the air velocity in the passage between members 33 and 41 for particles of various densities the member 41 is adjustably mounted. The orifice is also changeable to obtain the correct flow of material in the tube B. The gap 62 is also adjustable by screwing the jet to obtain the required force of material. In operation, the valve V is first opened and the air cycles through the tube F and reclaimer. When the valve G is opened, suction at the jet 60 causes material to be impelled down the pipe B through the shell 72 to impinge with great force on the surface. Surplus coating material passes up the pipe E to the reclaimer R drawing in air through an air permeable skirt 63 contacting the surface. On closing the valve G the suction in the line F draws coating material from the tube B into the reclaimer and when the pipe B is cleared, the material continues to cycle until either the ejector pump P is shut down or the valve G is opened and coating is resumed. The apparatus can be used without the reclaimer and cyclone.