Patent GB-673247-A (GB)
Title: Process and apparatus for preventing the dispersion of dust by sand blasting apparatus
IPC: B24C5/02
Filed: 1950-04-11
Abstract: 673,247. Sand-blast. E.C.T.A. ENTREPRISE DE CONSTRUCTIONS ET TRHAVAUX D'ART. April 11, 1950 [April 11, 1949], No. 8923/50. Class 60. A process for .intercepting harmful dusts arising from a sand blast apparatus, by the interposition between the dust and the ambient air of a protective screen containing water, is characterised, by the fact that this screen is formed by air under pressure containing in suspension particles of water atomized by the air under pressure. A device for carrying out the process comprises a base component 1, an end component 2 formed with a frusto-conical skirt or mouth portion and secured to the base component, a first annular disc 7 secured to the end component 2 and a second annular disc 11 secured to the disc 7. The base component 1 has an axial bore 14 to receive the sand blasting tool to. which it is secured by a screw 15. The upper face of component 1 has concentric annular grooves 18, 19 separated by annular rib 20. The outer groove 18 communicates through passage 21 with a fitting 22 adapted to be connected to a source of air under pressure; the inner groove 19 communicates through passage 23 with a fitting 24 adapted to be connected to a source of water under pressure. The component 1 is externally threaded at 3. The end component 2, Fig. 4, comprises a sleeve 26 internally threaded at 3 to screw on to the externally threaded portion 3 of the base component 1; a portion 27 with an internal frusto-conical surface 28 and reinforced at its edge 29, and a flange portion 25 provided with two circular series of holes 30, 31 registering respectively with the air groove 18 and with the water groove 19 in the base component 1. An annular groove 32 in the flange 25 receives the annular rib .20 on base component 1, a gasket 5 being compressed in the groove by the rib; inner and outer gaskets 4, 6 are also interposed between the components 1, 2. The first annular disc 7; Fig. 6, is externally threaded at 8 to screw into the internally threaded portion 8 of the. flange 25 of the end component 2. The disc 7 has a peripheral recess 33 on its under side which registers with the air holes 30 in the end component 2; the edge 34 of the disc is frusto-conical. The disc has a circular series of holes 35 registering with the water holes 31 in the end component 2. Gaskets 9, 10 are interposed between the disc 7 and component 2. The second annular disc 11, Fig. 7, is externallv threaded at 12 to screw into the internally threaded portion 12 of the. first disc 7. The disc 11 has a peripheral recess 37 on its under side which registers with the water holes 35 in the first disc 7; the edge 38 of the disc is frusto-conical. A gasket 13 is interposed between the discs 7, 11. In use, air under pressure admitted through the fitting 22 passes through passage 21, groove 18, and holes 30 to recess 33 of disc 7, finally escaping through the thin conical passage between the surfaces 28 and 34, 38. Water admitted through the fitting 24 passes through passage 23, groove 19 and holes 31, 35 to recess 37 of disc 11 from which it is drawn by the thin layer of air escaping between the walls 28, 38. In this way there is obtained a thin conical screen produced by a mixture of water and air which positively stops sand dust. The thickness of this screen and the relative proportions of water and air are regulated by replacing gaskets 9, 10, 13 by others of different thickness.