GB599315A - A new or improved process and apparatus for coating surfaces with plastic and other semi-liquid compositions - Google Patents

Abstract

<PICT:0599315/III/1> <PICT:0599315/III/2> A process for coating surfaces with semi-liquid compositions comprises the steps of circulating the composition around a closed mixing circuit, circulating a predetermined proportion of the mixture around a further closed circuit constituting a feeding circuit and past a desired position for feeding the composition on to the surface and simultaneously discharging the composition from said feeding circuit at said feeding position directly on to the surface which is to be coated. The apparatus is illustrated diagrammatically in Fig. 7 and comprises a container 11 forming part of a closed mixing circuit 82, a pump 13 to circulate the constituents around the mixing circuit and means indicated at 14 for supplying air under pressure to the circuit to assist in the mixing. A closed feeding circuit 12 is connected to the mixing circuit and valves 28 and 31 direct a predetermined proportion of the composition into the feeding circuit 12 around which the mixed material is continuously circulated by pump 13 while apparatus 15 is included in the closed circuit for supplying the mixture directly from the circuit to the surface to be coated. In using the apparatus shown in Fig. <PICT:0599315/III/3> 1, 2, 4, 5 and 6, the composition (e.g., cement and water) is given a preliminary mix in vessel 60 fitted with paddles 61. This mixture is then poured into container 11, valve 31 closed and valve 28 fully opened when pump 13 circulates the composition, down pipe 22 and up pipe 27, around the closed mixing circuits. Air admitted from receiver 52 through connection 14 passes up the pipe 22 and through the material in container 11 in a direction opposite to the flow of material thus assisting in the mixing. When mixing is complete the air is cut off, <PICT:0599315/III/4> <PICT:0599315/III/5> valve 28 partially closed and valve 31 opened to admit the predetermined amount of material. Control valve is opened and the material circulated continuously around the feeding circuit can now be sprayed on to a surface. Valve 41 controls the supply of composition to the spray gun and a stop 66 prevents it being completely closed. Similarly stop 67 in valve 28 prevents <PICT:0599315/III/6> <PICT:0599315/III/7> <PICT:0599315/III/8> these tubes. Instead of one spray gun a number may be used in series. The spray gun may be replaced by the apparatus of Fig. 10 comprising a valve 72 arranged in branch pipe 73 connected to the junction of pipes 35 and 46 and terminating in an orifice 74. This orifice has a flanged collar 75 holding a flat disc 76 so on opening valve 72 the composition issuing therefrom can be smoothed on to the surface. Figure 11 shows the gun replaced by a brush 80 of a hollow conical form through the opening 81 in which the material flows from the orifice this being completely closed. A tube 16 and valve 68 enable air to be blown back along tubes 35 and 46 in the event of any blockage in 74. Specification 400,508, [Group XXVI], is referred to.