GB1026413A - Improvements in electrostatic spraying apparatus - Google Patents

Abstract

1, 026, 413. Spray-producers. DE MACHINES ELECTROSTATIQUES. S.A. Feb. 11,1964 [Feb. 22, 1963], No. 7244/63. Heading B2F. An electrostatic spraying apparatus, suitable for spraying a liquid such as paint, is adapted to produce either a low velocity wide angle spray, the dispersion of the spray being aided by a swirling stream of air, or a high velocity narrow angle spray, and includes means for changing from one type of spray to the other whilst the apparatus is in operation. In the embodiment of Fig. 1 paint is fed through a passage 7, along passages between fins 12 while in contact with a material 11 of high resistivity on the internal surface of a hollow electrode 6, and through the gap surrounding the head of a pintle 8 which is spaced from a conical seating recess 10. Compressed air is fed through a passage 13 to an annular chamber 14, through swirl slots 19a and out through an annular opening 26 so that it distributes the paint at a spray angle of between 70 and 140 degrees and at a velocity of about 1Oft/sec When an outer portion 1 of the apparatus is moved with respect to an inner portion 5, Fig. 2 (not shown) valve surfaces 17 and 18 are separated and the compressed air by-passes the slots 19a and issues from the opening 26 as a high velocity non-swirling stream, the spray angle being between 17 and 40 degrees and the spray velocity being 40 ft/sec. Fig. 4 (not shown) depicts an arrangement in which the pintle is controlled by an operating rod and tangential passages leading into an annular cavity produce a swirling stream of air from the opening 26. A high D.C.potential is applied to a member surrounding and spaced from the pintle and paint is fed into the apparatus through a flexible tube. Initial movement of the rod displaces the conical head of the pintle and allows the flow of paint which is distributed by the air stream. Further movement of the rod moves the said member to the right thereby decreasing the opening 26 and producing an air stream of higher velocity. The apparatus of Fig. 5 (not shown) includes a valve operable from the gun butt to control the flow of air through a first passage from which it is fed via tangential passages to the nozzle 26 and emerges as a swirling spray, and through a second passage which produces a high velocity stream of air from the nozzle 26. Fig. 6 (not shown) is provided with an air supply similar to that of Fig. 5 but the liquid supply is provided centrally of the apparatus and the pintle is eliminated.