Miniature spray guns

Abstract

An external mix miniature spray gun of the airbrush type obtains a spray of paint by directing a jet of gas from a source over a nozzle. A reducing valve for the flow of gas is connected at one end to the source and to an outlet at the other end for discharge into the body of the gun. The reducing valve includes a body of circular end profile with the inlet leading to first generally radial flow passages opening to the side of the valve body and second generally radial flow passages leading from the side of the valve body to the outlet. A sleeve is rotatably retained on the valve body by interengaging threads and spans between the first and second radial passages to define an internal space for gas flow therebetween. A tapered surface in the gas flow space on the interior of the sleeve is arranged to approach or withdraw from a portion of the valve body to enlarge or diminish the gap therebetween as the sleeve is rotated relative to the body. At small degrees of valve opening the second radial passages are masked by the threads of the sleeve so that the threads provide a flow resistance facilitating control at low gas flow rates. With such a valve the flow of air through the airbrush can be shut off in the airbrush itself rather than at the source, the pressure can be adjusted in accordance with the fluid being sprayed, and if the source is an aerosol type bottle the pressure can be regulated to maximize the aerosol life.