Abstract: A trigger operated air valve suitable for controlling both the flow of air to and the flow of feedback air from a nozzle assembly in high volume low pressure (HVLP) spray guns. A trigger moves a spindle against the pressure of a spring. As the trigger is moved, a first valve is opened to initiate a main flow of air to the spray gun nozzle assembly prior to opening a second valve which initiates the flow of feedback air from the nozzle assembly. When the trigger is released, the second valve is closed to terminate the flow of feedback air prior to closing the first valve to terminate the main flow of air to the spray gun nozzle assembly.

Abstract: A feedback air pressure sensing system is described, for use with spray guns, comprising an air pressure feedback line (1), an air regulator (2) with an air cap (3). Air is supplied from air line (4) via regulator (2) to a dual air-feedback valve (5) operated by trigger (6). Air continues along line (7) to spreader control valve (8) supplying fan air to spray gun cap (3). Air is also fed via line (9) to supply atomising air to air cap (3). The regulator (2) comprises a body (13), an inlet (16) for a main air supply to first (14) and second (15) air chambers, an inlet for feedback air to a third air chamber (26), a diaphragm (19) between outlet chamber (25) and a pilot chamber (27), the diaphragm (19) being supported in the regulator body (13) by a spring-loaded valve (18), and spring loaded adjustment means (24).

Abstract: A pressure test gauge is described, more particularly for testing the air pressure at the outlet of a spray gun. The pressure test gauge comprises a body having an inlet which may take the form of a replaceable screw-in-unit sealed airtight with the body. The unit encircles the inlet and connects with passages passing through body. The passage is a small bore tube which connects the inlet with a pressure gauge which has a display. Intermediate the inlet unit and gauge is a valve comprising a barrel with an outer screw-thread screwed into the body. Extending axially of the valve is a metering hole. The gauge body may have ribs for facilitate gripping the body and a bracket with screws to secure it to a wall.

Abstract: An indexing air cap is described comprising an air cap (8), mounted to be adjustably rotatable on the spraygun body (1), a baffle (10) having a recess (12) and a seal (11) of low density plastics material, such as polyethylene, being located between the baffle and the spraygun body. The baffle (10) and the seal (11) having a plurality of holes (16) passing axially through them and being circumferentially spaced from each other. A pin (17) passing through an aligned set of the holes (16) in the baffle and seal to connect with a blind hole (18) in and lock them to the spraygun body (1). Rotation of the air cap through a predetermined angle of 90.degree. indexes the air spray cap to control the radial position and targeting of the spray pattern of the fluid being sprayed. The spray gun body has a mounting aperture which receives a mounting stud. Bevelled washers on the mounting stud are compressed to expand into engagement with the mounting aperture for locking the gun body to the mounting stud.

Abstract: A needle packing assembly is described comprising an annular seal (1) of ultra-high molecular weight plastics material such as polyethylene. A stepped concentric passage (4) passes through the seal with a shoulder (6). The outer end of the inner wall of the passage has a sealing lip (7) formed by a 15.degree. angle with the inner wall. The lip engages a needle (8) of a valve preventing the ingress of fluid past the seal. The assembly also includes a liner (9) made of a lower molecular weight yieldable plastics material such as P.T.F.E. to provide a slidable seal with the needle (8). The liner is forced against the shoulder (6) via a packing piece (10) and disc springs (12) by a nut (14) screw-threaded onto a sleeve in a spraygun. Adjustment of the nut (14) forces the liner to expand forming a self-lubricating bearing with the needle (8) and forces the sealing lip into engagement with the needle to prevent the passage of fluid past the seal.

Abstract: A miniature electronic pressure gauge is described comprising a case (10) having an aperture leading to a transducer (1) connected to an amplifier (3), the transducer (1) and amplifier (3) being powered from a power source (2) in the form of a storage battery such as a Nicod battery. A pressure signal from the amplifier (3) is fed to a linearization circuit (4) and to an analogue/digital converter (6) clocked with pulses from clock generator (5). The output of converter (6) is fed to a decoder/driver (7) for a seven segment L.C.D. (8). In a preferred construction the pressure gauge is releasably retained in a fluid-tight engagement in a bore in the wall of a pressure chamber of a paint spray gun.

Abstract: A spray gun operable by low pressure high volume air is described. The spray gun (10) comprises an air cap (128) formed with a central spraying aperture and a fluid nozzle (70) projecting toward the spraying aperture, the profile of the nozzle is a plain frustum of a core terminating at a small front face bounding an orifice through which fluid is discharged. The arrangement being such that in operation a flow of atomizing air that emerges through a gap between the nozzle (70) and the air cap (128) attaches to the nozzle (70) and to an emergent fluid jet which assumes a conical form that is a continuation of the nozzle surface and changes to a parallel jet before it breaks up into atomized droplets.

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.