Abstract: A spray gun (1) includes a head (2) having an element (5) for connecting a liquid hose (7) as well as a handle member (3) having a member (6) for connecting a compressed air hose (8). The liquid hose (7) is, along the major part of the length thereof, drawn inside the wider compressed air hose (8), a coupling part (10) of the multi-way type being connected to the connection member (6) of the handle member (3). The coupling part includes a main duct (11) for compressed air, as well as at least one branch duct (14), extending at an angle to the main duct, through which the liquid hose (7) is drawn and which includes at least one sealing (18) which air-proofly cuts off an annular gap between the inside of the branch duct and the outside of the liquid hose.

Abstract: A paint system includes a plurality of supply tanks that can be selected for supplying powder paint to a spray site, each having a supply line connected to the supply tank and having an end section, a spray gun, and a purge air supply. Each end section is configured for selective connection to the spray gun to spray powder paint from the supply tank and also for connection to the purge air supply to blow residue powder paint in the supply line back into the supply tank. A control device operably connects a fluidizing air supply to each supply tank. The control device is configured to fluidize the powder paint in each tank at a low standby pressure when the supply tank is not in use, and to fluidize the powder paint in the tank at a higher operating pressure when the supply tank is selected for use. Methods related to the above cause the color change to be very efficient and quick, with low waste of powder paint.

Abstract: A paint injector for digital printing in which paint is deposited in metered amounts on a print medium comprises a wheel rotatable by a shaft of a motor, an idler disposed in a paint reservoir, and an endless cable disposed around the wheel and the idler. The motor is preferably computer controlled such that the rotation of the wheel and thus movement of the cable is selectively controlled. As the wheel is rotated, paint contained within the paint reservoir coats the cable and is thus drawn by the cable in front of an air stream. The air stream pulls the paint from the cable and carries it toward the print medium. By employing a plurality of such paint injectors into a single print head, each containing a different color of paint, and secured to a computer controlled, movable carriage positioned over the print medium, a digital image can be painted by the print head on the print medium.

Abstract: Apparatus for dispensing a fine spray of liquid particles comprises a hollow tubular casing (1) whose internal cross section is formed with at least one abutment surface. A tubular liquid source (2) is positioned within the casing (1) with the abutment surface in close contact with the outer surface of the source to provide support thereto. The casing (1) includes a passageway for the flow of air from a mouthpiece (3) positioned at one end of the casing (1) to a nozzle (9) positioned at the other end of the casing (1) into which the discharge end of the liquid source protrudes. The liquid source may comprise a pen formed with a nib (14) of absorbent material.

Abstract: An in-line point of use filter includes a restrictor flow valve and pressure gauge port integral therewith. The filter includes an internal threaded spindle which rigidly retains a coalescing filter in place. As a result of the compact spindle and filter arrangement, the entire filter assembly fits under a suction feed paint sprayer and allows the combined sprayer and filter unit to stand without toppling. The threaded spindle threads coaxially with a valve body and conducts compressed air therethrough. The compressed air passes from the threaded spindle directly into the filter media and transversely therethrough, and then from the filter media on to the external filter housing and longitudinally therewith into a small chamber carrying the pressure gauge port, the small chamber which is coupled directly into the sprayer body air inlet.

Abstract: A paint supply system for a painting robot, the system includes a paint spraying device mounted on a tool holder at the outer end of a robot arm and having an adapter unit for mounting on the robot arm close to or in direct contact with the paint spraying device, first and second supply lines for supplying first and second painting fluids to the adapter, and a third supply line for supplying a cleansing fluid to the adapter. The adapter includes a first inlet duct connected to the first supply line, a second inlet duct connected to the second supply line, a third inlet duct connected to the third supply line, an outlet duct connected to the paint spraying device, first valve means for connecting the first inlet duct to the outlet duct, second valve means for connecting the second inlet duct to the outlet duct, and third valve means for connecting the third inlet duct to the outlet duct.

Abstract: A paint cup mounting arrangement including a mounting cylinder fastened to a paint spray gun by a screw joint and having a coupling flange around the periphery, a socket sleeved onto the mounting cylinder and having an inward coupling flange forced into engagement with the coupling flange of the mounting cylinder, a paint cup fastened to the socket by a screw joint, a paint guide tube mounted within the mounting cylinder and the socket and sealed by rubber seal rings and adapted to guide paint from the paint cup to the paint spray gun, and a compression spring mounted within the mounting cylinder around the paint guide tube to impart a backward pressure to the socket and to force, the paint cup being adjusted to a vertical position by forcing the socket inwards to compress the compression spring and to disengage the coupling flange of the socket from the coupling flange of the mounting cylinder and then turning the socket about the mounting cylinder.

Abstract: A spray gun is provided with a handle part (6) and a housing (2) having a connecting part (3) for a pressure can, said connecting part being provided with a check valve. The housing (2) receives a nozzle pipe (10) bearing a nozzle (11) at the free end, into which pipe a spring-loaded nozzle needle (12) acting upon the opening of the nozzle (11) extends. The nozzle needle is operable via a pivoted lever (9) mounted in the housing (2). To permit the position of the pressure can to be varied and fixed relative to the handle part (6) while involving a simple structure, the housing part (17) bearing the connecting part (3) for the pressure can is adapted to be rotated around the axis (19) of the nozzle needle (12) relative to the housing part (18) bearing the handle part (6).

Abstract: A paint spray apparatus includes a plurality of paint sprayers installed in a paint spray booth. Each paint sprayer includes a paint spray head pivotably mounted on the end of a movable paint spray arm. The paint spray arm and paint spray head are movable on multiple axes by servo motors, which are controlled by servo drives mounted on or beside the paint sprayer. The spray of the paint spray head is controlled by a plurality of proportional solenoid valves mounted on the paint sprayer. The movement and spray of the paint sprayers are controlled by a computer having an interface to an optical fiber. The optical fiber connects the computer to the servo drives in series in a token ring network.

Abstract: A spray gun for applying a liquid spray coating, such as paint, to a surface incorporates a light source and detection system for analyzing the position of the spray gun relative to a worksurface in order to optimize application of the coating to the surface. The light source is preferably in the form of a laser which emits a beam of light toward the worksurface. The laser is interconnected with the housing of the spray gun in a location over the spray gun handle so as not to effect the center of gravity of the spray gun. Optical sensors are mounted to the spray gun housing for receiving light reflected from the work-surface, and the sensors are interconnected with a processor for providing the operator with a real time visual indication as to compliance with predetermined paint application criteria. In addition, information can be stored to memory and downloaded for subsequent analysis.

Abstract: An apparatus for electrostatically coating a workpiece has an insulating separator valve mechanism for electrically separating a paint supply passage for supplying an electrically conductive paint to a coating gun, into a paint supply passage to which a high voltage will be applied and a paint supply passage to which no high voltage will be applied. The insulating separator valve mechanism has a first valve body connectable to said paint supply passage through a first on/off valve, and a second valve body connectable to said paint supply passage through a second on/off valve. While the first and second valve bodies are connected to each other and the first and second on/off valves are closed, a paint trap is cleaned by a cleaning medium, which is discharged into a second dump passage. A process of cleaning the paint trap for a paint color change is efficiently and reliably carried out to reliably remove paint residuals from the paint trap.

Abstract: A filter for a liquid spraying device such as an airless paint sprayer. The filter separates unwanted foreign material and clumps from a liquid before the liquid is pumped into a liquid spraying device. The filter is removably mounted on a hose of a liquid spraying device to filter the liquid as it is extracted into the hose. The filter has a frusto-conical surface member having a hollow cavity, a top surface, and an open base terminating at an annular wall around the perimeter of the base. A plurality of holes surround the surface of the frusto-conical surface member wherein the holes are formed at an angle of about 90.degree. to a plane spanning the base. Removably attached to the annular wall is a circular disk having a planar surface terminating at a ring such that the ring projects about perpendicularly from the planar surface. The circular disk has a coupling projecting about perpendicularly around a center point of the planar surface.

Abstract: To provide an air brush with a function of spraying an ink coating of a writing material, a holder b holding attachably and detachably a writing material a is mounted to an air brush main body 1 having a coating storing vessel 5, a brush tip a1 of the writing material a held by the holder b is adjacently disposed directly in front of a nozzle 2 of the air brush main body 1 at a predetermined angle of inclination whereby the ink coating impregnated in the brush tip a1 is atomized by impinging a jet stream from the nozzle 2 onto the brush tip al.

Abstract: A disposable liner for a pressure feed paint cup and a method for using such liner. A lid is removed from the paint cup and a disposable liner bag is inserted into the cup while an open end of the liner bag extends from the open cup end. The open liner bag end is folded over and protects the cup end and paint is poured into the liner bag. A disposable lid is placed over the open cup end and the open liner bag end is folded inwardly over the disposable lid. The paint cup lid is then attached to the paint cup, clamping the liner bag and disposable lid in place. As the paint cup lid is placed on the paint cup, a paint feed tube is pushed through an opening in the disposable lid. Optionally, a ring may be placed in a recess in the disposable lid to retain the folded liner bag end in place while the paint cup lid is attached to the paint cup. After painting, the liner and any remaining paint are disposed of.

Abstract: A paint cup mounting arrangement including a mounting cylinder fastened to a paint spray gun by a screw joint, a socket sleeved onto the mounting cylinder and turned thereabout, a paint cup fastened to the socket by a screw joint, and a paint guide tube mounted within the mounting cylinder and the socket and sealed by rubber seal rings and adapted to guide paint from the paint cup to the paint spray gun, the paint cup being adjusted to a vertical position by turning the socket about the mounting cylinder.

Abstract: A multiple material spray system and method are provided for applying a spray by a single component spray gun. A first material is fed through a tube injector connected to an external port of the single component spray gun and a conventional fluid section feeds a second material through the single component spray gun without being exposed to the first material. A mixing area is positioned to receive the first and second materials outside of the single component spray gun so that these materials can be externally mixed immediately before applying a spray. The external mixing of the materials permits a spray of high viscosity, low VOC materials with fast gel times of approximately 20 to 40 seconds to be used because gelation in the single component spray gun is prevented by the external mixing. Also, the system and method reduce the number of components so that a more cost-effective process is achieved.

Abstract: For a rapid and simple assembly, the rotary atomizer of the coating arrangement described has a fastening pin (34) arranged on a valve unit (12). The fastening pin is inserted into a matching opening of a mounting flange (70) and is retained therein by a clamping device that exerts a force pressing the valve unit (12) against the flange (70). The atomizer is composed of individual modules (2,4,6,10,12) connected by screw connections and additionally comprises a rigid light guide rod for the transmission of optical rpm measuring signals, which remains in the valve unit (12) during disassembly of the atomizer.

Abstract: A system for spraying air-dryable liquid materials such as adhesives and paints and a method of using the system is disclosed. The system includes a hot air gun connected to both a source of hot pressurized air and a source of flowable liquid material. The gun includes a body having a handle assembly and a spraying assembly. The handle assembly includes a depressible trigger and first knob for adjusting the amount of liquid material in the spray and a second knob for adjusting the pattern of the spray. The spraying assembly includes a spray nozzle and control valves operably connected with the trigger for controlling the flow of pressurized hot air and liquid material. The spraying assembly also includes an air routing insert for routing air currents to the nozzle and a liquid material tube for routing liquid material to the nozzle. An air diverter assembly is also included for diverting an amount of heated air out of the front of the gun to aid in the drying of sprayed material.

Abstract: A spray gun assembly having a paint cup, a removable lid, a pivotable syphon tube unit rotatably secured to the lid and having an intake end located inside the paint cup, and a handle attached to the pivotable syphon tube unit exterior of the paint cup above the lid. The pivotable syphon tube unit is rotatable in the lid to permit manually positioning the intake end to the lower most region of the paint cup so that the intake end stays immersed in liquid when the spray gun assembly is tilted to a particular position.

Abstract: A hand held paint spray gun having a top mounted paint cup which extends from the rear of a gun body at an angle of 30.degree..+-.10.degree. to an axis about which the atomized paint is discharged. A retainer ring secures a lid on the cup. The lid seals to both the inside and the outside of the cup. The double seals reduce the risk of paint leakage. Preferably, the gun operates with suction paint feed which is augmented by gravity feed when paint in the cup is located above a nozzle assembly on the gun. To facilitate cleaning and to allow the gun to spray in an upward direction, the paint may be sealed in a collapsible closed bag located in the cup. With the closed bag and the suction feed, the gun will operate when aimed in all directions. The gun is easily cleaned by forcing solvent from the nozzle assembly back into the bag and disposing of the bag containing any remaining paint and the used solvent.

Abstract: A spray gun uses hot, high volume, low pressure (HVLP) air to atomize a coating material at a spray head of the gun. The coating material may be water-based adhesive or paint which may include a relatively small amount of solvent. The coating material may also be a high viscosity, solvent-based paint such as a polyester or urethane. The spray gun includes a plunger mechanism and a trigger which generate an air pressure control signal which opens a valve to allow the hot HVLP air to come to the front of the spray gun. Thermally insulated hot air hoses couple the spray gun to a source of hot air such as a heater conversion unit. Teflon tubes thermally insulate the coating material from the hot air as the coating material is received by the spray gun. A plastic shroud thermally insulates and concentrates a hot air coating material mixture during atomization of the coating material at a spray head of the spray gun. The hot air has a temperature in the range of 250.degree. F. to 350.degree. F.

Abstract: For an HVLP paint spray gun, an improved suction feed nozzle assembly including a fluid tip and an air cap. The air cap directs an annular flow of atomization air around a fluid discharge orifice formed by a tubular portion on the fluid tip to aspirate fluid from the orifice and to atomize the fluid. The air cap also directs pattern shaping air at the atomized paint. According to one feature of the invention, the spacing of the pattern shaping air orifices from the fluid discharge orifice is made sufficiently great that undue turbulence is not induced in the atomization air in the aspiration zone to maximize the fluid flow rate. According to a second feature of the invention, the fluid orifice in the fluid tip has a straight cylindrical portion and an expanding conical section connecting the cylindrical section to an annular flat front face of the tubular portion of the fluid tip.

Abstract: A spray nozzle member jets out paint in a fan-shaped pattern. Air streams are jetted from a conically annular center air nozzle in such a way as to surround the fan-shaped pattern, whereby a conically atomized spray pattern is discharged from a deformed opening. Notches formed on the deformed opening cause the conical pattern to spread, and fan-shaped air streams produced by air from auxiliary air nozzles promote the spreading of the spray pattern to a greater extent. Oblique air streams are forwardly supplied from side air nozzles into that pattern, so that a fan-shaped spray pattern is again produced. Paint under a pressure of several kg/cm.sup.2 is discharged from a spray nozzle. An atomizing air stream, except the part thereof corresponding to the edge of the fan-shaped spray, converges on the front extremely close to the spray nozzle. The atomizing air stream is discharged under a pressure of less than 2 kg/cm.sup.

Abstract: A spray gun with a powder spray nozzle sprays a pattern of coating material through specified discharge slot configurations to evenly coat a recess and/or the surface of a substrate. One discharge slot configuration, having two intersecting slots disposed at substantially sixty degree angles to each other, can be rotated to change the width of the coating being applied within the recess. The other slot configuration, having at least five radial slots and a substantially circular bore extending through the intersection of the slots, is effective to coat both the recess and the flat surface of the substrate.

Abstract: An electrically isolating pressure feed paint reservoir suitable for holding electrically conductive paint applied with an electrostatic spray gun. A paint container is located in an electrically insulated housing which is mounted on a dolly for portability. The housing also mounts a pneumatically operated paint pump for delivering pressurized paint to the spray gun. When a lid to the housing is removed the high voltage power source is turned off and any high voltage present in the housing is discharged through a resistor.

Abstract: A coating dispenser such as a spray gun, which is particularly adapted for the application of a protective coating material onto metal can bodies, comprises a gun body formed with a liquid passageway which carries the valve stem of a needle valve. In the presently preferred embodiment, the lowermost end or valve tip of the needle valve, and a valve seat, are carried within a valve seat block which is secured to the base of the gun body. A threaded connection is provided between the valve tip in the valve seat block, and the valve stem within the gun body, so that the valve tip, valve seat and valve seat block can be removed and replaced as a unit when the valve tip and/or valve seat become worn. Structure is also provided to exert a combined spring force and hydraulic force on the needle valve in order to quickly and efficiently move it from an open position to a closed position relative to the valve seat.

Abstract: A spray gun including a gun body having an air inlet channel, an air expansion chamber and an air distribution chamber. The air inlet channel and the air expansion chamber are interconnected by an orifice for achieving sonic velocities and reducing the pressure of the air. The air expansion chamber and air distribution chamber are interconnected by a distribution disc which allows the air to flow from the air expansion chamber into the air distribution chamber for distribution out of an air outlet nozzle at low pressure for atomizing paint.

Abstract: Single-piece manifold for use in pressurized painting equipment which is configured and arranged for joining a liquid inlet line, a pressure sensor, a filter, a pressure relief valve, and one or more liquid outlet lines by a streamlined network of passages in a compact and organized manner which eliminates static flow areas. The pressure sensor is assembled within the manifold in such manner as to avoid relative rotation between sensor components and thus avoid stressing electrical leads of the sensor.

Abstract: An improved shaft sealing ring for a portable paint gun of the type having an axially movable control shaft for controlling a supply of pressurized air to atomize a stream of paint. The sealing ring has a truncated frustro-conical surface tapering from a radially extending retaining surface toward a front end of the sealing ring and a radially extending flange at a back end of the sealing ring with an outer peripheral groove in an outer surface of the ring body between the flange and the retaining surface. The ring is installed by urging the front face through an opening having a diameter smaller than that of the face, the opening defined by a wall extending radially inwardly as a part of the gun housing. The flange is resiliently deflected to form a seal when the ring is installed. A central bore of the seal is sized to receive the shaft with a seal between the shaft and the ring provided by a ridge extending radially into the bore of the ring at the back end thereof.

Abstract: An airless spray nozzle which is capable of spraying paint of high viscosity as well as that of low viscosity while effectively preventing generation of tailing. A pair of stops formed between a substantially hemi-spherical depression of a front nozzle section and a through-hole of a rear nozzle section, a pair of main slants formed on the inner surface of the rear nozzle section defining the through-hole, a pair of first auxiliary slants and a pair of the second auxiliary slants each successively formed on the inner surface of the front nozzle section defining the depression cooperate to one another to positively spray paint of increased viscosity under a relatively low pressure without generating any tailing.

Abstract: It is filter structure for an air-spray gun, which includes a cylinder portion mounted between a push-button switch and the intake port of the air-spray gun. The cylinder portion includes a centrifugal filter, of which the upper end is mounted with a micro-filter chamber closely connected with the inlet of the push-button switch. The lower end of the centrifugal filter is mounted with a filtering cylinder and a water-guide plate. The moisture will be separated from the pressurized air when the pressurized air flows through the centrifugal filter. The moisture separated will flow into a water chamber, and will be drained off through a water-exhausting valve. After the pressurized air passes through the filtering cylinder, impurities in the air will be filtered out of the air, and then the air flows through a micro-filter chamber to separate any moisture from the air so as to let the pressurized air sprayed out of the gun contain no impurities and moisture at all.

Abstract: An improved fluid valve stem for an air spray gun has a triangular-shaped forward end extended into a cylindrical fluid outlet passage of a fluid nozzle. The triangular-shaped forward end forms liquid coating material flowing therepast into a hollow cylindrical stream that is emitted from the fluid nozzle and pneumatically atomized into a spray. The hollow stream of coating material is considerably easier to atomize than is a solid stream, so with the result that effective atomization is achieved at low air pressures and volumes for improved transfer efficiency.

Abstract: An electrostatic paint spray gun having built-in high-voltage generator that is cast into insulating material is improved in that the dielectric strength is increased in the region of that face of the insulating member that is adjacent to the charging electrode. In a first solution, the high-voltage cascade is cast such into the plastic member for this purpose that its high-voltage output is situated adjacent the input transformer, whereby a small plug tube for the stranded electrode lead is additionally co-cast into the insulating member parallel to the cascade. In a second solution, an annular gap is left free between the stranded electrode lead and the insulating member, is filled with insulating oil and is sealed with a seal.

Abstract: An improved control shaft seal and air valve for a portable paint gun with the seal having a radial clearance with the shaft except at a shaft sealing surface of limited axial length. The shaft seal has a conical surface radially outward of the shaft sealing surface to provide a sealing surface and also to provide transfer of axial forces at that surface to a radial direction to provide a force to urge the shaft sealing surface against the control shaft. A second conical surface of the seal provides for retention of the seal on an air valve spring when the paint gun is disassembled. An improved air valve for portable paint guns is also disclosed having a rigid axial hub and radial support carrying a relatively flexible rim portion adapted to engage a tapered seating surface in the gun.

Abstract: An airbrush with a fluid cup or the like which is removably retained on the airbrush and is adapted for containing and delivering fluids to be sprayed by the airbrush. The cup has a hollow reservoir portion and an attached tube portion. The reservoir portion is formed for retaining fluids disposed therein. The tube portion is non-concentrically fixedly attached at one end to a bottom of the reservoir portion and the end distal the reservoir removably inserts into a bore formed in the airbrush. The airbrush has a major axis running the length of the body and the bore in the airbrush is generally formed non-perpendicular to this major axis. The non-concentric mounting of the tube to the reservoir and the angle of the mounting bore permit the removable cup to be rotated within the mounting bore to remove it from the line of sight of a user.

Abstract: A coating material supply device in which coating material is pumped out at a predetermined flow rate and supplied at a constant flow rate to a coating machine. The device includes a plurality of double-acting reciprocal pumps, each having an inlet for the coating material supplied from a coating material supply source and an exit for discharging the coating material by the pressure of hydraulic fluid supplied at a constant flow rate from a hydraulic fluid supply source. The exits are connected to coating material selection valves connected in parallel with each other to the coating machine, and connected to switching valves that selectively switch the flow channel for the hydraulic fluid supplied from the hydraulic fluid supply source in response to the switching operation of the coating material selection valves.

Abstract: A fan-spray nozzle capable of preventing generation of tailing and improving spraying of paint, as well as being readily manufactured. In the nozzle, a through-hole of a cylindrical section is formed so as to have a cross-sectional area larger than that of a hemispherical depression formed in a dome section and at a front end thereof into a substantially elliptical or oval shape in cross section. The oval-shape has a minor axis portion formed so as to have a length equal to the diameter of the depression so that the through-hole may be smoothly connected to the hemispherical depression at the minor axis portion.

Abstract: A paint roller is provided with a removable sleeve receiving a cover having a pile on a stretchable flexible backing. A reversible, speed controllable pump on a hand cart provides paint to the roller from a supply under control of a switch at the roller handle. The roller handle contains a radio transmitter for transmission of pump control signals to a receiver in a pump housing mounted to the hand cart. A peristaltic pump is used for the pumping, and is reversible to facilitate draining of the system back to the paint source. Opening of a door on the pump housing releases pump roller pressure from pump tubing, provides access to pump rollers and pump tubing, and thereby facilitates installation and removal of the pump tubing. Conventional water hose fittings are provided to facilitate cleaning by connection to a hose bib of a domestic water system, if desired.

Abstract: A piezo-electric transducer type pressure sensor such as a silicon pressure sensor or the like is provided in a low path of fluid located in the midway between a valve section and a nozzle ejection port in a fluid ejection gun. When foreign matters in the fluid block the nozzle and hence the ejection from the nozzle becomes an abnormal condition, a fluid pressure variation produced in the flow path between the valve section and the nozzle ejection port is detected in the form of an electric signal by means of the piezo-electric transducer type pressure sensor.

Abstract: An apparatus (unit A) for completely and uniformly mixing different colored paints from a reservoir (unit B) is constructed from upper and lower sections (9) and (11). Different colored paints from reservoir (unit B) are supplied through lines (15) to inlet passageways (29) and (29c), which are in fluid flow communication with flow control valves (23) and (23c) and with corresponding fluid channels (37) spiraling around a generally frustoconically shaped protrusion (27) extending upwardly from the lower housing section (11). Protrusion (27) snugly engages within a correspondingly shaped cavity (25) formed in upper housing section (9), with the inside surface of the cavity cooperating with channels (37) to form individual passageways that crisscross each other to thoroughly mix the different colored paints carried therein. The passageways terminate at the upper end portion of protrusion (27) to discharge the uniformly mixed-together paint out through an outlet tube (5).

Abstract: An adaptor for utilizing disposable type containers of paint with a siphon-type spray paint gun wherein after the usual paint can that is attached to the commercially available spray paint guns is removed, the rapid placement and quick removal adaptor attaches to the spray gun siphon tube in a fixed configuration, the adaptor configured to receive and secure a disposable type container filled with paint in order that small paint jobs or touch-up painting may be accomplished more efficiently. The means by which the adaptor attaches to the spray gun siphon tube additionally includes a vent for venting the interior of the disposable can from which paint is removed for spraying.

Abstract: A self adjusting power supply for induction charging electrodes used in electrostatic spray coating apparatus is disclosed. A first resistance of high ohmic value is connected in series between a source of high direct current voltage and the induction charging electrode, while a second resistance is connected between the source of voltage and a ground reference point. The first resistance acts as a voltage divider with the spacial impedance which exists between the charging electrodes and ground in the spray nozzle of the spray coating apparatus, and serves to regulate the charging voltage and to compensate for variations in the conductivity of the material being sprayed. If the value of the spacial impedance should decrease for any reason, the increased current flow therethrough produces an increase in the voltage drop across the first resistance, thereby reducing and thus regulating the potential at the charging electrodes and serving to prevent corona and arcing within the spray gun.