Abstract: Embodiments of the invention relate to a nozzle assembly for electrostatic deposition comprising a single point nozzle, the single point nozzle being conically shaped and including an apex and a circular base, the circular base including a smaller diameter cylindrical protrusion including a counter bore which connects to a passage leading to the apex; and a nozzle body, in contact with the single point nozzle and including a first through bore, a larger second through bore and a cross drilled port into the first through bore; and a cylindrical electrode, at least partially inserted within the first through bore of the nozzle body and in contact with the counter bore of the single point nozzle, the electrode including a bore mating aligned with the cross drilled port of the nozzle body, and inlets positioned at either end.

Abstract: A valve for controlling the flow of a gas or mixture of gases through a passageway in a coating material dispensing device includes first and second valve portions. The first valve portion is adjustable with respect to the second valve portion selectively to adjust the flow through the passageway. One of the first and second valve portions includes a first engagement member and the other of the first and second valve portions includes a second engagement member. Engagement of the first and second engagement members indicates the relative orientation of the first and second valve portions.

Abstract: A voltage block comprises first and second reservoirs and a switching device including an inlet port, an outlet port, a first reservoir port and a second reservoir port. The switching device is mounted in a third reservoir for movement between a first position and a second position. The third reservoir includes an electrically non-conductive fluid medium in which at least a portion of the switching device is immersed.

Abstract: A microdevice is constructed from a substrate having a microchannel formed therein and a cover plate arranged over the substrate. The cover plate in combination with the microchannel at least partially defines a conduit within the microdevice. The conduit has a surface that extends from an upstream region toward a downstream region and terminates at an opening. The microdevice also includes an annular lining that conforms to the conduit surface at the downstream region and extends from the opening toward the upstream region in the conduit. An emitter may be produced in situ by depositing an emitter material on the annular lining. In addition, material may be removed from the cover plate and/or substrate about the opening. As a result, an exterior microdevice surface is formed and a downstream portion of the emitter is exposed that protrudes from the exterior surface.

Abstract: An electrospraying apparatus and/or method is used to coat particles. For example, a flow including at least one liquid suspension may be provided through at least one opening at a spray dispenser end. The flow includes at least particles and a coating material. A spray of microdroplets suspending at least the particles is established forward of the spray dispenser end by creating a nonuniform electrical field between the spray dispenser end and an electrode electrically isolated therefrom. The particles are coated with at least a portion of the coating material as the microdroplet evaporates. For example, the suspension may include biological material particles.

Abstract: The mist ejection head includes: a nozzle which ejects liquid; a nozzle plate which has electrical conductivity and in which the nozzle is formed; a liquid chamber connected to the nozzle; an ultrasonic wave generating element which generates an ultrasonic wave applied to the liquid in a vicinity of the nozzle; and an electrode which is provided on a wall of the liquid chamber other than the nozzle plate, wherein an electric field applied between the nozzle plate and the electrode is controlled.

Abstract: A silicon die having an orifice layer with plural openings formed therein defines a drop ejection device for use in a handheld inhaler. An underlying control layer defines fluid chambers, each carrying a heat transducer. A control system energizes selected heat transducers to heat fluid in the chambers, vaporizing the fluid, which is ejected through the orifices in small droplets.

Abstract: A corona charge spray gun for dispensing powders for powder coatings. The spray gun includes a housing defining a chamber terminating in an outlet passageway. A high voltage electrode is mounted in the chamber spaced upstream of the outlet passageway and a ground electrode is mounted in the chamber spaced upstream from the high voltage electrode. The ground electrode is selected to have a surface area sufficiently larger than the surface area of the high voltage electrode in order to allow high voltages to be applied to the high voltage electrode without arch discharging occurring in the chamber. An inlet opens into the chamber for conducting a powder-gas mixture into the chamber and the electrodes receive cleaning gases for avoiding powder deposits on the electrodes.

Abstract: An electrostatic spray gun (10) having an air powered alternator-turbine (14) with a rotating impeller (24) therein mounted in bearings (18) is provided with bearings (18) which are coated with a solvent resistant material. This coating is provided on all surfaces of the bearing (18) except for the inner diameter (18A) which contains the impeller (24). This construction prevents leaching of the oil out of the bearing (18) and into the airstream and also is resistant to paint should the spray gun (10) become immersed in such.

Abstract: The invention provides an electrospray apparatus with an auxiliary electrode, and a method of using.

Abstract: A fuel injection assembly comprising a main structure (101) for mounting on an internal combustion engine, the main structure having one or more orifices (115) for injecting fuel directly into the combustion chamber of the internal combustion engine, and the main structure also having mounted thereon charge electrodes (105, 118) positioned to provide an electric field which passes through the flow of fuel, for charging fuel particles to improve atomisation. The main structure also has mounted thereon a spark electrode (104) adapted to provide a fuel ignition spark for the internal combustion engine. The main structure of the assembly is adapted for removable mounting, having a threaded portion (102) adapted to co-operate with a threaded aperture in the internal combustion engine, normally adapted to receive a convention spark plug.

Abstract: This Universal Flexible Powder Coating Tip/Nozzle (7) will greatly enhance the application of Powder Coating coverage in hard to reach area's do to the ability to bend the flexible tip/nozzle (7) & (10) to reach into those difficult to reach area's. The Powder Coater will no longer have to try to angle a large cumbersome powder Coating gun (1) into tight corners and openings, he only needs to insert the Universal Flexible Powder Coating Tip/Nozzle (7) into these hard to reach areas and bend and turn for proper angle. The uncharged Powder will flow down the Flexible tip/nozzle and receive charging as it travels past the contact at the powder Tip (9) & (10).

Abstract: A coating machine having a coating material discharging mechanism for discharging a previously filled coating material under pressure to an atomizing mechanism wherein a coating material bag for filling a coating material is housed in a coating material discharging chamber of a predetermined volume and an inlet/exit port of an operating fluid is disposed for exerting a pressure from the outside of the coating material bag thereby discharging the coating material under pressure, while crushing the coating material bag, whereby paint or other coating material can be discharged under pressure reliably by a small driving force.

Abstract: An electrostatic spray device and a cartridge for an electrostatic spray device that reduce the occurrence of electrically induced emulsion product separation are disclosed. The device and/or the cartridge may reduce electrically induced emulsion product separation by providing a conductive high voltage shield substantially around the product reservoir. Alternatively, the device and/or the cartridge may prevent the product located at the charging location from being in fluid communication with the product reservoir so that the product that is being charged cannot flow back into the product reservoir. The device and/or cartridge may alternatively reduce electrically induced emulsion product separation by minimizing the volume of product between the charging location and the exit orifice of the nozzle.

Abstract: A method and apparatus to improve the atomization of liquid and the efficiency of depositing liquid particles onto target objects, or to coat the target object with a thin film of liquid, to reduce the risk of high-voltage electrical shock, and to reduce the weight of an electrostatic spray system has been developed by inducing electrostatic charges onto the atomized liquid particles sprayed from a grounded metal nozzle.

Abstract: A coating machine 3 serving as a rotary atomizer comprises a hollow unrotary paint nozzle shaft 5 provided in the center of a motor shaft 10 serving as its rotary shaft. The paint nozzle shaft 5 is provided at a tip thereof with a gun-spray paint nozzle 5g and a gun-spray air nozzle 5f on the outside of the gun-spray paint nozzle 5g in the diametrical direction, and a needle shaft 21 is disposed in a paint passage 5b in the paint nozzle shaft 5 so as to serve as a valve mechanism for selectively supplying paint to either a bell cup 4 or the gun-spray paint nozzle 5g.

Abstract: A powder coating gun with an internal fan and a quick-change powder cartridge. Pressurized air generated by the fan entrains the powder coating material from the powder cartridge and the entrained powder coating material is charged in the ionizing field created by an emitter. The replaceable cartridge contains an inlet line and an outlet line oriented in a manner that allows the powder gun to be positioned in different angles and orientations with minimal risk of a powder spill from the powder coating gun. The powder cartridge contains a lid for supporting an inlet line and a body part constructed of clear or translucent material that allows the user to easily view the color of the powder. An electric power supply is used to power the fan and the emitter. A trigger is present in the handle of the powder coating gun and both controls the speed of the fan and enables the charge to the emitter.

Abstract: A nozzle hole of a conductive nozzle plate exposes the liquid surface of conductive ink. Ultrasonic generation means vibrates the ink for forming fine surface waves on the liquid surface so that the ink is sprayed from the nozzle hole as an atomized liquid particle group. A back plate provided on the opposite side of the nozzle hole in relation to a printing paper is supplied with a potential different from that for the nozzle plate, so that an electric field is formed therebetween. The sprayed liquid particle group is charged and hence urged by this electric field to adhere to the printing paper.

Abstract: An apparatus and method for droplet steering is disclosed herein. A throated structure having a nozzle defines a converging throat with an inlet and an outlet and a vectored fluid stream directed therethrough. The fluid stream is driven through the system via a vacuum pump. As the fluid approaches the outlet, its velocity increases and is drawn away from the nozzle through a connecting channel. As a droplet is ejected from a liquid therebelow, it will have a first trajectory until it is introduced to the high velocity fluid stream at the perimeter of the interior walls of the nozzle. The fluid accordingly steers the momentum of the droplet such that it obtains a second or corrected trajectory. Alternative variations include an electrically chargeable member, e.g., a pin, positionable to be in apposition to the outlet and capillary tubes for controlling the ejection surface of the pool of source fluid.

Abstract: The invention provides an apparatus, methods, and compositions for dispensing a fragrance onto laundry in a dryer without substantial loss of that fragrance during the drying process. The apparatus includes an electrostatic vapor generator capable of dispensing a fragrance composition into a dryer. The invention also provides electrostatically dispensable fragrance compositions containing glycols, vegetable oils, and perfumes. The invention further provides a kit and method for enhancing residual fragrance on laundry by adding a fabric conditioning composition and a fragrance composition in separate steps during the laundering process. The invention includes embodiments wherein the dispensation of the fragrance compositions is computer controlled.

Abstract: An external mix air assisted spray nozzle assembly having a nozzle body, and an air cap for a directing pressurized air streams on a discharging liquid stream external to the liquid discharge orifice of the nozzle assembly for atomizing and forming the liquid into the desired spray pattern. The air cap includes an upstream internal air chamber, an external, downstream liquid discharge and mixing chamber, and a central opening coaxial with the liquid discharge orifice communicating between the upstream and downstream chambers. The air cap further includes a plurality of angled pressurized air discharge passages which communicate with an annular plenum of the air chamber disposed in surrounding relation to the central opening for enabling substantially uniform particle breakdown and distribution at lower air pressures than heretofore possible.

Abstract: We have developed a gas distribution showerhead assembly, for use in a semiconductor processing chamber, which can be easily cleaned, with minimal chamber downtime. The gas distribution showerhead assembly includes an electrode having openings therethrough, and a gas distribution plate which includes a plurality of through-holes for delivering processing gases into the semiconductor processing chamber. The gas distribution plate is bonded to a first, lower major surface of the electrode. A removable insert which fits into an opening in the electrode through which gas flows. Spacing between surfaces of the removable insert and surfaces of the electrode is adequate to permit gas flow, but inadequate for plasma ignition within the opening. The removable insert can be easily removed during cleaning of the gas distribution showerhead, permitting the holes in the gas distribution plate to be easily accessed from both sides of the gas distribution plate.

Abstract: An apparatus for dispersing fluent material comprises a body defining a plurality of orifices arranged around a central axis and a charge injection device arranged on the central axis.

Abstract: The invention concerns a triboelectric sprayer for spraying electrostatic powder paint, comprising a powder intake, an air intake, a conduit transporting air and powder while providing the electrical charge of the powder and, in front of the charging conduit, means for emitting at least an air-powder mixture jet. The air intake is located in the axis of the charging conduit, while the powder intake is arranged laterally and converges in an acute angle with the air intake, in a point located upstream of the charging conduit. The air intake includes of an injector made of electrically conductive material which also constitutes an earthing member of the wall of the charging conduit.

Abstract: A powder spraycoating apparatus includes at least one compressed-air outlet (8) connected to a source (14) of compressed air from which it receives compressed air (15) at such a rate and such pressure that the compressed air at the compressed-air outlet (8) shall detach the powder's rim layer from the powder duct (4) and shall concentrate the powder flow toward the radial flow center and make it swirl, at a site near the downstream end (6) of the powder duct (4).

Abstract: A waterborne paint bell applicator is movable to and from a docking position and includes a paint receptacle connected to a paint canister. A paint filling station has a plurality of paint injectors each connected to a different color paint supply and being movable to the docking position for engagement with the paint receptacle for filling the paint canister with paint. A servomotor drives a piston in the canister.

Abstract: A coating-powder spray gun includes a gun housing (2) of which the front end face is sealed pressure-hermetically with respect to compressed gas by a front end wall (28). A current-limiting resistor (32) and at least a portion of a high-voltage generator (10) are potted in an integral electrically insulating block. The potted block may be received in the gun housing (2).

Abstract: A seal includes a first seal retainer, a seal holder and a second seal retainer. A somewhat cup-shaped recess of the first seal retainer opens in a first direction of motion of a movable member against which the seal is to seal. The seal holder includes a first somewhat cuplike portion adjacent to the first seal retainer and a second somewhat cuplike portion more remote from the first seal retainer. The first somewhat cuplike portion opens in a second direction of motion opposite the first. The second somewhat cuplike portion opens in the first direction. The second seal retainer includes a first portion closer to the seal holder and a second portion more remote from the seal holder. The second somewhat cuplike portion of the seal holder receives the first portion of the second seal retainer.

Abstract: An electrostatic powder coating apparatus including a housing with an interior coating area for receiving a workpiece. The interior coating area includes a vortex inducing surface and a pressurized air input device directs air against the surface to form a swirling pattern of air around the workpiece. A powder introducer directs charged powder into the swirling pattern of air and the powder is then electrostatically attracted to the workpiece. The powder introducer may be a powder fluidizing bed disposed in the housing or other suppliers, such as electrostatic powder spray guns. In alternative embodiments, vortex generators in the form of tubular structures connected proximate the housing inlet and outlet have tangential ports for introducing positive pressure air or inducing vacuum in the tubular structures.

Abstract: An apparatus is provided for manipulating droplets. The apparatus is a single-sided electrode design in which all conductive elements are contained on one surface on which droplets are manipulated. An additional surface can be provided parallel with the first surface for the purpose of containing the droplets to be manipulated. Droplets are manipulated by performing electrowetting-based techniques in which electrodes contained on or embedded in the first surface are sequentially energized and de-energized in a controlled manner. The apparatus enables a number of droplet manipulation processes, including merging and mixing two droplets together, splitting a droplet into two or more droplets, sampling a continuous liquid flow by forming from the flow individually controllable droplets, and iterative binary or digital mixing of droplets to obtain a desired mixing ratio.

Abstract: A powder spraying gun generates a desired pattern of electrostatically charged particles for coating a workpiece without rotating parts or particle deflectors. The powder pattern is generated with a funnel-shaped output in conjunction with air introduced into a powder charging chamber of the gun in a tangential swirling motion. The swirling air is additionally used to purge agglomerated powder particles from the charging electrodes in the charging chamber. The charging chamber surface is fashioned from material exhibiting low friction or high resistance to powder impact fusion.

Abstract: An electrostatic spraying device being configured and disposed to electrostatically charge and dispense a liquid composition from a supply to a point of dispersal, wherein the device comprises: a reservoir configured to contain the supply of liquid composition; a nozzle to disperse the liquid composition, the nozzle being disposed at the point of dispersal; a channel disposed between the reservoir and the nozzle, wherein the channel permits the electrostatic charging of the liquid composition upon the liquid composition moving within the channel; a high voltage power supply electrically connected to the power source; and a high voltage electrode electrically connected to the high voltage power supply, wherein a portion of the high voltage electrode is disposed between the reservoir and the nozzle, and wherein the high voltage electrode electrostatically charges the liquid composition within the channel at a charging location, wherein the nozzle pathway comprises an outlet path disposed adjacent to the nozzle

Abstract: An apparatus and method for manufacturing ultra-fine particles using an electrospray device is disclosed. One or more capillary provided at its tip with a nozzle is positioned within a guide duct and precursors such as metal organic materials and metal halogen compounds, or nonvolatile substances or volatile substances are supplied to the capillary. Voltages are applied to the capillary and the guide duct, respectively, so that a voltage difference is generated therebetween and the highly charged liquid droplets from the capillary are sprayed. The sprayed liquid droplets are carried along the guide duct together with carrier gas injected into the guide duct. When heat energy is applied to the liquid droplets, chemical reactions of the liquid droplets occur. A collecting plate positioned in front of the guide duct collects ultra-fine particles formed by the chemical reactions.

Abstract: A personal product comprising a liquid cosmetic composition and a hand-held electrostatic spraying device suitable for applying the composition to the human body, said hand-held electrostatic spraying device comprising a slit nozzle having a maximum width of from 0.05 mm to 0.5 mm, means for containing the liquid cosmetic composition, means for supplying the liquid cosmetic composition to the nozzle, an electricity source, high voltage circuitry arranged so that, in use, liquid cosmetic composition sprayed in atomised form from the nozzle is electrically charged, and control means for selectively applying a high voltage.

Abstract: A coating material dispensing device includes a port adapted to be coupled to a source of coating material, an actuator for controlling a flow of compressed gas through the dispensing device, and a valve coupled to the actuator to be controlled by the actuator. The valve includes a valve housing, a valve closure member, and a valve seat. The valve closure member is movable in the housing under the control of the actuator between a closed position against the valve seat and an open position away from the valve seat. An inlet port is provided into the housing. The inlet port is oriented on a first side of the valve seat. The inlet port is adapted to be coupled to a source of the compressed gas. An outlet port is provided on the second side of the valve seat.

Abstract: The paint-spraying apparatus exhibits a supply line 7 for coating material, extending from the color changer to the atomizer. Cut-off valves 26, 27 installed in the supply line delimit an insulating section 25 of said supply line, which insulating section is associated with means 28 to 32 for emptying and flushing said insulating section 25. A voltage divider 16 is connected in parallel to said insulating section 25. When colors are changed, the residual coating material present in said voltage divider 16 can be moved into the empty insulating section 25, after which it is forced by means of slugs back through the entire supply line 7 to the color changer 1, and is thus reclaimed.

Abstract: A method of manufacturing a liquid medium containing composite ultrafine particles comprises the steps of preparing a dispersion medium that is a liquid medium in which ultrafine particles of different materials from each other are dispersed, introducing the dispersion medium into first and second chambers, respectively, applying high frequency voltage to the chambers and exciting dispersion media, applying direct current voltage to each dispersion medium on the downstream side than the applying position of the high frequency voltage and electrifying these in different polarities from each other, and aggregating/bonding by means of excitation transfer as well as electrostatically aggregating ultrafine particles each other in the liquid medium in the crashing field by injecting the dispersion media electrified in different polarities from each other through two nozzle sections at a high speed, and crossing/crashing each other.

Abstract: A coating material dispensing device includes an output port through which the coating material is dispensed and an electrode projecting from the dispensing device adjacent the output port for transferring electrical charge to the coating material dispensed through the output port. The coating material dispensing device further includes a shield for shielding a portion of the electrode adjacent the electrode's connection to the dispensing device.

Abstract: For improving external charging in electrostatic atomizers for conductive coating material and for reducing the structural size of the atomizer, particularly for robot applications, the charging electrodes are embedded in a ring part made of insulating material, which is set directly on the outside of the outer housing or forms a part of the outer housing.

Abstract: Apparatus for the electrostatic powder paint spray coating of substrates, such as automotive vehicles, is provided. The apparatus includes modular applicators which are mountable into a programmable, robotically controlled housing. The modular applicators are switchable into and out of an operational mode on command, to facilitate different optimal coating procedures for coating differing surfaces, ranging from large, open surfaces to smaller, highly irregular substrate surfaces. The applicator heads may be spatially switchable on command from, for example, a bell cup spray applicator to a spray gun applicator. Flow control to each applicator is preferably enhanced using selectable pneumatically controlled pinch valves.

Abstract: A high-speed rotary atomiser for applying powder coating includes a housing together with a rotatable bell disc arranged at the front of housing A guidance air arrangement in the form of a rotationally symmetrical air guidance body coaxial to bell disc is provided for shaping the powder cloud generated by the high-speed rotary atomizer, which air guidance body is mounted on the front of housing. Air guidance body has a jacket surface to which guidance air be so supplied that it flows forwards along jacket surface as a substantially rotationally symmetrical air curtain along jacket surface. The air curtain flowing over the jacket surface of air guidance body impinges on the powder cloud generated by bell disc and shapes it according to the quantity and velocity of the air curtain and according to the geometry of air guidance body.

Abstract: An electrostatic spraying device being configured and disposed to electrostatically charge and dispense a product from a supply to a point of dispersal. This device has a reservoir configured to contain the supply of product and a nozzle to disperse the product. A channel is disposed between the reservoir and the nozzle, wherein the channel permits the electrostatic charging of the product upon the product moving within the channel. A positive displacement mechanism is used to move the product from the reservoir to the nozzle. A portion of the high voltage electrode being disposed between the reservoir and the nozzle is used to electrostatically charge the product within the channel at a charging location. A mixing mechanism may be disposed between the reservoir and the nozzle to reconstitute any product which may have separated. The high voltage contact may be spring biased in direction towards the high voltage electrode.

Abstract: The transformer (16) in the power supply (14) of an electrostatic spray gun (12) is designed to start saturating before the maximum desired output current is reached. During saturation, as the transformer secondary current goes up, the output voltage goes down, thus obtaining the desired output load line with much less tip resistance. Since the transformer (16) was designed to saturate earlier, it was also smaller in size. This reduced overall size and weight of the gun (12) compared to prior art power supplies have larger transformers and tip resistors.

Abstract: A minute droplet forming apparatus comprises a nozzle 1 for storing therewithin a liquid 2 for forming a droplet 3; a substrate 5, disposed so as to face the tip of the nozzle 1, for mounting the droplet 3 dropped from the tip of the nozzle 1; and a pulse power supply 10 for applying a pulse voltage between an electrode 12 arranged in the liquid 2 within the nozzle 1 and the substrate 5. After a liquid column 2a is formed by projecting the liquid from the nozzle tip by applying the pulse voltage between substrate 5 and the electrode 12, a nickel piece 7 disposed within the nozzle 1 is moved to the tip part of the nozzle 1 by an XYZ stage 9 by way of a magnet 8, so as to enhance the fluid resistance in the nozzle tip part, thereby causing a setback force for returning the liquid 2 into the nozzle 1, by which the droplet 3 is isolated from the liquid column 2a.

Abstract: The invention provides a sprayer for spraying mold wall treatment agent or another liquid. The liquid is sprayed onto, for example, the walls of a mold or some other article. The sprayer includes a spray element body and a rotor mounted with freedom to rotate around an axis of rotation in the spray element body. An atomizing element is attached to one end of the rotor. A first feed line for mold wall treatment agent or another liquid to be sprayed is provided, as well as a second feed line for control air which directs mold wall treatment agent atomized by the atomizing element in the desired spray direction.

Abstract: Fluids are atomized using a miniaturized electrostatic microinjector. The microinjectors are capable of producing uniform droplets in several spray modes, and metering and dispersing very small volume fluids. The atomizer is useful in carburetion systems for internal combustion engines, to prepare samples for analytical methods such as MALDI, for fluid filtration and separation, and in other applications.

Abstract: An improved Electrohydrodynamic (EHD) nozzle particularly suitable for a handheld pulmonary aerosol inhaler increases the consistent and efficient dispensing of therapeutic liquids by reducing or eliminating wetting through shielding of discharge electrodes. Some versions further eliminate wetting while enhances neutralization of the aerosol through presentation of a corona wind of ions annularly surround the aerosol. Incorporation of improved liquid distribution with consistent pressure drops to each EHD nozzle tip allows horizontal dispensing, and by using dielectric nozzle tips with low surface energy to thereby avoid wicking between dispenses and to advantageously reduce achievable particle size when dispensing. Some versions feature enhanced snap-fit assembly and other manufacturability advantages. One of the unique features of the EHD nozzles is achieved high dose rate (microliters/minute) with low wetting and small particle size (1.0-5 microns), although these properties tend to be mutually exclusive.

Abstract: An electrostatic spray gun (10) having an air powered alternator-turbine (14) with a rotating impeller (24) therein mounted in bearings (18) is provided with bearings (18) which are coated with a solvent resistant material. This coating is provided on all surfaces of the bearing (18) except for the inner diameter (18A) which contains the impeller (24). This construction prevents leaching of the oil out of the bearing (18) and into the airstream and also is resistant to paint should the spray gun (10) become immersed in such.

Abstract: A display (K) on the back (14) of the spray gun (12) informs the electrostatic gun operator of the tip voltage and tip current This information is used to quickly verify system operation and paint resistivity. The painter can monitor the light bars (K) for proper operation while painting.

Abstract: An electrostatic spray gun apparatus includes a spray gun housing and a nozzle attached to a spray end of the housing, and a powder path that extends in a substantially straight line along an axis of the housing from the powder inlet to the powder outlet. The powder path is in the form of an enclosed smooth powder passage that is substantially continuous and uninterrupted from the powder inlet to the powder outlet to eliminate substantially all recesses or gaps that could capture or trap powder. The powder passage is formed by a plurality of tubular segments that are aligned along the housing axis and abut end to end, that when assembled in the housing axially compress the segments together to substantially eliminate dead spots or recesses to form the continuous smooth powder path. A gun purge function is provided that allows a purge line to be installed on the gun assembly. A cartridge valve and conductor assembly is provided between the gun electrode in the nozzle and the output of the voltage multiplier.