WO2006053229A2

WO2006053229A2 - Electrostatic spray nozzle system

Info

Publication number: WO2006053229A2
Application number: PCT/US2005/040956
Authority: WO
Inventors: Steven C. Cooper
Original assignee: Mystic Tan, Inc.
Priority date: 2004-11-12
Filing date: 2005-11-12
Publication date: 2006-05-18
Also published as: ATE476257T1; AU2005304395B2; WO2006053229A3; HK1107956A1; AU2005304395A1; CA2597250A1; EP1817112A4; DE602005022755D1; AU2005304395A2; EP1817112B1; WO2006053229A8; EP1817112A2; WO2006053229A9

Abstract

An electrostatic spray nozzle assembly designed for optimum charge level over a wide range of liquid and air flow rates. The electrostatic spray nozzle assembly includes an adjustment mechanism operable to move a fluid tip assembly within a bore of a nozzle body so as to adjust a longitudinal distance between a liquid outlet of the fluid tip assembly and an outlet of a nozzle cap. The electrostatic spray nozzle assembly is mounted to a panel made of insulating material. The panel is adapted to accumulate an electrostatic charge having a same polarity as that of the coating composition dispensed during a spray operation. Further deposition of spray droplets onto the panel is prevented by electrostatic repulsion forces due to the accumulation of sufficient charge onto the surface of the panel from an initial deposit of a small volume of spray.

Description

ELECTROSTATIC SPRAY NOZZLE SYSTEM

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority from and incorporates by reference the entire disclosure of U.S. Provisional Application No. 60/627,191 filed November 12, 2004 and bearing Docket No. 32272-00153USPL and U.S. Provisional No. 60/627,480 file November 12, 2004 and bearing Docket No. 32272-00152USPL.

BACKGROUND OF THE INVENTION

TECHNICAL FIELD

This invention relates to electrostatic spraying nozzles. Specifically it relates to electrostatic spray nozzle systems utilizing induction charging or contact charging methods to apply static charge to atomized liquids operating in environments with untrained operators.

BACKGROUND

Electrostatic charging nozzles are well known and in widespread use in a number of commercial applications. Nearly every vehicle manufactured worldwide is painted electrostatically. Most of these industrial electrostatic spray systems charge spray by ionization and dispense powder or non-conductive liquids. There is a need for electrostatic spray devices that can reliably charge electrically conductive formulations, such as those that are water based. Several types of induction charging nozzles have been developed to produce electrostatically charged water sprays. U.S. Patent No. 4,004,733 to Law shows an induction charging nozzle having a conductive ring surrounding a liquid jet inside a channel where high velocity air impacts the liquid stream, thereby creating a fine spray. Commercial versions of the nozzle described in the Law patent have been manufactured with deviations that include a liquid tip made from an insulating material, upstream grounding of the liquid, and lengthening the electrode to near the full length of the atomization channel. These modifications have made the nozzle of U.S. Patent No. 4,004,733 reliable for use with water-based materials in most environments where the nozzle surfaces do not become excessively coated with conductive spray residue during a spraying operation. The conductive coatings on the surfaces of the nozzle can cause current leakage which reduces power supply voltage, damages surfaces, and reduces the internal charging field by elevating the voltage of the liquid

5 stream.

Further patents to Cooper and Law, U.S. Patent Nos. 5,704,554 and 5,765,761, utilize a fluid tip that is integral to the nozzle body, and utilize unique outside nozzle surface shapes to attempt to address some of the problems of stray electrical currents due to internal and external nozzle surface contamination. The fixed tip requires that the entire nozzle body be

I₀ replaced in the event of mis-manufacturing, damage or wear, thereby increasing the cost and the effort of nozzle maintenance. The electrode portion of these nozzles is permanently pressed into the retaining cover. This does not allow replacement of the electrode alone - the entire cover assembly must be replaced. U.S. Patent No. 4,343,433A to Sickles describes an induction charging nozzle with a fixed tip which utilizes air jets positioned around the main is spray jet to prevent nozzle surfaces from becoming coated by spray. This method requires a significant amount of additional air energy, and the fixed tip and fixed electrode do not allow for adjusting for wear, machining tolerance, or replacing individual parts.

A series of electrostatic nozzle patents, U.S. Patent Numbers 6,003,794, 6,138,922 and 6,227,466, to Hartman use an induction charging principle and liquid tip and air channel

2Q geometry that are similar to the above mentioned patents by Law, Cooper and Sickles. U.S. Patent No. 6,003,794 describes nozzles having many components with stacked tolerances. These nozzles have a replaceable electrode but do not allow for adjustment. The nozzles mentioned in the above-identified patents charge well when made to precise, but expensive, machining tolerances, use matched components and are operated within a narrow range of

25 liquid viscosities and liquid and air flow rates for a given internal spacing of components.

Variations in geometry of components causes charging variations which are due to improper droplet size or contact of the spray liquid with the walls of the induction electrode channel. Very small deviations in the internal spacing and dimensions of the atomization channel and liquid tip length have been observed to greatly diminish charging unless the air and liquid flows are within a narrow tolerance. These deviations occur due to nozzle manufacturing, from damage to components, and normal wear of components during use. Nozzle manufacturing deviations require that nozzle components be matched for optimal initial performance. This presents a problem since individual nozzle components wear over use and the entire nozzle often needs to be replaced with matching components. Measurements of spray charging from commercial versions of some typical nozzles with cost effective machining tolerances, but without using matched components, show over 30% variation from the same manufacturing run.

All of the above mentioned nozzles use air-atomizing induction-charging principles. With these nozzles the spray is charged to the opposite polarity as the electrode. Neither the liquid emitted from the tip nor the atomized spray is meant to contact the electrode. The advantage of such a system is that it produces high spray charging with very low electrode voltage and power. The disadvantage is that spray is attracted back to the nozzle surfaces. The wetted surfaces become conductive and reach the same polarity of the electrode, further attracting liquid spray droplets. The moisture deposits on the nozzle surface form into peaked shapes in response to the spray cloud space charge. The sharp points formed on these water droplets emit air ions that discharge large portions of the spray charge in the cloud. This effect can be minimized by adjusting the spray jet to a narrow column, using the air energy to force the spray a distance away from the nozzle. Another solution when this becomes a problem is to utilize contact charging principles. With contact charging types of nozzles the liquid stream is raised to a high voltage. This renders nozzle surfaces the same polarity as the spray cloud space charge and droplets are electrically repelled from the nozzle. The disadvantage is that the liquid container holding the spray liquid is also raised to high voltage, and as a result small containers should be used or isolation systems must be employed. Operation of electrostatic charging nozzles in situations where contact with the nozzle by humans is possible, such as in applications of spray booths used for sunless-tanning, presents additional safety considerations in their design. One consideration is in limiting the exposure by humans to the electrode itself during operation. Another consideration is the reduction of the amount of leakage current from any portion of the nozzle where human contact could be made. The previously mentioned nozzles by Law and Cooper use an electrode which is embedded between layers of plastic or ceramic. This is an effective method for reducing the chance of direct contact with the electrode. However, commercial versions of the nozzle of U.S. Patent No. 5,704,554 use an electrical contactor that is exposed when the cover is removed. This pointed contactor can be touched with the fingers and a shock can be received. The current from this contactor is in the range of 1 mA, capable of producing a shock intense enough to make the person involuntarily draw back very quickly and risk injury. Nozzles such as those described by Cooper and Law, Sickles, Hartman, and U.S. Patent No. 4,664,315 to Parmentar et al. are induction charging devices and have the unfortunate characteristic of attracting spray back to the nozzle itself. This causes wetting of the nozzle face. Wetting by conductive liquids, near the jet outlet, can cause a conductive bridge to form to the electrode and cause shock when these forward nozzle surfaces are touched, even though the nozzle parts are made from insulating materials. The nozzle of Hartman, which is mounted with the electrode through a hole in a PVC tube structure, is particularly susceptible to leakage currents forward from the electrode. After a period of use black electrical tracking lines are evident on the surface of the tube. In addition the thin electrode cover may be easily removed during use causing direct exposure to the electrode.

Accordingly, there is a need for an air-atomizing charging nozzle for conductive liquids that has adjustable components to allow tuning for optimized spray quality and charging levels for a wide range of liquid viscosities and flow rates. It is desirable that the nozzle be manufactured with cost effective machining tolerances and not require component matching. It is also desirable that these tuning adjustments can be made while the nozzle is operating. It is also desirable that these adjustments remain set in place during normal nozzle operation. In addition, it is desirable to be able to easily replace and interchange nozzle components without adversely affecting charging and spray quality. Furthermore it is desirable to have the option to use the same nozzle as a contact charging device when necessary. Safety design considerations dictate that the nozzle have reduced leakage currents on all nozzle surfaces, particularly those interior and exterior surfaces which are easily touched by untrained operators. Electrostatic charging of spray is well known in many agricultural and industrial processes. Electrostatic spray nozzles have been successfully developed to increase the deposition efficiency of powder and liquid formulations of agricultural pesticides, paints, and other coatings. Recently electrostatic spray devices have been developed for use by the consumer for applying cosmetics and for sunless tanning. A recent publication by the University of Georgia describes a method for applying decontamination sprays to humans utilizing electrostatic spray nozzles (See, Law and Cooper, 2002 Institute of Physics Conference, Edinburgh, Scotland UK).

Although electrostatic spray nozzles have been used for many years in a variety of applications, they are generally used in industrial environments with operators trained in the possible hazards associated with the high voltage devices. Electrostatic nozzles have not generally been used in consumer applications where the user is untrained and is unaware of any hazard. Many electrostatic nozzles are operated at voltage levels which can cause an electrical shock hazard. The hazard can come from contact with the high voltage electrode or from wetted nozzle surfaces which create conductive pathways to the high voltage electrode. The safety hazards may be due to contact with the electrical current itself, but more likely the hazard is the reaction to the shock, which may result in bodily harm from falling or contact with an object during involuntary movement away from the source of the shock.

Wetted or otherwise contaminated nozzle surfaces can cause diminished spray charging due to electrical leakage currents from the electrode to ground. These electrical currents, if excessive, may reduce power supply voltage causing reduced spray charge, hi induction charging types of nozzles, such as that of U.S. Patent Number 4,004,733 to Law modified with a dielectric twin-fluid tip and the invention of U.S. Patent Number 5,765,761 to Law and Cooper, leakage currents may contact the liquid stream and cause reduced charging by decreasing the electrical field between electrode and liquid. This problem is addressed in U.S. Patent Number 5,704,554 to Cooper and Law. In this nozzle an annular cavity surrounds the nozzle body and a cover to provide for reduced leakage currents. In addition, the liquid stream is insulated by providing a liquid tip which is an integral, non-removable part of the nozzle body. These aforementioned nozzles utilize an electrode embedded between layers of insulating material along the atomization channel. This design is safe from operator shock since the embedded electrode design prevents human contact with the electrode. However, gross contamination of the surfaces of these aforementioned nozzles can cause leakage currents from the embedded electrode to elevate the voltage of the upstream-grounded liquid stream. This reduces the internal electric field which is critical for proper induction charging. U.S. Patent Number 5,704,554 to Cooper and Law addresses solutions to internal and external electrical leakage to the liquid channel from the electrode, but does not address electrical contact from other sources such as from the high voltage connector at the rear of the nozzle. The wire connectors, once contaminated with conductive spray residues, create current pathways to the liquid connections at the rear of the nozzle. In some applications these nozzles have been mounted to panels, tubes or oscillating drums. The lack of a seal between the nozzle surface and the mounting surface causes spray residue to eventually cover both high voltage and low voltage sections of the nozzle. A series of patents to Hartman, U.S. Patent Numbers 6,003,794, 6,138,922 and

6,227,466, show a set of nozzles encased in a nonconductive tube. This device does not provide a barrier between the high voltage and low voltage sections of a nozzle system as evidenced by the design which has an electrode conductor in contact with the tube wall and penetrating through an opening in the tube. The design includes a non-insulated conductive air conduit and non-insulated conductive nozzle bodies within the tube shell that serve as conductors connected to the electrode voltage. Conductors to the electrode which extend through the tube and contact the exterior portion of the tube are covered on one face with a nozzle cap that does not provide an electrically tight sealing surface between inner and outer portions of the tube. The exposed conductors within the shell are in the vicinity of the liquid channels which are meant to be maintained at earth potential. The non-insulated high voltage air tube and nozzle bodies are likely to allow leakage currents to travel through threaded seams in the liquid channels. This effect will draw excessive electrode current, elevate the liquid electrical potential by contact and reduce charging. In addition, the non-insulated high voltage conduits may pose a significant hazard to those adjusting or maintaining the assembly while it is operating. hi commercial applications of the nozzle of US Patent 5,704,554 to Cooper and Law, where the nozzles are mounted to an oscillating drum for applications of sunless tanning liquids, the lack of a sealing surface on the nozzle eventually causes liquid to reach the inside of the drum. The presence of this conductive liquid inside the drum provides electrical leakage paths to the liquid channel of the nozzle. Electrical potentials on the liquid have been observed on commercial versions of this system to reach a level of over 80% of the induction electrode voltage. Conductive liquid tube fittings used on the rear of the nozzle accelerate this problem. Because the liquid is near the electrode potential rather than held at ground potential, the induction-charging electric field within the nozzle is greatly reduced, and spray charging is much less than necessary for electrostatic spray deposition. Once the nozzle surfaces have become contaminated they are very difficult to clean to the level necessary to prevent electrical leakage. Induction charging nozzles, such as those previously mentioned, also have the inherent drawback of spray being attracted back to the nozzle itself and to surrounding mounting fixtures. The electrode is of opposite polarity to the charged spray cloud. Once the dielectric nozzle surfaces become slightly wetted or otherwise conductive, the surfaces assume the electrode polarity and attract spray from the oppositely charged spray cloud. Excessive liquid returning to the nozzle not only contaminates the nozzle surface further, it causes spray cloud discharge as the liquid pulls into a peaked shape in the direction of the spray cloud space charge field. The point on the liquid droplet peak will produce air ions that can discharge an estimated 1/3 of the spray charge.

BRIEF SUMMARY OF THE INVENTION hi the air-atomizing induction-charging nozzles described above, the most important dimension that affects charging level and droplet size is the depth that the liquid tip penetrates into the atomization/electrode channel. Variations in this depth can be caused by dimensional variations in tip and air channel geometry. Manufacturing variations or normal wear of either of these parts can cause droplet size and charging variations, as well as cause the spray to be misdirected in the slipstream of the atomization channel. In contact charging systems using an air atomizer, the droplet size and charging level are also affected by these same geometries.

An electrostatic spray charging nozzle according to at least one embodiment of the present invention comprises a liquid tip that can be accurately axially moved and set during operation of the nozzle to optimize charging and spray quality in both induction charging and contact charging configurations, as well as to increase the useable range of liquid flow rates and to reduce the effects of normal manufacturing variations. In addition, the key components of the nozzle in accordance with embodiments of the present invention can be easily removed and interchanged with those of other nozzles without affecting charging or spray quality, hi one embodiment, the nozzle can be operated as a contact charging device by applying a voltage directly to the liquid. Li an alternate embodiment, the nozzle can be operated as an induction charging device where a voltage is applied to the air cap/electrode and the spray liquid is earthed (grounded) near the nozzle. In accordance with at least one embodiment the air cap/electrode is easily removed from the retaining cap for replacement or substitution for a cap of a different geometry.

An embodiment of the present invention is directed to an electrostatic spray charging nozzle having a nozzle cap having an outlet, a nozzle body having a first bore, and a fluid tip assembly extending at least partially through the first bore, the fluid tip assembly having a liquid inlet adapted to be connected to a source of liquid, and a liquid outlet adapted to dispense the liquid through the outlet of the nozzle body. The electrostatic spray charging nozzle further includes an adjustment mechanism operable to move the fluid tip assembly within the first bore so as to adjust a longitudinal distance between the liquid outlet of the fluid tip assembly and the outlet of the nozzle cap. Another embodiment of the present invention is directed to an electrostatic spray charging nozzle including a nozzle body having an air-channel bore; a nozzle cap having an outlet aligned with the air-channel bore, the nozzle cap adapted for removable coupling to a first side of the nozzle body; and a liquid inlet connector having a first end adapted to be coupled to a second side of the nozzle body, and a second end adapted to be connected to a source of liquid. The electrostatic spray charging nozzle further includes a fluid tip extending through the air-channel bore and having a fluid tip base adapted to be coupled to the first end of the liquid inlet connector, and a fluid tip outlet adapted to dispense the liquid through the outlet of the nozzle cap; and a conductive air cap having a bore aligned with the air-channel bore to receive the fluid tip outlet, the conductive air cap adapted to induce a charge to the liquid. The electrostatic spray charging nozzle still further includes an adjustment mechanism operable to move the fluid tip assembly within the air-channel bore so as adjust a longitudinal distance between the fluid tip outlet of the fluid tip and the outlet of the nozzle cap.

Another embodiment of the present invention is directed to an electrostatic spray charging nozzle having a nozzle cap having an outlet, a nozzle body having a first bore, and a fluid tip assembly extending at least partially through the first bore, and having a liquid inlet adapted to be connected to a source of liquid, and a liquid outlet adapted to dispense the liquid through the outlet of the nozzle body. The electrostatic spray charging nozzle further includes an adjustment mechanism operable to move the fluid tip assembly within the first bore so as to adjust an axial distance between the liquid outlet of the fluid tip assembly and the outlet of the nozzle cap.

An embodiment of the present invention comprises of an electrostatic charging nozzle having a sealing surface suited to mounting to an insulating panel. The sealing surface is to prevent liquid leakage and to electrically separate high voltage and low voltage components. The panel is charged to the same polarity as the spray cloud to reduce the amount of spray returning to the nozzle and surrounding surfaces, and block nozzle surfaces from becoming coated with conductive residues. The nozzle body is made from a non-conductive material so that it may be safely handled while operating. In addition, the present invention has a removable liquid tip to allow service to this key component of the nozzle while it is mounted to a panel. The nozzle system may be configured as a contact charging system by connecting the liquid directly to a high voltage source. Alternatively, the system may be configured as an induction charging device by energizing a conductive portion of the annular air cap, in a manner similar to that described by U.S. Patent Number 4,004,733 to Law. A sealing surface between nozzle and panel is provided to maintain a tight barrier preventing liquid contamination and electrical flow between sides of the panel barrier. The sealing surface may be on the nozzle body. This configuration allows disassembly of the nozzle from the spraying side of the panel. Alternatively the sealing surface may be on the nozzle cap. This configuration allows disassembly of the spray nozzle from the rear of the panel.

In accordance with an embodiment of the present invention an electrostatic spray nozzle mounted to a panel made of insulating material. In accordance with this embodiment, high voltage nozzle components are not in contact with the panel, and grounded portions of the nozzle are separated from high voltage portions of the nozzle by the panel. A seal on the nozzle surface prevents fluid leakage and the formation of electrical leakage currents to the opposite side of the panel. The insulating surface of the panel accumulates charge of the same polarity as the spray during the spray operation. Further deposition of spray droplets onto the panel is prevented by electrostatic repulsion forces due to the accumulation of sufficient charge onto the surface of the insulating panel from an initial deposit of a small volume of spray, hi accordance with an embodiment of the invention, the fluid tip is removable from either the front or the rear of the nozzle body while the nozzle remains mounted to the panel. The insulating panel further serves as a safety device by preventing ready access to high voltage components of the nozzle system. An electrostatic spray nozzle assembly in accordance with an embodiment of the present invention comprises a nozzle cap having a nozzle outlet, and a liquid tip assembly having a liquid inlet adapted to be connected to a source of coating composition, and a liquid outlet adapted to dispense the coating composition through the nozzle outlet of the nozzle cap. The electrostatic spray nozzle assembly further includes a nozzle body, a first side of the nozzle body adapted to be coupled to the nozzle cap, and an electrically insulating panel being positioned between the nozzle body and the nozzle cap. In accordance with an embodiment of the present invention the electrically insulating panel is adapted to accumulate an electrostatic charge having a same polarity as that of the coating composition dispensed during a spray operation. BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 is an exploded perspective view of one embodiment of the nozzle of the present invention shown disassembled to view the key components;

FIGURE 2A is a side view of the one embodiment of the nozzle of the present invention shown assembled;

FIGURE 2B is a section view of another embodiment of a nozzle of the present invention; FIGURE 2C shows a section view of the liquid tip area of the nozzle of FIGURE 2B;

FIGURE 3 shows one embodiment of the nozzle according to the present invention in which the fluid tip is removable from the front of the nozzle;

FIGURE 4 shows one embodiment of the nozzle according to the present invention in which the fluid tip is removable from the rear of the nozzle; FIGURE 5 shows a front view of the fluid tip of one embodiment of the present invention;

FIGURE 6 shows an embodiment of the nozzle according to the present with the addition of a non-conductive element to the inside of the retaining cap;

FIGURE 7 is a configuration for a tool to insert or remove the liquid tip in the nozzle according to the present invention;

FIGURE 8 shows components of a panel-mounted electrostatic nozzle system according to an embodiment of the present invention;

FIGURE 9 shows the nozzle system of an embodiment of the present invention mounted to the insulating panel by attaching the non-conductive nozzle body to the panel; FIGURE 10 shows an embodiment of the nozzle system of the present invention mounted to the insulating panel by attaching the non-conductive nozzle cap to the panel;

FIGURE 11 shows an embodiment of the nozzle system of the present invention with nozzles mounted to an oscillating drum; FIGURE 12 shows an embodiment of the nozzle system of the present invention with nozzles mounted to a dielectric panel such as may be used in a spray booth; and

FIGURE 13 illustrates a ball and socket mounting of the nozzle system according to an embodiment of the present invention to allow angular positioning of the spray.

5

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGURE 1, an embodiment of a nozzle of the present invention is illustrated in which a fluid tip 10 having a fluid tip base 20 with a threaded end is screwed into an inner threaded portion of a liquid inlet connector 30. In accordance with some

I₀ embodiments of the present invention, the fluid tip can be comprised of a dielectric material. A sealing boss 40 on the fluid tip 10 provides for liquid sealing between the fluid tip 10 and the liquid inlet connector 30. The liquid inlet connector 30 is further provided with fluid tip length adjustment threads 50 along an outer circumference. The liquid inlet connector 30 is adapted to be connected to a source of spray liquid. The fluid tip length adjustment threads 50 is are adapted to allow the liquid inlet connector 30 to be threaded into a back surface of a nozzle body 60. With the fluid tip 10 mounted to the liquid inlet connector 30, the selective threading of the liquid inlet connector 30 result in an adjustment in the axial/longitudinal positioning of the fluid tip 10 within a central air-channel bore 70 of the nozzle body 60.

In various embodiment of the present invention, the fluid tip 10 is a dual fluid tip that

2Q allows for the passage of air as well as a spray fluid. In an embodiment of the present invention, the fluid tip 10 is provided with air path cuts 75 in the sides which longitudinally extend to allow air to flow through the central air-channel bore 70 between the fluid tip 10 and the walls of the central air-channel bore 70. This allows for the passage of air while still allowing for concentric alignment of the fluid tip 10 with the central air channel. This design

25 improves air flow uniformity in the atomization channel and helps prevent spray contact with the channel walls. The directed air within the nozzle further produces a narrow directed spray which provides concentrated air energy at the jet outlet of the nozzle and greatly reduces the return of charged spray to the nozzle and nozzle mounting components. The nozzle body 60 is further provided with an air inlet 80 for providing a flow of air or other gas from an external source through to the central air-channel bore 70. An air cap 90 (or electrode) having a bore or channel is further positioned at a front end of the nozzle body 60 to form an atomization/electrode channel. An electrode wire 100 is provided to apply a charge to the air cap 90 when the nozzle is to be used for induction charging, and the air cap 90 is made from conductive materials. For a contact charging configuration, the spray liquid itself is raised to a high voltage and the air cap 90 may be made from insulating materials. In this configuration, the electrode wire 100 may be omitted. A nozzle cap 110 (or retaining cap) is further provided to retain the air cap 90 in the nozzle assembly. In accordance with some embodiments of the present invention, the nozzle cap 110 may be comprised of a hemispherical nozzle cap. In accordance with still other embodiments of the present invention, the nozzle cap may have alternate shapes. The nozzle cap 110 can be further provided with an aperture or recess adapted to removably receive the air cap 90. In accordance with an embodiment of the present invention the air cap 90 is adapted to rotate freely about the fluid tip assembly, and is removable for repair and/or replacement if necessary.

Adjustment of the depth that the fluid tip 10 penetrates into the atomization channel is made by turning the liquid inlet connector 30 attached to the back of the nozzle body 60. The thread pitch of the liquid inlet connector 30 determines the amount of axial/longitudinal movement that is provided with respect to the placement and positioning of the fluid tip 60 in the atomization/electrode channel for each turn of the liquid inlet connector 30. The threads of the liquid inlet connector 30 act as an adjustment mechanism such that the longitudinal or axial distance between the liquid outlet of the fluid tip 10 and the outlet of the nozzle cap 10 can be adjusted within a predetermined range.

The nozzle of various embodiment of the present invention allows for components of the nozzle to be removed and interchanged easily, for example for cleaning or replacement. The removable and interchangeable components of the nozzle include the fluid tip 10, the nozzle cap 110, the air cap 90, and the nozzle body 60. For example, it may be desirable to replace the air cap 90 with one having a larger bore in order to permit more air flow. It also may be desirable to replace the fluid tip 10 with one of different outside and inside diameters to provide different spray characteristics such as droplet size, spray pattern and spray volume. Nozzle cap 110 can be replaced to change its outside surface size and/or shape.

FIGURE 2 A illustrates a side view of one embodiment of a nozzle in accordance with the present invention shown in an assembled form. In the nozzle of FIGURE 2A, the nozzle

5 cap 110 is coupled to a front side of the nozzle body 60, and the liquid inlet connector 30 is coupled to a back side of the nozzle body 60. The nozzle of FIGURE 2A may be further provided with a spacer ring 120 placed between the nozzle cap 110 and the nozzle body 60. hi alternate embodiment of the nozzle of FIGURE 2 A, the spacer ring 120 may be removed for mounting of the nozzle to a panel.

I₀ FIGURE 2B shows a section view of another embodiment of a nozzle in accordance with the present invention. In this mounting configuration, he panel occupies the space previously occupied by the spacer ring 120. Adjustment of the length of the fluid tip 10 is made by turning a fitting on the liquid inlet connector 30 connected to the back of the nozzle. The thread pitch of the fluid tip length adjustment threads 50 of the liquid inlet connector 30 is controls the length of axial/longitudinal movement of the fluid tip 10 per turn. These fluid tip length adjustment threads 50 have been proven to seal the air very well even after many adjustment rotations have been made. The fluid tip 10 is shown inserted into the central air channel bore 70 of the nozzle body 60. The fluid tip 10 is held concentric in the air channel by ridges formed on the sides of the fluid tip 10.

2Q FIGURE 2C shows a section view of the fluid tip 10 area of the nozzle of FIGURE

2B. One aspect in accordance with embodiments of the present invention is that tightening the nozzle cap 110 pushes a ledge on the inside of the air cap 90 against a front face of the nozzle body 60 to cause a seal. This design reduces stacked tolerances seen in previous designs, since only the air cap 90 inside dimension need be made with tight tolerances and the nozzle

25 cap 110 and nozzle body 60 can be made with loose, non-critical tolerances. Any variation due to manufacturing of the nozzle parts can be taken out by adjusting the fluid tip 10 by turning the fitting of the liquid inlet connector 30 on the rear of the nozzle. By rotation of the fitting of the liquid inlet connector 30, the fluid tip 10 is made to move in an axial direction 95, thereby changing a length 105 of the fluid tip 10 that is exposed from the nozzle body 60, as well as a depth 115 that the tip end penetrates into the channel of the air cap 90.

FIGURE 3 shows one embodiment of the nozzle according to the present invention in which the fluid tip 10 is removable from the front of the nozzle assembly. This is accomplished by first removing nozzle cap 110, and then rotating fluid tip 10 to disengage the fluid tip 10 from the liquid inlet connector 30 while the liquid inlet connector 30 remains in place. Removal of the fluid tip 10 from the front is desirable in instances where the front of the nozzle is more accessible for maintenance. For instance, if the nozzle is panel mounted and closed in on the backside. The nozzle assembly of FIGURE 3 further illustrates the fluid tip base 20 of the fluid tip 10 as having threads 130 to facilitate removable of the fluid tip 10 from the liquid inlet connector 30. The nozzle assembly of FIGURE 3 is further provided with an electrode wire 100 to provide a high voltage to the spray liquid during a spraying operation.

FIGURE 4 shows one embodiment of the nozzle according to the present invention in which a fluid tip assembly 150 comprised of a fluid tip 10 and liquid inlet connector 30 is removable from the rear of the nozzle body 60. This is accomplished by rotating the liquid inlet connector 30 to detach the liquid inlet connector 30 from nozzle body 60 while the fluid tip 10 remains attached to the liquid inlet connector 30. In accordance with some embodiments of the present invention, the fluid tip can be comprised of a dielectric material. Removal of the fluid tip 10 from the rear of the nozzle body 60 may be desirable is some situations. For instance, if the nozzle were operating alongside other nozzles and only one nozzle needed service, the fluid tip 10 could be removed from the rear of the nozzle body 60 without interfering in the spray of the adjacent nozzles.

FIGURE 5 shows a front view of a fluid tip 10 of one embodiment of a nozzle body of the present invention. The fluid tip 10 is removable and inserted into the central air channel bore 70. Cuts along the length of the side of the fluid tip 10 allow air to flow evenly around a liquid outlet 160 of the fluid tip 10 and mate the tip concentric with the inner wall of the central air channel bore 70. The ridges formed on the length of the fluid tip 10 hold the fluid tip 10 concentric with the central air channel bore 70 of the nozzle body 60 and provide for air channels 170 through which air or another gas can flow. This arrangement improves the concentricity of the removable liquid tip 10 with the nozzle body 60 and the air cap 90. An electrode contactor 180 is provided in the case of induction charging nozzles where a conductive air cap 90 is used in order to couple a high voltage from electrode wire 100 to the air cap 90. The electrode contactor 180 includes a contact pad adapted to contact a surface of the air cap 90. In one embodiment of the present invention, the contact pad may be comprised of a spring-loaded contact pad. The electrode contactor 180 is recessed in a ring cavity 190 or channel of the nozzle body 60 to prevent touching with fingers while operating. The ring cavity 190 allows for the seating of air cap 90 as can also be seen in FIGURES 2B and 2C. Although the embodiment of FIGURE 5 is illustrated as having a ring cavity 190, it should be understood that in other embodiments a nozzle body can be used that does not have a ring cavity.

FIGURE 6 illustrates and embodiment of the present invention which includes the addition of a non-conductive element 200 to the inside of the nozzle cap 10 positioned between the ends of the retaining cap 110 and a top surface of the air cap 90. The function of the non-conductive element 200 is to increase human safety by reducing shock hazard at the nozzle tip area by providing an electrical isolation between the air cap 90 and the nozzle cap 110. The non-conductive element 200 further acts to reduce leakage currents from surfaces surrounding of the jet outlet 210 of the nozzle cap 110 that may be touched by human hands in certain applications. In accordance with various embodiments, the non-conductive element 200 is a non-conductive or substantially non-conductive disc. It is preferred that the non- conductive element 200 be a material with low electrical conductivity and low surface wettability, such as Teflon or UHMW Nylon. The addition of the non-conductive element 200 can be made without affecting any critical geometry or performance of the nozzle. The jet outlet hole 210 of the non-conductive element 200 is preferably made larger than the hole of the air cap 90 so as not to introduce any discontinuities along the wall of the air channel. Although the embodiment of FIGURE 6 is illustrated as having a non-conductive element 200, it should be understood that in other embodiments the non-conductive element 200 may be omitted. FIGURE 7 illustrates a configuration of a tool 220 used to insert or remove the fluid tip 10 in the nozzle according to the present invention. The tool 220 has an inside bore 230 of a similar shape as the outside of the sides of the fluid tip 10. The tool 220 is positioned over the fluid tip 10 such that a portion of the fluid tip 10 extends through the inside bore 230 of the tool 220. The tool 220 is then turned by hand to tighten or loosen the fluid tip 10 from the liquid inlet connector 30 as needed. An advantage provided by an embodiment of the tool 220 is that it contacts only the sides of the fluid tip 10 in order to prevent any damage to the liquid outlet end of the fluid tip 10.

Referring now to FIGURE 8, components of a panel mounted electrostatic spray charging system in accordance with an embodiment of the present invention is illustrated. These components are illustrated as suited for an air atomizing induction charging system. However, it should be understood that the system could be easily configured for contact charging by applying voltage directly to the liquid rather than an induction electrode. The main components of an induction charging system as shown include a nozzle body 310, removable liquid tip 320, an electrode retaining cap 330, an electrode air cap 340 having an air cap outlet 345, a sealing surface 350a, 350b on the nozzle body 310 and/or the electrode retaining cap 330, and an electrically insulating panel 360. hi accordance with various embodiments of the present invention, the electrically insulating panel is substantially electrically non-conductive. In accordance with various embodiments of the invention, the insulating panel may be made of a plastic material, hi a preferred embodiment of the invention, the insulating panel is made of an insulating material such that electrical resistance of the insulating panel to earth ground is greater than 2 Megaohms. The nozzle body 310 is preferably made from insulating material. The nozzle body 310 itself does not contain a fluid channel but instead includes a central air channel bore so that it allows the insertion of the removable liquid tip 320 in such a way that air from an air inlet 400 is caused to flow around the removable liquid tip 320 inserted into the central air channel bore, hi accordance with various embodiments, the removable liquid tip 320 is positioned into and held concentric with the central air channel bore. Preferably the central air channel bore is such that the removable liquid tip 320 may be inserted or removed from either the front or rear sides of the nozzle body 310. The air inlet 400 is adapted to receive a supply of air or other gas from a source. In various embodiments, the removable liquid tip 320 includes at least one air channel cut 325 (see FIGURES 9 and 10) along a length of the removable liquid tip 320 for allowing air to flow around a liquid outlet of the removable liquid tip 320. The insulating panel 360 is further provided with a plurality of mounting holes 365. In one embodiment of the present invention, the nozzle body 310 is fixedly mounted to the insulating panel 360 using mounting hardware that is coupled to the nozzle body 310 and passes through the mounting holes 365. In still another embodiment, the retaining cap 330 is mounted to the insulating panel 360 using mounting hardware that is coupled to the retaining cap 330 and passes through the mounting holes 365. In accordance with an embodiment of the invention, the mounting hardware can include bolts, screws, rods, attachment clips, etc. In still other embodiments of the invention, the nozzle body 310 and/or the retaining cap 330 can be affixed to the insulating panel 360 using an adhesive. The insulating panel 360 further includes a void 375 for allowing a portion of the nozzle body 310 to be mounted therethrough. In some embodiments of the present invention, a portion of the retaining cap 330 in contact with the insulating panel 360 is of a diameter such that the mounting holes 365 are covered by the retaining cap 330 to inhibit charge leakage through the mounting holes 365.

Still referring to FIGURE 8, the electrostatic spray charging system further includes a liquid inlet 370 adapted to be connected to a source of spray liquid and supply the spray liquid to the removable liquid tip 320. The electrostatic spray charging system still further includes an electrode wire 380 adapted to supply an electrostatic charge to the induction electrode air cap 340. The electrode retaining cap 330 is provided with an spray outlet 390 allowing for a spray of electrostatically charged liquid to be sprayed from the spray nozzle assembly.

At the beginning of a spraying operation, deposition of a small amount of spray on the surface of the insulating panel 360 causes the insulating panel 360 to be charged by accumulation to the same polarity as the spray cloud. As a result, during the remaining portion of the spraying operation the spray cloud is repelled from the insulating panel 360, resulting in a reduction in the amount of spray returning to the spray nozzle and surrounding surfaces, as well as blocking nozzle surfaces from becoming coated with conductive residues. The sealing surface 350a and/or the sealing surface 350b functions to prevent, or at least to inhibit, current flow between the electrode air cap 340 of the electrostatic spray nozzle assembly and a pathway to an electrical potential difference, such as a ground. The sealing surface 350a and/or the sealing surface 350b serves to prevent or inhibit the formation of charge leakage paths, the presence of which will inhibit optimal charging of the spray by the electrode air cap 340. The prevention or inhibition of current flow between the electrode air cap 340 and components of the electrostatic spray nozzle assembly that are positioned on the opposite side of the insulating panel 360 from the electrode air cap 340 provided by sealing surface 350a and/or sealing surface 350b also serves to isolate a person that may come in contact with these components from electrical shock. In various embodiments of the present invention, the spray is charged to a negative charge potential with respect to ground, whereas in other embodiments the spray may be charged to a positive charge value with respect to ground.

Referring now to FIGURE 9, a side view of an embodiment of the present invention in which a mounting of the nozzle by attaching the nozzle body 310 to the insulating panel 360 is illustrated. In this embodiment, a sealing surface 350a is located between the nozzle body 310 and the insulating panel 360, and may be fixedly mounted to the insulating panel 360. An example situation in which it maybe desirable to implement the embodiment of FIGURE 9 is in situations where it is desired to service the nozzle components from the spray outlet side of the insulating panel 360. In this case, removal of the nozzle cap 330 allows access to the removable electrode air cap 340 and the removable liquid tip 320. hi this embodiment it is preferable that the sealing surface 350a be a flat surface of the nozzle body 310 that contacts the insulating panel 360.

FIGURE 10 illustrates a mounting of the nozzle assembly in accordance with an embodiment of the present invention in which the nozzle cap 330 is attached to the insulating panel 360. This mounting configuration is useful when it is desired to have the serviceable components accessible from the rear of the insulating panel 360. One instance in which this may be desirable may be for use in a spray booth where a service door is provided on the rear of the spray booth. Another instance in which rear access is desirable is in a multiple-nozzle spray panel in which adjacent nozzles are continuously operating while an individual nozzle is serviced or its components are replaced or repaired. In the mounting scenario of FIGURE 10 it is desirable that the sealing surface 350b is on a flat area of the fixed nozzle cap 330 that contacts the insulating panel 360. FIGURE 11 illustrates an embodiment of the present invention in which a nozzle assembly is mounted on an oscillating spray nozzle drum 410. The nozzle drum 410 is mounted on a pivot axis 420 which allows the nozzle drum to oscillate during a spraying operation, which allows the nozzle drum 410 to be pivoted to create a sweeping spray effect, hi accordance with the embodiment of the invention of FIGURE 11, the outer surfaces of the nozzle drum 410 are constructed of electrically insulating material through which are mounted one or more nozzle assemblies each comprised of a nozzle cap 330 (or electrode retaining cap), an electrode air cap 340, a removable liquid tip 320, and a nozzle body 310. An example application of the embodiment of FIGURE 11 is for use in spray booths that provide for the application of sunless tanning media onto humans, hi an embodiment of the present invention, a sealing surface 350a may be provided between the nozzle body 310 and the mounting surface of the nozzle drum 410 and/or a sealing surface 350b may be provided between the nozzle cap 330 and the mounting surface of the nozzle drum 410. In still another embodiment, the nozzle system can be mounted either with the nozzle cap 330 or the nozzle body 310 providing the sealing surface. FIGURE 12 illustrates a multiple nozzle spray panel in accordance with an embodiment of the present invention such as may be used in a spray booth. The spray system of FIGURE 12 includes one or more nozzle assemblies each comprised of a nozzle cap 330, an electrode air cap 340, and a nozzle body 310, mounted to through the surface of an insulating plastic panel 430. A sealing surface may further be provided between the nozzle body 310 and the plastic panel 430 and/or between the nozzle cap 330 and the plastic panel 430. In still other embodiment of the present invention, the nozzle system can be mounted by the nozzle cap 330 or the nozzle body 310 depending on which side of the plastic panel 430 it is desired to have service access. FIGURE 13 illustrates a nozzle assembly mounted within a socket in an insulating (or non-conductive) panel. As illustrated in FIGURE 13, the nozzle assembly includes a nozzle cap 440 and a sealing surface 460 mounted on a first side of an insulating panel 360, and a nozzle body 470 mounted on a second side of the insulating panel 360. The nozzle cap 440 includes a jet outlet 450 which allows a spray of spray liquid to exit the nozzle assembly during a spraying operation.

The sealing surface 460 functions to prevent, or at least to inhibit, current flow between an electrode (not shown) of nozzle assembly and a pathway to an electrical potential difference, such as a ground. The sealing surface 460 serves to prevent or inhibit the formation of charge leakage paths, the presence of which will inhibit optimal charging of the spray by the electrode. The prevention or inhibition of current flow between the electrode and components of the electrostatic spray nozzle assembly that are positioned on the opposite side of the insulating panel 360 from the electrode provided by sealing surface 460 also serves to isolate a person that may come in contact with these components from electrical shock. In various embodiments of the present invention, the spray is charged to a negative charge potential with respect to ground, whereas in other embodiments the spray may be charged to a positive charge value with respect to ground.

This mounting arrangement allows the nozzle to pivot against the sealing surface 460 of the spherically-shaped nozzle to allow adjustment of the direction angle of the spray jet such that the nozzle can be set at a particular orientation. Position A of FIGURE 13 illustrates the nozzle assembly in which the jet outlet 450 has been rotated in an up position. Position B of FIGURE 13 illustrates the nozzle assembly in which the jet outlet 450 has been rotated in a midway position. Position C of FIGURE 13 illustrates the nozzle assembly in which the jet outlet 450 has been rotated in a down position. In various embodiments of the invention, the nozzle is pivotally mounted such that the side to side orientation of the nozzle can be changed. Although the embodiment of FIGURE 13 illustrates a nozzle body pivotally mounted within a socket of an insulating panel, it should be understood that other methods of pivotally mounting the nozzle body can be used such as using a pivot pin. Although various embodiments of the nozzle assemblies of the present invention have been illustrated as being mounted to a flat insulating panel, it should be understood that other panel shapes can be used. For example, the nozzle assemblies of the present invention may be mounted within a curved insulating panel or a faceted insulation panel. Although the various embodiments of the present invention have been described for use in the application of tanning solutions to a human subject, it should be understood that the present invention can also be applied to other cosmetic spray applications, as well as for the application of medicinal and decontaminant sprays, for example, antibiotics, antitoxins, disinfectants, sanitizers, etc. Further, although a preferred embodiment of the method and apparatus of the present invention has been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it is understood that the invention is not limited to the embodiment disclosed, but is capable of numerous rearrangements, modifications, and substitutions without departing from the spirit of the invention as set forth and defined by the claims.

Claims

WHAT IS CLAUSED

1. An electrostatic spray charging nozzle comprising: a nozzle cap having an outlet; a nozzle body having a first bore; a fluid tip assembly extending at least partially through the first bore, and having a liquid inlet adapted to be connected to a source of liquid, and a liquid outlet adapted to dispense the liquid through the outlet of the nozzle body; and an adjustment mechanism operable to move the fluid tip assembly within the first bore so as to adjust a longitudinal distance between the liquid outlet of the fluid tip assembly and the outlet of the nozzle cap.

2. The electrostatic spray charging nozzle of claim 1 wherein the nozzle body includes a first side adapted to be coupled to the nozzle cap.

3. The electrostatic spray charging nozzle of claim 2, wherein the nozzle cap is adapted for removable decoupling from nozzle first side of the nozzle body.

4. The electrostatic spray charging nozzle according to any of claims 1-3 further comprising: an air cap having a second bore aligned with the first bore, and positioned between the nozzle cap and the nozzle body so that the liquid outlet is received within the second bore.

5. The electrostatic spray charging nozzle of claim 4, wherein the nozzle cap includes an aperture adapted to removably receive the air cap.

6. The electrostatic spray charging nozzle of claim 4, further comprising: a substantially non-conductive element positioned between the nozzle cap and the air cap, the substantially non-conductive element including a jet outlet hole.

7. The electrostatic spray charging nozzle of claim 6, wherein the substantially non-conductive element comprises a Teflon disc.

8. The electrostatic spray charging nozzle of claim 6, wherein a diameter of the jet outlet hole is greater than a diameter of the air cap outlet.

9. The electrostatic spray charging nozzle of claim 4, wherein the air cap is formed of a substantially non-conductive material.

10. The electrostatic spray charging nozzle of claim 4, wherein the air cap is formed of a substantially conductive material.

11. The electrostatic spray charging nozzle of claim 4, wherein the air cap comprises an electrode adapted to induce an electrostatic charge to the liquid.

12. The electrostatic spray charging nozzle of claim 4, wherein the air cap is adapted to rotate freely about the fluid tip assembly.

13. The electrostatic spray charging nozzle of claim 4, wherein the air cap is adapted for mounting within a ring cavity of the nozzle body.

14. The electrostatic spray charging nozzle of claim 13 further comprising: an electrode contactor recessed within the ring cavity, the electrode contactor having a contact pad adapted to make electrical contact with a first surface of the air cap.

15. The electrostatic spray charging nozzle of claim 14, wherein the contact pad comprises a spring-loaded contact pad.

16. The electrostatic spray charging nozzle of claim 1, wherein the nozzle body includes an air inlet coupled to the first bore.

17. The electrostatic spray charging nozzle of claim 1, wherein the nozzle cap comprises a hemispherical nozzle cap.

18. The electrostatic spray charging nozzle according to any of claims 1-17, wherein the fluid tip assembly comprises: a liquid inlet connector having a first end adapted to be coupled to a second side of the nozzle body, and a second end adapted to be connected to the source of liquid; and a fluid tip having a liquid tip inlet adapted to be coupled to the first end of the liquid inlet connector, and a liquid tip outlet adapted to dispense the liquid through the outlet of the nozzle cap.

19. The electrostatic spray charging nozzle of claim 18, wherein the fluid tip comprises a dual fluid tip.

20. The electrostatic spray charging nozzle of claim 18, wherein the fluid tip is adapted for removal from the first side of the nozzle body.

21. The electrostatic spray charging nozzle of claim 18, wherein the fluid tip is adapted for removal from the second side of the nozzle body.

22. The electrostatic spray charging nozzle of claim 18, wherein the adjustment mechanism comprises a threaded coupling between the fluid tip and the liquid inlet connector.

23. The electrostatic spray charging nozzle of claim 18, wherein the adjustment mechanism comprises a threaded coupling of the first end of the liquid inlet connector to the second side of the nozzle body.

24. The electrostatic spray charging nozzle of claim 18, wherein the first end of the liquid inlet connector includes adjustment threads to facilitate the coupling of the first end of the liquid inlet connector to the second side of the nozzle body.

o 25. The electrostatic spray charging nozzle of claim 24, wherein the adjustment threads are adapted to adjust the longitudinal distance between the liquid outlet of the fluid tip and the outlet of the nozzle cap by rotation of the liquid inlet connector.

26. The electrostatic spray charging nozzle of claim 18, wherein the fluid tip is s adapted to be removable from the liquid inlet connector.

27. The electrostatic spray charging nozzle of claim 18, wherein the first bore comprises a central air channel bore and the fluid tip is adapted to be positioned into and held concentric with the central air channel bore of the nozzle body. 0

28. The electrostatic spray charging nozzle of claim 27, wherein the fluid tip further includes at least one air channel along a length of the fluid tip, the at least one air channel adapted to allow air to flow along the length of the fluid tip within the central air channel bore. S

29. The electrostatic spray charging nozzle of claim 18, wherein the adjustment mechanism comprises a frictional coupling between the first end of the liquid inlet connector and the second side of the nozzle body.

30. The electrostatic spray charging nozzle of claim 18, wherein the adjustment mechanism is adapted for adjustment of the longitudinal distance between the liquid outlet of the fluid tip and the outlet of the nozzle cap within a predetermined range.

31. The electrostatic spray charging nozzle of claim 18, wherein the adjustment mechanism is adapted for step-wise adjustment of the longitudinal distance between the liquid outlet of the fluid tip and the outlet of the nozzle cap.

32. The electrostatic spray charging nozzle of claim 18, wherein the fluid tip is comprised of a dielectric material.

33. The electrostatic spray charging nozzle of claim 1, wherein the adjustment mechanism is adapted to be threadedly coupled to the fluid tip assembly.

34. The electrostatic spray charging nozzle of claim 1, wherein the electrostatic spray charging nozzle is adapted to be mounted to a panel positioned between the nozzle body and the nozzle cap.

35. The electrostatic spray charging nozzle of claim 34, wherein the panel comprises an electrically insulating panel.

36. The electrostatic spray charging nozzle of claim 35, wherein the electrically insulating panel comprises a substantially electrically non-conductive panel.

37. The electrostatic spray charging nozzle of claim 1, wherein the first bore comprises a central bore.

38. The electrostatic spray charging nozzle of claim 1, wherein the first bore comprises an air-channel bore.

39. An electrostatic spray nozzle assembly comprising: a nozzle cap having a nozzle outlet; an electrode; a liquid tip assembly having a liquid inlet adapted to be connected to a source of coating composition, and a liquid outlet adapted to dispense the coating composition through the nozzle outlet of the nozzle cap; a nozzle body, a first side of the nozzle body adapted to be coupled to the nozzle cap; an electrically insulating panel being positioned between the nozzle body and the nozzle cap; and at least one sealing surface to inhibit current flow between the electrode of the electrostatic spray nozzle assembly and a pathway to a potential difference.

40. The electrostatic spray nozzle assembly of claim 39, wherein the electrically insulating panel comprises a substantially electrically non-conductive panel.

41. The electrostatic spray nozzle assembly of claim 39, wherein the electrically insulating panel is adapted to accumulate an electrostatic charge having a same polarity as that of the coating composition dispensed during a spray operation.

42. The electrostatic spray nozzle assembly of claim 39, wherein the spray nozzle further comprises: an air cap having an air cap outlet, the air cap being positioned between the nozzle cap and the first side of the nozzle body.

43. The electrostatic spray nozzle assembly of claim 42, wherein the air cap comprises an electrode adapted to induce a charge to the coating composition.

44. The electrostatic spray nozzle assembly of claim 42, wherein the air cap is adapted to be removable from the spray nozzle assembly.

45. The electrostatic spray nozzle assembly of claim 39, wherein the liquid tip assembly is adapted to be removable from the spray nozzle assembly.

46. The electrostatic spray nozzle assembly of claim 39, wherein the liquid tip assembly is adapted to be positioned into and held concentric with a central air channel bore of the nozzle body.

47. The electrostatic spray nozzle assembly of claim 39, wherein the liquid tip assembly further includes at least one air channel cut along a length of the liquid tip assembly, the at least one air channel cut adapted to allow air to flow around the liquid outlet.

48. The electrostatic spray nozzle assembly of claim 47, wherein the nozzle body includes an air inlet being adapted to provide the air to the at least one air channel.

49. The electrostatic spray nozzle assembly of claim 39, wherein the at least one sealing surface is positioned between the nozzle body and the electrically insulating panel.

50. The electrostatic spray nozzle assembly of claim 39, wherein the at least one sealing surface is fixedly mounted to the insulating panel and is adapted to provide a liquid seal between the nozzle body and the electrically insulating panel.

51. The electrostatic spray nozzle assembly of claim 39, wherein the at least one sealing surface is adapted to provide electrical isolation between the nozzle body and the electrically insulating panel.

52. The electrostatic spray nozzle assembly of claim 39, wherein the at least one sealing surface is positioned between the nozzle cap and the electrically insulating panel.

53. The electrostatic spray nozzle assembly of claim 39, wherein the at least one sealing surface is adapted to provide a liquid seal between the nozzle cap and the electrically insulating panel.

54. The electrostatic spray nozzle assembly of claim 39, wherein the at least one sealing surface is adapted to provide electrical isolation between the nozzle cap and the electrically insulating panel.

55. The electrostatic spray nozzle assembly of claim 39, wherein the electrically insulating panel comprises a nozzle mounting surface of a nozzle drum.

56. The electrostatic spray nozzle assembly of claim 55, wherein the nozzle drum is adapted for oscillatory movement about a pivot axis.

57. The electrostatic spray nozzle assembly of claim 55, wherein the nozzle drum is formed of an electrically insulating material.

58. The electrostatic spray nozzle assembly of claim 39, wherein the nozzle body is pivotally mounted to the electrically insulating panel.

59. The electrostatic spray nozzle assembly of claim 39, wherein the nozzle body is pivotally mounted within a socket of the electrically insulating panel.

60. The electrostatic spray nozzle assembly of claim 39, wherein the nozzle body is formed of a substantially electrically non-conductive material.

61. The electrostatic spray nozzle assembly of claim 39, wherein the electrically insulating panel includes a void adapted to allow a portion of the nozzle body to be mounted therethrough.

62. The electrostatic spray nozzle of claim 39, wherein the electrically insulating panel is adapted for fixed attachment to the nozzle body.

63. The electrostatic spray nozzle of claim 39, wherein the electrically insulating panel is adapted for fixed attachment to the nozzle cap.

64. The electrostatic spray nozzle of claim 39, wherein the electrically insulating panel is adapted for mounting the nozzle body at a particular orientation.

65. The electrostatic spray nozzle of claim 39, wherein the potential difference comprises a ground.