Abstract:
A spraying system for delivering a plurality of fluids for applying to a surface is disclosed. The spraying system includes a nozzle assembly having a fluid tip, a body with a central orifice and a set of orifices radially adjacent to the central orifice, an air cap having a set of passages in communication with a set of orifices and a set of conduits contained at least partially within the set of passages, and a plurality of fluid circuits in communication with the nozzle assembly. One of the fluid circuits is adapted to deliver an adhesive, one of the fluid circuits is adapted to deliver an activator, one of the fluid circuits is adapted to deliver atomization air, and one of the fluid circuits is adapted to deliver fan air from the nozzle assembly. The spraying system also includes a controller that can be switched to an active state upon a which the fluid circuit for atomization air and the fluid circuit for fan air are opened essentially simultaneously, the fluid circuit for the activator is opened and then the fluid circuit for the adhesive is opened, and to an inactive state, upon which the fluid circuit for the adhesive and the fluid circuit for the activator are closed essentially simultaneously, and the fluid circuit for atomization air and the fluid circuit for fan air are closed essentially simultaneously. The adhesive is delivered in a generally axial direction through the central orifice in the body, atomization air to atomize the adhesive is delivered in a generally axial direction through the set of orifices in the body, fan air is delivered into the set of passages in the air cap and in a generally radial direction from the set of orifices in the air cap, and the activator is delivered into the set of passages in the air cap from the set of conduits so that the activator is atomized by fan air within the set of passages in the air cap and delivered from the set of orifices of the air cap, so that a fluid mixing area is provided outside the nozzle assembly in a space ahead of the orifices through which the adhesive and atomization air are delivered.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to a fluid spraying system adapted for use within a work environment. In particular, the present invention relates to a fluid spraying system configured to discharge an adhesive on a surface to be coated. 
     BACKGROUND OF THE INVENTION 
     It is well known to deliver fluids, such as adhesives, from a spraying system for various purposes. Such known spraying systems are disclosed, for example in U.S. Pat. No. 5,419,491 issued to Breitsprecher on May 30, 1995 titled TWO COMPONENT FLUID SPRAY GUN AND METHOD and in U.S. Pat. No. 5,639,027 issued Jun. 17, 1997 to Fritz titled TWO COMPONENT EXTERNAL MIX SPRAY GUN. Such known spray systems include using air pressure to propel or convey one fluid component and air to propel another fluid component. The two components are mixed and applied to a surface to be coated with the fluids. 
     One such known spraying system includes a two component external mix spray gun that requires a pneumatically operated valve for delivering a catalyst into pattern shaping air passages in the barrel of the gun. The valve opens in response to pressure created by opening a unitary chamber for a pattern shaping air passage and an atomization air passage. Before opening an adhesive fluid valve for delivering an adhesive of such known gun, a manual trigger operates air valves to provide atomization air and the pattern shaping air. The valve is then opened (prior to the opening of the adhesive fluid valve) in response to an increase in air pressure downstream from the air valves (i.e., in response to the operation of the trigger and the presence of the flow of the pattern shaping air) to inject the catalyst into pattern shaping air passages. Then, external to such known spray gun, the catalyst is brought into contact with the adhesive, which is “atomized” by the atomization air and the pattern shaping air. However, a problem with such known guns is that the manual trigger may not fully open the adhesive fluid valve, which may result in an inconsistent and ineffective ratio of the catalyst to the adhesive and “clogging” of the gun. 
     Another known spraying system includes an air-operated fluid spray gun for mixing multiple fluids together almost simultaneously to deposit the mixture on a surface. Such mixing and deposition is accomplished by first directing an atomized stream of adhesive fluid axially out of the end of the barrel of the gun and toward the surface to be coated. An atomized stream of activator fluid is then injected generally radially into the adhesive stream so that the activator and adhesive streams mix thoroughly and the mixture is almost simultaneously deposited on the surface. In such known spray guns, the activator fluid is discharged from fluid nozzles. However, a problem with such known spray guns is that the activator is turned on before the adhesive is turned on, which may result in an incorrect ratio of a volume of adhesive to a volume of activator fluid and “clogging” of the gun. 
     Accordingly, it would be advantageous to provide a fluid spraying system that provides for the independent control of the flow of the various fluids. It would also be advantageous to provide a fluid spraying system that provides for improved atomization of the activator fluid, for example with fan air within the fan air passages of an air cap. It would further be advantageous to provide a fluid spraying system that is intended to be simple to assemble, maintain and service. It would also be advantageous to provide a fluid spraying system that provides a suitable ratio of activator to adhesive. Other advantages of the subject matter recited in the claims will become apparent to those skilled in the art upon review of the specification and the appended claims. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a spraying system for delivering a plurality of fluids for applying to a surface. The spraying system includes a nozzle assembly having a fluid tip, a body with a central orifice and a set of orifices radially adjacent to the central orifice, an air cap having a set of passages in communication with a set of orifices and a set of conduits contained at least partially within the set of passages, and a plurality of fluid circuits in communication with the nozzle assembly. One of the fluid circuits is adapted to deliver an adhesive, one of the fluid circuits is adapted to deliver an activator, one of the fluid circuits is adapted to deliver atomization air, and one of the fluid circuits is adapted to deliver fan air from the nozzle assembly. The spraying system also includes a controller that can be switched to an active state upon a which the fluid circuit for atomization air and the fluid circuit for fan air are opened essentially simultaneously, the fluid circuit for the activator is opened and then the fluid circuit for the adhesive is opened, and to an inactive state, upon which the fluid circuit for the adhesive and the fluid circuit for the activator are closed essentially simultaneously, and the fluid circuit for atomization air and the fluid circuit for fan air are closed essentially simultaneously. The adhesive is delivered in a generally axial direction through the central orifice in the body, atomization air to atomize the adhesive is delivered in a generally axial direction through the set of orifices in the body, fan air is delivered into the set of passages in the air cap and in a generally radial direction from the set of orifices in the air cap, and the activator is delivered into the set of passages in the air cap from the set of conduits so that the activator is atomized by fan air within the set of passages in the air cap and delivered from the set of orifices of the air cap, so that a fluid mixing area is provided outside the nozzle assembly in a space ahead of the orifices through which the adhesive and atomization air are delivered. 
     The present invention also relates to a method to for controlling the fluid circuits in a spraying system for delivering a plurality of fluids for applying to a substrate. The method includes switching a controller to an active state upon a which a fluid circuit for atomization air and a fluid circuit for fan air are opened, opening a fluid circuit for activator and opening a fluid circuit for an adhesive, activating the adhesive with the activator, spraying the activated adhesive on a surface, switching a controller to an inactive state upon which the fluid circuit for the adhesive and the fluid circuit for the activator are closed, purging the system with fan air and atomization air, and closing the fluid circuit for the atomization air and the fluid circuit for the fan air. 
    
    
     DESCRIPTION OF THE FIGURES 
     FIG. 1 is a fragmentary perspective view of a fluid spraying system according to an exemplary embodiment of the present invention showing a portion of an adhesive fluid circuit, a fan air fluid circuit and an atomization air fluid circuit. 
     FIG. 2 is a perspective view of the fluid spraying system of FIG. 1 showing a portion of the atomization air fluid circuit, a cylinder air fluid circuit and an activator fluid circuit. 
     FIG. 3 is an exploded perspective view of the fluid spraying system of FIG. 1 according to an exemplary embodiment of the present invention. 
     FIG. 4 is a cross-sectional view of the fluid spraying system of FIG. 1 taken along line  4 — 4  of FIG.  2 . 
     FIG. 5 is a fragmentary cross-sectional view of an activator block, a secondary block and a flow control assembly taken along line  5 — 5  of FIG.  4 . 
     FIG. 6 a fragmentary cross-sectional view of the flow control assembly. 
     FIG. 7 is fragmentary a cross-sectional view the flow control assembly taken along line  7 — 7  of FIG.  6 . 
     FIG. 8 is a fragmentary cross-sectional view the fluid spraying system of FIG. 1 taken along line  8 — 8  of FIG.  4 . 
     FIG. 9 is a fragmentary cross-sectional view of a body, a nozzle assembly and an air cap assembly of the fluid spraying system of FIG. 1 taken along line  9 — 9  of FIG.  4 . 
     FIG. 10 is a schematic diagram of the electronic circuitry of the fluid spraying system. 
     FIG. 11 is a fragmentary perspective view of the air cap assembly. 
     FIG. 11A is a fragmentary cross-sectional view of the air cap assembly taken along line  11   a — 11   a  of FIG.  11 . 
     FIG. 11B is a fragmentary cross-sectional view of the air cap assembly taken along line  11   b — 11   b  of FIG.  11 . 
     FIG. 12 is an exploded perspective view of the activator block and the secondary block. 
     FIG. 13 is an exploded perspective view of the piston assembly. 
     FIG. 14 team is a flow chart of the sequence in which the fluid circuits of the fluid spraying system are turned on and off. 
     FIG. 15 is a fragmentary perspective view of a fluid spraying system according to an alternative embodiment of the present invention. 
     FIG. 16 is an exploded perspective view of the fluid spraying system of FIG.  15 . 
     FIG. 17 is a cross-sectional view of the fluid spraying system of FIG. 15 taken along line  17 — 17  of FIG.  15 . 
     FIG. 18 is a perspective view of a barrel of the fluid spraying system of FIG.  15 . 
     FIG. 19 is a fragmentary cross-sectional view of an air cap, the barrel and a fluid distribution block of the fluid spraying system of FIG. 15 taken along line  19 — 19  of FIG.  17 . 
     FIG. 20 is a cross-sectional view of the fluid spraying system of FIG. 15 taken along line  20 — 20  of FIG.  19 . 
     FIG. 21 is a schematic representation of a control system. 
     FIG. 22 is a schematic representation of a control system according to a particularly preferred embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 and 2, a fluid spraying system  10  is shown according to an exemplary embodiment of the present invention. According to a preferred embodiment, system  10  is intended to provide for improvement in the function of a spray gun for delivering a two-part water-based adhesive to an external surface (not shown). System  10  delivers four fluids: a primary fluid such as an adhesive, a secondary fluid such as an activator, a discharge fluid such as atomization air, and a discharge fluid such as fan air. Also provided is a pneumatic fluid such as cylinder air. System  10  includes four fluid circuits: an adhesive fluid circuit  12 , a fan air fluid circuit  14 , an atomization air fluid circuit  16 , and an activator fluid circuit  20 . Also provided is a cylinder air fluid circuit  18 (see FIG.  2 ). Each fluid circuit flows through a body or block (shown as a housing  120 ) providing an air cap assembly  64  and a nozzle assembly  86 . 
     The term “circuit” refers to any system of one or more passages, conduits, chambers, channels, or the like allowing or providing for the flow of one or more fluids. The term “flow” refers to the routing, direction, channeling, moving, circulation, etc. of a volume or quantity of a fluid a certain rate or pressure. The term “fluid” refers to any material that is capable of flowing, such as a liquid or a gas or combinations thereof. 
     The adhesive flows through an outlet  76  of air cap assembly  64  in a generally axial direction through a central cavity  140  of housing  120 . A piston assembly  22  and a needle assembly  40 , which are controlled by the cylinder air, turn on or off the discharge of the adhesive through outlet  76 . The atomization air, which “atomizes” (i.e., the breaking of a fluid (e.g., adhesive, activator, water, etc.) into small droplets or bubbles that are equally distributed in a fluid stream), flows in a generally axial direction to outlet  76  through an outlet  74  that circumscribes outlet  76 . Fan air flows in a generally axial direction through a vertical fan air conduit  136  leading to a set of radial ports  94  in a nozzle  88  positioned at a radial distance from radial ports  92 . The adhesive and the atomization air flow to air cap assembly  64  through radial ports  92 . The activator flows to air cap assembly  64  through a set of separate threaded needle tubes  192  within a fan air chamber  82  of air cap assembly  64 . (The activator is “atomized” by the fan air within a fan air passage  62  of an air cap  70 ; each of separate needle tubes  192  for the activator terminates within air cap  70  so that the atoniization occurs throughout the length of fan air passage  62  and not only as the activator is ejected from air cap  70 .) An atomized adhesive fluid stream  200  and an atomized activator fluid stream  206  are mixed at an impinging area  208  external to air cap  70  (see FIG.  11 ). 
     System  10  includes a number of removable parts and assemblies intended for simple construction, maintenance and servicing. A ring  58  of an end cap assembly  50  is threadedly connected to a protrusion  114  of housing  120 . Piston assembly  22  is configured for radial movement within end cap assembly  50 . A fluid connector block or manifold  100  (with associated plenium) is mounted to housing  120  by fasteners (shown as a threaded screw  298 ) fit through an aperture  296 . Plenum  100  is intended to provide a coupling point for an adhesive source  36 , a fan air source  38  and an atomization air source  44 . An activator block  170  and a secondary block  144  are mounted to housing  120  by fasteners (shown as threaded screws  294 ) fit through apertures  292 . Secondary block  144  is intended to provide a coupling point for a cylinder air source  56  and an activator source  46 , as well as a vertical mounting hole  112  for attaching housing  120  to a handle and/or trigger assembly (not shown). A retaining ring  68  of air cap assembly  64  is threadedly connected to a protruding ring  186  of housing  120 . Nozzle assembly  86  is disposed within air cap assembly  64  and is intended to provide a distribution point for distributing the adhesive, atomization air and fan air. 
     The clogging of fluid spraying system  10  (e.g., blockage of the fluid circuits, inlets, intakes, outlets, discharges, ports, etc. that may result in the fluid spraying system from operating efficiently) is intended to be reduced by the activator being turned on and off timed with the adhesive being turned on and off to correctly break any water from the adhesive and to provide the proper ratio of activator to adhesive. The activator is “atomized” by fan air within fan air passage  62  of an air horn (shown as a wing  72 ) of air cap  70  and the adhesive is “atomized” by the atomization air as it is discharged from air cap  70  through outlet  76  and outlet  74 . The fan air may also assist in breaking any water from the adhesive. Referring to FIG. 11, adhesive is atomized by the atomization air and the fan air (having activator fluid) such that a substantial portion of any water in the adhesive is driven off. The adhesive and the atomization air are discharged from air cap  70  through outlet  76  and outlet  74  to form resulting atomized adhesive fluid stream  200 , which is generally cone-shaped (see FIGS.  11 A- 11 B). The activator is “atomized” by the fan air in fan air passage  62  of wing  72  to form a resulting atomized activator fluid stream  206  (see FIG.  11 B). Atomized actuator fluid stream  206  is discharged from an output  78  at about a 60-degree angle relative to atomized adhesive fluid stream  200 . Atomized activator fluid stream  206  comes in contact with atomized adhesive fluid stream  200  at impinging area  208  external to air cap  70 , which may result in further atomization of the adhesive, to form a resulting activated adhesive fluid stream  210 . Atomized activator fluid stream  206  tends to narrow or flatten the cone shape of atomized adhesive fluid stream  200 . Activated adhesive fluid stream  210  consists of generally equally distributed activated adhesive droplets that form from the separation of the adhesive (which may be an adhesive and water emulsion) and water (which may be held together by a surfactant). Activated adhesive fluid stream  210  may subsequently be discharged on a substrate or surface to be covered (not shown) such as a mylar film, a paper, a work surface, an article of furniture, an architectural wall, a work environment accessory, etc. According to alternative embodiments, the atomized activator fluid stream may impinge upon the atomized fluid stream at any oblique angle relative to the needle. It is intended that fan air discharged from the air cap at a high pressure will tend to widen the “fan” shape of the atomized adhesive fluid stream. 
     It is intended that the clogging of fluid spraying system  10  (e.g., blockage of the fluid circuits, inlets, intakes, outlets, discharges, ports, etc.) and inconsistent ratios of adhesive to activator may be further inhibited by using a pressure adjustment mechanisms (shown as an activator flow control assembly  146  for the activator fluid circuit) to regulate or control the flow (i.e., volume and rate of the fluids through the respective fluid circuits) of each fluid circuit. According to a particularly preferred embodiment, each of the fluid circuits may be electronically controlled (i.e., turned on or off) for certain periods (e.g., the time the activator fluid stream meets the adhesive fluid stream at the impinging area) to provide for the desired rate, volume, pressure, quantity, etc. of fluid (e.g., the flow of the activator may be precisely metered to the corresponding flow of the adhesive). Such independent control by the pressure adjustment mechanisms is intended to provide for uniformity and consistency of the application of, for example, a two-part water-based adhesive. In particular, an activator delivery metering system (not shown) controlled at least in part by activator flow control assembly  146  may be configured to provide for “linearity” as adjustments are made over the range of adjustment of the flow of the activator fluid. “Linearity” is the even, controlled, uniform, etc. flow of a fluid through a fluid circuit. According to a particularly preferred embodiment, the activator flow control screw delivers a volume of activator fluid in linear increments of rotation of the flow control screw. According to alternative embodiments, the pressures of each fluid circuit may be regulated in relation to the other circuits (e.g., the flow pressure of the adhesive to the flow pressure of the activator may be set at a ratio of about 8:1 or 22:1). According to a particularly preferred embodiment, the ratio of the adhesive to the activator is determined by the molecular makeup of the adhesive. 
     Referring to FIG. 21, a schematic representation of a control system  522  for fluid spraying system  10  is shown according to a preferred embodiment. Control system  522  is intended to provide for the independent regulation of fluids through the fluid circuits. Control system  522  may include a controller  232  such as a programmable logic controller under the operation of a control program  516  (e.g., implemented in software). An input device  514  (e.g. a trigger, touch-pad, keyboard, keypad, sensors, etc.) for actuation of fluid spraying system  10  is coupled to controller  232 . Other instrumentation  518  (such as a display screen, gauges, monitors, touch-pad, user interface or other indicators of any type) as well as other input devices (not shown) may also be coupled to controller  232 . Control system  522  (and other elements of fluid spraying system  10 ) may be powered by a power source  512 . According to a particularly preferred embodiment, the power source is a 24 volt DC power supply. According to alternative embodiments, multiple power sources may be coupled to the controller (e.g., a separate power source for each fluid circuit). 
     As will be apparent to those of ordinary skill who review this disclosure, the control system and its controller may also have associated with it timing and/or control circuits activated by input devices, power sources, memory storage modules, display systems and/or instrumentation (e.g., regulators, sensors for monitoring temperature, volume, pressure or other variables, heating and/or cooling systems, etc.) and the like. According to a preferred embodiment, the control system implements the control program in a series of steps (which may according to alternative embodiments be implemented in a variety of other sequences and/or with a variety of other inputs, outputs, steps or instructions). According to alternative embodiments, the control system may be implemented in a stand-alone digital processor, or integrated with a microprocessor of the like used to monitor and/or control other fluid spraying systems and functions. The control system is not intended to be limited to any particular type of controller capable of implementing the intended functionality (i.e., regulating the flow of the fluids through the fluid circuits). 
     The control system, according to a preferred embodiment, may include a programmable logic controller (such as a PLC that performs “ladder logic” operations for implementing a control program and which provides output signals based on input signals provided by an operator or otherwise acquired). According to a particularly preferred embodiment, the controller is a Micrologic 1000 PLC Model #1761-L32 BWA commercially available from Rockwell Automation Allen-Bradley Corporation of Milwaukee, Wis. According to alternative embodiments, other suitable controllers of any type may be included in the control system. For example, controllers of a type that may include a microprocessor, microcomputer or programmable digital processor, with associated software, operating systems and/or any other associated programs to collectively implement the control program may be employed. According to alternative embodiments, the controller and its associated control program may be implemented in hardware, software or a combination thereof, or in a central program implemented in any of a variety of forms. According to a particularly preferred embodiment, input to the control program is provided by turning a trigger “on” and the control program performs operations (i.e., turning valves “on” and “off” in certain sequences or for certain periods) while the trigger is “on” and for a period after the trigger is turned “off”. 
     Referring to FIG. 10, a schematic diagram of the electronic circuitry regulated by control system  522  is shown according to a preferred embodiment. The turning on and off of each fluid through each fluid circuit is individually regulated by control system  522 . Control system  522  turns valve  226  “on” and “off” in response to input or output from controller  232 . When valve  226  is turned “on”, compressed air exerts a pressure on the activator fluid in activator source  46  (e.g., acting as a “pressure pot”) to cause the activator fluid to flow through activator fluid circuit  20  under pressure. (The volume and rate of the activator in the fluid spraying system is further regulated by activator flow control assembly  146 .) In a similar manner, compressed air in fluid communication with adhesive source  36  forces the adhesive fluid through adhesive fluid circuit  12  (e.g., acting as a “pressure pot”). A control element (shown as a solenoid valve  224 ) turned “on” and “off” by controller  232  regulates the flow of the adhesive through adhesive fluid circuit  12 . A control element shown as a solenoid valve  220  is turned “on” and “off” by controller  232  to turn on and off the atomization air through atomization air fluid circuit  16 ; a control element shown as a solenoid valve  222  is turned “on” and “off” by controller  232  to turn on and off the fan air through fan air fluid circuit  14 ; and a control element shown as a solenoid valve  228  turned “on” and “off” by controller  232  to turn on and off the cylinder air through cylinder air fluid circuit  18 . According to a preferred embodiment, individual check valves, which may have display gauges, monitors, user interfaces, etc., may be manipulated to regulate the pressure of the compressed air in the adhesive fluid circuit, the atomization air fluid circuit, the activator fluid circuit, the fan air fluid circuit and the cylinder air fluid circuit. According to an alternative embodiment as shown in FIG. 10, a control element shown as a solenoid valve  226  may regulate the flow of the activator through activator fluid circuit  20 . 
     Referring to FIG. 22, a schematic representation of control system  522  for fluid spraying system  10  is shown according to a particularly preferred embodiment. Control system  522  includes controller  232  powered by power supply  512 . A switch control  532  selects certain modules or test programs (e.g., purge test, viscosity test, system off, etc.) to be run when a trigger  530  is turned on. Inputs  534  are processed by a control program of controller  232 , which provides outputs  536 . Outputs  536  turn an activator solenoid  538  on or off. Likewise, outputs  536  turn a cylinder air solenoid  540 , a fan air solenoid  542 , and an atomization air solenoid  544  on or off. When a solenoid is turned on, fluid may flow through a fluid circuit, and when a solenoid is turned off, fluid is inhibited from flowing through a fluid circuit. For example, when cylinder air solenoid  540  is turned on, piston  34  and needle  42  are retracted so that adhesive may flow through adhesive fluid circuit  12  and be discharged through outlet  76 . 
     Referring further to FIG. 22, pressure control mechanisms (shown as pressure regulators  546 ,  548 ,  550  and  552 ) regulate the air pressure through each fluid circuit. For example, pressurized air from an air supply is controlled by regulator  552  so that air pressure is applied on activator fluid in an activator fluid source (shown as a pressure pot  554 ). Activator flows from pressure pot  554  to activator flow control assembly  146 , which linear selected volumes of activator fluid in activator fluid circuit  20 . Likewise, pressurized air from an air supply is regulated by pressure regulator  550  so that a pressure is applied to adhesive fluid in an adhesive fluid source (shown as a pressure pot  556 ). Adhesive flows from pressure pot  556  to nozzle assembly  86  and is discharged through outlet  76 . 
     The clogging of fluid spraying system  10  (e.g., blockage of the fluid circuits, inlets, intakes, outlets, discharges, ports, etc.) is intended to be reduced by turning the fluid circuits “on” and “off” in a particular sequence, order, cycle, etc. Referring to FIG. 14, a flow chart detailing the sequence in which the fluid circuits are turned “on” and “off” is shown according to a preferred embodiment of the present invention. The turning “on” of an input device or trigger (step  240 ) turns on operation of control system  522 . Upon turning “on” the trigger, valve  222  and valve  220  are opened so that fan air and atomization air flow through the respective fluid circuits (step  242  and step  246 ). Turning the fan air “on” (step  242 ) and turning the atomization air “on” (step  246 ) purges any debris or excess fluids from fan air fluid circuit  14 , atomization air fluid circuit  16  and discharge  96  for a pre-selected period selectable by a timer  248 . Turning the fan air “on” and turning the atomization air “on” before turning the adhesive “on” and the activator “on” is intended to provide for a balanced, linear air flow through the respective fluid circuits. Also, turning the fan air “on” and turning the atomization air “on” before turning the adhesive “on” and the activator “on” is intended to provide a path for the atomization air and the fan air toward the substrate or surface. Such path is intended to provide a direct route for the activated adhesive fluid stream from the nozzle to the substrate, such that any water in the adhesive may be deflected towards the periphery of the path, which according to an alternative embodiment, may be collected in a filter mechanism (not shown) such as a vacuum. 
     Upon completion of the purge, as measured by a timer (step  248 ), valve  226  is opened so that the activator fluid flows through activator fluid circuit  20  (step  250 ) and valve  228  is opened so that the cylinder air flows through cylinder air fluid circuit  18  to turn on the flow of the adhesive through adhesive fluid circuit  12  (step  254 ). Turning the activator fluid “on” (step  250 ) and turning the adhesive “on” (step  254 ) occurs generally simultaneously such that the adhesive and the activator both reach impinging area  208  at about the same time (step  256 ) such that a fluid stream is discharged external to air cap  70  (i.e., system  10  discharges an atomized “spray” which is a combination of adhesive, atomization air, activator, fan air and atomized combinations thereof). 
     Activated adhesive fluid stream  210  is discharged on the substrate until the trigger is turned “off” (step  258 ). Turning the trigger “off” (step  258 ) causes the flow of the activator to subsist (step  260 ) and the cylinder air to subsist, which in turn turns “off” the flow of the adhesive (step  264 ). Turning the activator fluid “off” (step  260 ) and turning the adhesive “off” (step  264 ) occur generally simultaneously. Subsequently, fan air and atomization air continue to purge fan air fluid circuit  14 , atomization air fluid circuit  16  and discharge  96  for a period controlled by a timer  266 . The fan air is then turned “off” (step  268 ) and the atomization air is then turned “off” (step  270 ) so that no fluid is discharged or sprayed from air cap  70  (step  272 ). 
     Referring to FIG. 4, piston assembly  22  is shown disposed within a chamber  32  of end cap assembly  50 . Piston assembly  22  includes a generally circular-shaped piston  24  having a top surface  26  and a bottom surface  28 . A generally cylindrical protrusion  30  for guiding a needle  42  of needle assembly  40  extends from top surface  26  of piston  24 . Piston assembly  22  also includes a piston spring  60  disposed between an end cap  52  of end cap assembly  50  and bottom surface  28  of piston  24 . 
     In operation of piston assembly  22 , a full supply line pressure of cylinder air is forced against top surface  26  of piston  24  causing the compression of piston spring  60  and the retraction of needle  42  toward an adjustment screw  54  (see FIG.  4 ). When the pressure of the cylinder air subsides, piston spring  60  decompresses to return piston  24  toward air cap  70 . When piston  24  is retracted toward adjustment screw  54 , needle  42  is likewise retracted toward adjustment screw  54  and a needle spring  48  is compressed. When needle spring  48  is decompressed, needle  42  is returned toward air cap  70 . According to a particularly preferred embodiment, the end cap assembly includes a three way valve to discharge air from the end cap assembly to the atmosphere so that the piston may retract when the cylinder air is turned off. 
     It is intended that the clogging of fluid spraying system  10  (e.g., blockage of the fluid circuits, inlets, intakes, outlets, discharges, ports, etc.) be further reduced by a fast-acting needle valve. According to a particularly preferred embodiment, the flow of the adhesive through outlet  76  is turned on and off by needle  42 , which coacts with outlet  76  to operate as a fast-acting valve, and is intended to provide a rapid transition (i.e., using an electronic control) from an opened position to a closed position (see FIG.  3 ). When the cylinder air is turned on, needle  42  retracts towards adjustment screw  54  and the adhesive is discharged through outlet  76  of air cap  70 ; when the cylinder air is turned off, needle  42  is returned toward air cap  70  such that the flow of the adhesive is inhibited from being discharged from outlet  76 . According to an alternative embodiment as shown in FIG. 4, the distance that adjustment screw  54  is extended or retracted within end cap  52  may be varied to compress or decompress needle spring  48  and adjust the rate needle  42  extends and retracts relative to end cap  52 . As a result, the rate at which needle  42  is axially extended and retracted (i.e., moved from the opened position to the closed position) within outlet  76  may be varied. According to a particularly preferred embodiment, the needle is either fully retracted or fully extended, which is intended to provide effective metering of the amount of adhesive that is discharged from the fluid spraying system. Piston assembly  22  and needle assembly  40  include seals to inhibit air and adhesive from leaking into chamber  32 . An annular seal (shown as an O-ring  288 ) is disposed around piston  24  to inhibit the cylinder air from entering a spring chamber  34  and an O-ring  290 ) is disposed around protrusion  30  of piston  24  to inhibit the adhesive in central cavity  140  from entering chamber  32 . 
     Referring to FIG. 4, the flow of each fluid circuit for each fluid (i.e., adhesive, atomization air, activator, fan air and cylinder air) is shown. The adhesive from the adhesive source flows through a tube  276  to an adhesive intake  102  of plenum  100 . The adhesive then flows into a transverse adhesive conduit  122 , which is in fluid flow communication with central cavity  140 . As needle  42  is retracted toward adjustment screw  54 , the adhesive is permitted to be discharged from air cap assembly  64  through outlet  76 . 
     Atomization air from the atomization air source flows through tube  276  to an atomization air intake  106  of plenum  100 . The atomization air then flows into a transverse atomization air conduit  126 , which is in fluid flow communication with a vertical atomization air conduit  138  generally co-axial with needle  42 . The atomization air then flows through a central orifice  116  of nozzle  88  to an atomization air chamber  84  of air cap  70 . The atomization air is then discharged from air cap  70  through outlet  74 . 
     Referring further to FIG. 4, fan air from the fan air source flows through tube  276  to fan air intake  104  of plenum  100 . The fan air then flows into a transverse fan air conduit  124 , which is in fluid flow communication with vertical fan air conduit  136  generally co-axial with needle  42 . The fan air then flows through radial ports  94  of a distribution ring  90  of nozzle  88  to fan air chamber  82  of air cap  70 . The fan air then flows through fan air passage  62  of air cap  70  and discharged from wing  72  through an outlet  78 . 
     The activator from the activator source flows through tube  276  to activator intake  110  of secondary block  144 . The activator then flows into a transverse activator channel  142  to an activator cavity  134 . As a screw  148  is retracted from secondary block  144 , the activator flows from activator cavity  134  to an activator channel  172 . The activator then flows through an inlet  178  of a solenoid  176 . A gate  180  regulates the passage of the activator from inlet  178  to an outlet  182  of solenoid  176 . From outlet  182 , the activator then flows to a Y-shaped diverter  188 , and then to an activator tube  190  and through needle tubes  192 . The fan air within fan air passage  62  atomizes the activator and the resulting atomized activator fluid stream  206  is discharged from air cap  70  through outlet  78 . 
     Cylinder air from the cylinder air source flows through tube  276  to cylinder air intake  108  of secondary block  144 . The cylinder air then flows into a transverse cylinder air conduit  130 , which is in fluid flow communication with a vertical cylinder air conduit  132  generally co-axial with needle  42 . When the cylinder air is turned on, a blast of cylinder air is forced against top surface  26  of piston  24  to cause needle assembly  40  to extend and retract relative to adjustment screw  54 ; when the cylinder air is turned off, needle assembly  40  returns or extends relative to adjustment screw  54 . The turning on and off of the cylinder air occurs at a rapid rate of speed, causing needle assembly  40  to extend and retract at a rapid rate of speed. Such rapid extension and retraction of needle assembly  40  is intended to assist in reducing the discharge of adhesive from outlet  76 . 
     Housing  120  is intended to provide a mounting point for attaching components of system  10  such as plenum  100 , activator block  170  and secondary block  144  (see FIG.  12 ). Central cavity  140  of housing  120  includes a storage area for the adhesive. A generally frusto-conical shaped cartridge  98  is disposed within central cavity  140 . Threaded screws  298  are fit through apertures  296  and spacers  286  (e.g., washers, seals, O-rings, etc.) to mount activator block  170 , secondary block  144  and plenum  100  to housing  120 . Protruding ring  186  of housing  120  is threadedly connected to retaining ring  68 . Protruding ring  186  includes radial ports  214  for the flow of fan air through fan air fluid circuit  14 , and radial ports  212  for the flow of the atomization air through atomization air fluid circuit  16 . Ports  212  and  214  are generally evenly spaced from each other and about the internal periphery of protruding ring  186 . (Ports  214  are spaced a greater distance from the center of protruding ring  186  than are ports  212 .) A lower portion of nozzle assembly  86  fits within protruding ring  186 , and distribution ring  90  abuts against protruding ring  186 . Distribution ring  90  includes radial ports  92  for the flow of the atomization air through atomization air fluid circuit  16 , and radial ports  94  for the flow of the fan air through the fan air fluid circuit  14 . Radial ports  92  and  94  are generally evenly spaced from each other. Housing  120  also includes passages for the flow of the fluids through the fluid circuits of fluid spraying system  10 . 
     Plenum  100  includes intakes for receiving fluids (e.g., adhesive, atomization air, activator, fan air, cylinder air, etc.) from the sources external to housing  120 . Adhesive intake  102 , fan air intake  104  and atomization air intake  106  of plenum  100  are connected to each respective source by a hollow elongate flexible member (shown as tubes  276 ). Intakes  102 ,  104  and  106  are in fluid flow communication with fluid circuits  12 ,  14  and  16 , respectively. Intakes  102  and  104  are generally perpendicular to needle  42 , transverse adhesive conduit  122 , transverse fan air conduit  124  and transverse atomization air conduit  126 . Intake  106  is generally coaxial with needle  42 . Plenum  100  may also include apertures  252 , which may be threaded, for fasteners or set screws (not shown) for mounting plenum  100  to the handle and/or trigger assembly. 
     Secondary block  144  is mounted to housing  120  and to activator block  170  by fasteners (shown as threaded screws  284 ) fit trough apertures  282 . Secondary block  144  includes intakes for receiving the fluids from the sources external to housing  120 . A hollow elongate flexible member (shown as tubes  276 ) connects activator intake  110  and cylinder air intake  108  of secondary block  144  to each respective source. Intakes  108  and  110  are in fluid flow communication with fluid circuits  18  and  20 , respectively. Intakes  108  and  110  are generally coaxial with needle  42 . Guide holes  218 , which may assist in manufacturing for drilling, boring, or molding conduits, channels or passage, may be included in activator block  170  and secondary block  144  and filled with spacers or plugs  216 . According to any alternative or preferred embodiment, any fastener may connect the hollow elongate flexible members to the secondary block and/or the plenum (e.g., capture clamp, bayonet twistlock fastener, spring clips, etc.). 
     Activator flow control assembly  146  is mounted to secondary block  144  (see FIGS. 6-7 and  12 ). Activator flow control assembly  146  variably adjusts the amount of activator that is mixed with the fan air in fan air passage  62 . Activator flow control assembly  146  includes screw  148  having a threaded end  156  disposed within and surrounded by a jamb nut  150 , a medial portion  158  disposed within a spacer  152  and a terminal end  160  surrounded by a flexible, a radial seal  154 . Terminal end  160  of screw  148  includes a groove having a leading edge  128 . In operation of activator flow control assembly  146 , screw  148  is retracted from secondary block  144  to expose a greater portion of leading edge  128  to seal  154  such that a volume of the activator may flow from activator cavity  134  to activator channel  172 . As screw  148  is extended into secondary block  144 , a lesser portion of leading edge  128  is exposed to seal  154  such that leading edge  128  abuts against seal  154  to inhibit the flow of the activator from activator cavity  134  to activator channel  172 . According to any alternative or preferred embodiment as shown in the FIGURES, seals (shown as O-rings  234 ) may be disposed between secondary block  144  and activator block  170  to inhibit the activator from leaking from activator channel  172 , and may be disposed between screw  148  and seal  154 . 
     Activator block  170  is mounted to secondary block  144  by a fastener (shown as threaded screws  284 ) fit through apertures  282 . Activator block  170  is intended to provide for the flow of the activator to air cap assembly  64 . Solenoid  176  is disposed between activator block  170  and secondary block  144 . Electrical connectors (shown as wires  230 ) are connected to an electrical circuit (not shown) to independently regulate the amount of activator that flows to air cap assembly  64 . Referring to FIGS. 5 and 8, activator block  170  includes inlet  178 , seal  154  and solenoid  176 . Solenoid  176  includes inlet  178  and outlet  182  separated by gate  180 . Gate  180  acts as a valve and permits the activator to flow from inlet  178  to outlet  182 . Gate  180  may include a diaphragm that is extended and retracted relative to a coil in response to a signal. (According to an alternative embodiment as shown in FIG. 8, a plug may be disposed within inlet  178  and outlet  182  to prevent the activator from leaking from activator fluid flow of circuit  20 .) After being discharged from outlet  182 , the activator flows through diverter  188 . The activator flows from Y-shaped diverter  188  to threaded needle tubes  192  disposed at least partially within fan air passage  62  of wing  72 . 
     Nozzle assembly  86  assists in the distribution of the adhesive, atomization air and fan air to air cap assembly  64  (see FIG.  3 ). Cartridge  98  of nozzle assembly  86  cooperates with protrusion  30  of piston  24  to further guide needle  42  through central cavity  140 . Cartridge  98  includes radial seals (shown as O-rings  280 ) to inhibit the adhesive from flowing into spring chamber  34 . Radial ports  92  of nozzle  88  distribute atomization air from ports  212  of protruding ring  186  to air cap assembly  64 , and radial ports  94  of nozzle  88  distribute fan air from ports  214  of protruding ring  186  to air cap assembly  64 . A fluid tip  80  having central orifice  116  extends from distribution ring  90 . A terminal end  274  of needle  42  is configured to selectively block central orifice  116  of fluid tip  80 . In operation of needle assembly  40 , when needle  42  is retracted towards adjustment screw  54  the adhesive is permitted to flow through central orifice  116  of fluid tip  80 . When needle  42  is extended toward air cap assembly  64 , terminal end  274  of needle  42  blocks central orifice  116  such that the adhesive is inhibited from escaping through central orifice  116 . 
     Air cap  70  is adapted to house nozzle  88 . Retaining ring  68 , which may be threaded, secures air cap  70  to protruding ring  186  of housing  120 . According to an alternative embodiment as shown in FIG. 9, air cap assembly  64  may include needle tubes  192  in fluid communication with activator tube  190  to provide for the flow of the activator from activator block  170  to fan air chamber  82 . Air cap assembly  64  also includes atomization air chamber  84 . Atomization air that flows through central orifice  116  of fluid tip  80  then flows to atomization air chamber  84  and further flows through outlet  74  of air cap  70 . The adhesive from central cavity  140  is discharged from air cap through outlet  76 . According to any alternative or preferred embodiments as shown in the FIGURES, a seal (shown as an O-ring  278 ) may be disposed between nozzle  88  and retaining ring  68  to prevent atomization air and fan air from leaking out air cap assembly  64 . 
     A fluid spraying system  310 , an alternative embodiment of fluid spraying system  10 , is shown in FIGS. 15-20. Referring to FIG. 15, system  310  includes a fluid distribution block or manifold (shown as a plenum  400 ) mounted to a housing  320  by fasteners (shown is threaded screws  498 ) fit through apertures  496 . An internal body (shown as a barrel  344 ) is disposed within and extends through housing  320 . An end cap assembly  336  is threadedly mounted to an intake end  346  of barrel  344 , and an air cap assembly  364  (at least partially surrounding a nozzle assembly  386 ) is threadedly connected to a discharge end  348  of barrel  344 . System  310  is intended to provide for the routing or flow of adhesive, atomization air, activator, fan air and cylinder air through an adhesive fluid circuit  312 , an atomization air fluid circuit  316 , an activator fluid circuit  308 , a fan air fluid circuit  314  and a cylinder air fluid circuit  318 , respectively. The fluid circuits of system  310  are similar to the fluid circuits of system  10 . For example, the fluid circuits of system  310  are generally co-axial and include few harsh angles, which improves fluid flow by decreasing resistance and friction against the walls of each fluid circuit. Also, the simple construction of system  310  is intended to reduce its total weight by using space more efficiently. Such simple construction is intended to provide for rapid maintenance, servicing, repair, etc. and reduce the likelihood of potential leaks in the fluid circuits. 
     End cap assembly  336  of system  310  includes an end cap  352  defining and an end cap chamber  332 . An adjustment screw  354  is threadedly connected to end cap  352  to variably compress and decompress a piston spring  360  and a needle spring  504 . A piston assembly  322  is disposed within end cap chamber  332 . Piston assembly  322  includes a piston  324  having a top surface  326  and a bottom surface  328 . A protruding member  330  extends from top surface  326  of piston  324  and provides support to a needle  342  of a needle assembly  340 . In operation of piston assembly  322  and needle assembly  340 , the cylinder air is forced against top surface  326  of piston  324 , which causes piston  324  to compress piston spring  360 . As result, needle  342  is retracted towards adjustment screw  354  so that adhesive may flow through a central orifice  440  of housing  320  (and externally relative to air cap assembly  364 ) through an outlet  376 . When piston returns or is extended toward air cap assembly  364 , needle  342  blocks outlet  376  such that the adhesive is inhibited from being discharged from outlet  376 . Piston spring  360  and needle spring  504  allow needle assembly  340  to extend and retract at a rapid rate of speed, which in turn allows the adhesive to variably be sprayed out of outlet  376  and is intended to reduce clogging. According to any preferred or alternative embodiment shown in the FIGURES, seals (shown as O-rings  502 ) may be disposed around piston assembly  322  and needle assembly  340  to inhibit the cylinder air and the adhesive from leaking into a piston spring chamber  334  of end cap chamber  332 . 
     A cylinder nut  420  is threadedly mounted to end cap  352 . Cylinder nut  420  includes a radial flange  422  having orifices  442  for cylinder air. A circular-shaped protruding member  416 , which may be threaded, extends from flange  422 . Protruding member  416  fits within an aperture  434  of a cylinder washer  430 . (The diameter of aperture  434  is greater than be diameter of protruding member  416 .) Cylinder washer  430  includes orifices  432  for the cylinder air. A seal (shown as an O-ring  506 ) may be disposed between cylinder washer  430  and housing  320 . 
     Plenum  400  is mounted to housing  320  by a fastener (shown as a threaded screw  494 ) fit through an aperture  484 . Plenum  400  includes an activator intake  410 , a fan air intake  404 , an atomization air intake  406 , a cylinder air intake  408  and an adhesive intake  402  for connecting each respective source (not shown) by tubes  456 . Intakes  404 ,  406 ,  408  and  410  are generally co-axial with each other (adhesive intake  402  is shown disposed generally transverse to intakes  404 ,  406 ,  408  and  410 ). The mounting of tubes  456  to plenum  400  is intended to provide for monitoring or metering of the flow pressure of the fluids through each respective fluid circuit. A mounting hole  412  drilled, bored, molded, etc. in plenum  400  is intended to provide a mounting point for attaching a handle and/or trigger assembly (not shown) to system  310 . Housing  320  also includes a flow control assembly  446  similar to activator flow control assembly  146 , to regulate the amount of activator that is discharged through activator fluid circuit  308 . A circular recess  338  of housing  320  is configured to receive barrel  344 . 
     An activator block  470  is connected to housing  320  by threaded screws  498  fit through apertures  496 . Activator block  470  is generally square-shaped and includes a generally square-shaped aperture  428 . In operation of fluid spraying system  310 , flow control assembly  446  includes a screw  448  that regulates the amount of the activator that flows through an activator channel  472  to an inlet  478  of a solenoid  476 . A gate  482  disposed between inlet  478  and an outlet  480  of solenoid  476  regulates the quantity of activator that passes from inlet  478  to outlet  480 . After passing through outlet  480  of solenoid  476 , activator then flows through an activator passage  486  to a diverter  488  disposed in housing  320 . Diverter  488  is intended to provide for the flow of activator to an activator port  490 . Needle tubes  492  are threadedly connected to activator port  490  and disposed at least partially within a fan air chamber  382  of air cap assembly  364 . According to an alternative embodiment as shown in FIG. 16, a seal (shown as O-ring  438 ) may be disposed between activator block  470  and housing  320 . 
     Barrel  344  includes a generally square-shaped bridge  350  that is configured to fit within aperture  428  of activator block  470  (see FIG.  18 ). Bridge  350  includes a port  418  for receiving the activator from port  490 . Bridge  350  also includes radial orifices  366  for fan air such that fan air may flow through orifices  432  to orifices  366 . A cylinder  356  having a perimeter less than the perimeter of bridge  350  includes radial orifices  358  for atomization air, such that atomization air may pass from orifices  442  to orifices  358 . Cylinder  356  is shaped so that it may fit within circular recess  338  of housing  320 . A threaded ring  374  of barrel  344  fits through aperture  434  of cylinder washer  430  and is threadedly connected to protruding member  416  such that barrel  344 , activator block  470 , housing  320 , cylinder washer  430  and cylinder nut  420  may be secured together in the axial direction as a single unit. Discharge end  348  of barrel  344  includes radial orifices  396  for atomization air and orifices  366  for fan air. 
     A rear portion of nozzle assembly  386  is at least partially fit through a circular recess  388  of barrel  344 , and a front portion of nozzle assembly  386  is disposed at least partially within air cap assembly  364 . A distribution ring  390  of nozzle assembly  386  includes interior orifices  392  for atomization air and exterior orifices  394  for the fan air. A fluid tip  380  extends from distribution ring  390 . A retaining ring  368  of air cap assembly  364  is threadedly connected to discharge end  348  of barrel  344 . Air cap assembly  364  includes an air cap  370  having wings  372 . Fan air chamber  382  is disposed in wings  372 . 
     Referring to FIGS. 17 and 19, the flow of each fluid circuit for each fluid (e.g., adhesive, the atomization air, activator, fan air and cylinder air) is shown. Adhesive flows from adhesive intake  402  of plenum  400  to central orifice  440  of housing  320 . As needle  342  is retracted towards adjustment screw  354  adhesive is permitted to flow through fluid tip  380  and through outlet  376  of air cap  370 . Atomization air flows from intake  406  of plenum  400  to a transverse atomization air conduit  426 . From transverse atomization air conduit  426 , the atomization air then flows through orifices  392  of distribution ring  390  and into an atomization air chamber  384  of air cap  370 . The atomization air is then discharged externally from air cap  370  through outlet  376 . The fan air flows from intake  404  of plenum  400  to a transverse fan air conduit  424 . The fan air then travels through a horizontal fan air conduit  436  to a fan air passage  362  of air cap  370 . The fan air then travels through air cap  370  and then through a discharge  378  of wings  372 . Referring to FIG. 20, activator flows from activator intake  410  of plenum  400  to activator channel  472 . The activator that passes through activator channel  472  then flows to solenoid  476 , which regulates the amount of activator that flows through diverter  488  to needle tubes  492 . Activator travels through needle tubes  492  to fan air chamber  382  and is discharged from air cap  370  through discharge  378  of wings  372 . The atomization and spraying pattern of atomization air, adhesive, activator, and fan air are similar to that described above with respect to FIGS.  9  and  11 - 11 B. 
     According to any alternative or preferred embodiments, a variety of adhesives may be used with the fluid spraying system. For example, a water-based adhesive wherein the atomization air and the fan air assist in breaking or separating the water from the adhesive may be employed, which may have environmental advantages over solvent-based adhesives. Other adhesives may include latex, neoprene, or acrylics. The adhesive may have a pH in the range from about 10-11 and in a wide range of viscosities. Water-in-oil emulsion adhesives having a tubular-shaped or cylindrical-shaped surfactant (i.e., resin) connecting the adhesive to water are particularly preferred, although hydroxyl group surfactants that separate the adhesive from water may also be used according to alternative embodiments. According to any alternative or preferred embodiments, the activator is acidic and may have a pH in the range of about 1-5, more preferably from about a pH of 1-3. For example, citric acid having a pH of about 1.5, zinc sulfide having a pH of about 3, or lactic acid having an acidic pH are all suitable activators. Also, the activator may be replaced by a cross-linking agent such as those cross-linking agents compatible with acrylics. The flow of the atomization air and the fan air through the respective fluid circuits may have a pressure from about 3-10 lbs./sq. inch to about 40 lbs./sq. inch (preferably from about 10-20 lbs./sq. inch.). According to a particularly preferred embodiment, the volume of the adhesive to the volume of the activator is at a ratio of about 15-25:1, more preferably at a ratio of about 18-22:1. According to a particularly preferred embodiment, the volume of activator fluid is varied until the resulting activated atomized adhesive fluid stream has a pH of about 6.8-7.0. 
     According to a particularly preferred embodiment, the flow of the adhesive through the adhesive fluid circuit is at a pressure of about 15 lbs./sq. in. The nozzle of the fluid spraying system is preferably spaced from the substrate at a distance of about 6-24 inches and is discharged from the nozzle at a rate of about 150 feet/minute. The pressure of the fan air is preferably about two times as great as the pressure of the atomization air when separating the water from the adhesive in an adhesive and water emulsion. The air cap assembly, the nozzle, the piston, the air cap, the housing and the needle assembly are commercially available from Kremlin Company of Stains, France. The solenoid and is commercially available from Lee Company of Westbrook, Conn. Preferably, the housing, the fluid distribution block, the activator block and the secondary block are constructed of Delrin® plastic, but may be constructed of metal according to alternative embodiments. The fasteners for connecting the plenum to the housing are preferably flat-headed machine screws, which are about 3 inches long and exposed about {fraction (7/16)} of an inch above the aperture. The O-rings are preferably constructed of Viton® rubber or Teflon® polymers and are generally impervious to acids and solvents. The piston assembly is preferably pneumatically controlled. The fan air outlet and the atomization air outlets are preferably of about equal sizes. Not wishing to be limited by theory, it is believed that the size of the outlet assists in about uniformly breaking the water apart from the adhesive in a water-based adhesive. The fan air outlet preferably has a diameter of about ⅛ inch, the atomization air outlet has a diameter of about ⅛ inch and the adhesive outlet has a diameter of about {fraction (60/1000)} inch. 
     It is important to note that the construction and arrangement of the elements of the fluid spraying system in the exemplary embodiments is illustrative only. Many variations are possible. According to alternative embodiments, any variety of fluids may be delivered, such as paints, adhesives, laminates, aerosols, coatings, insecticides, etc. The activator may be any type of product or catalyst that speeds up or completes a chemical reaction. According to other alternative embodiments, the fluid spraying system may include a wound polymer medium to remove particulate and water from the atomization air and the fan air. According to an alternative embodiment, the system may be employed as a one-part adhesive without the use of an activator, an activator block and/or a secondary block. The components of the fluid spraying system (e.g., housing, barrel, secondary block, fluid distribution block, etc.) may be constructed of plastic. The piston assembly may be controlled by any fast-acting mechanism such as a crank, a solenoid, a stepper, etc. According to an alternative embodiment, the fan air may flow from the fan air intake and through the orifice of the cylinder washer before entering the fan air passage. According to alternative embodiments, a variety of valves or fluid regulating devices or elements may be used such as check valves, ball valves, spigot controlled valves, solenoid valves, needle valves, pivot valves, etc. to regulate the flow of fluids through the fluid circuits. According to other exemplary embodiments, the fluid spraying system can be incorporated to be configured to be used with other conventional elements of a spray gun, or assembled from conventional or commercially available elements or assemblies of such conventional spray guns. According to an alternative embodiment, a fibrous filter media may be disposed around the nozzle to remove excess surfactant and water as it is discharged from the nozzle. 
     It is important to note that the terms “passage” is not meant as terms of limitation, insofar as the structures described in this specification (or alternative and/or equivalent structures) may serve to provide for the flow of a fluid through a channel, chamber, tube, conduit, inlet, intake, outlet, discharge, port, etc. 
     Although only a few exemplary embodiments of the present invention have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible in the exemplary embodiments (such as variations in sizes, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, or use of materials) without materially departing from the novel teachings and advantages of the invention. Accordingly, all such modifications are intended to be included within the scope of the invention as defined in the appended claims. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred embodiments without departing from the spirit of the invention as expressed in the appended claims. The order or sequence of steps, for example, of turning the fluid circuits “on” and “off” or turning the valves “on” or “off” may be varied or re-sequenced according to alternative embodiments of the invention. For example, the fan air may be turned “on” or “off” slightly before or after the atomization air is turned “on” or “off,” and the activator may be turned “on” or “off” slightly before the adhesive is turned “on” or “off.” In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures.