US3807641A

US3807641A - Spray head

Info

Publication number: US3807641A
Application number: US00323890A
Authority: US
Inventors: J Albright
Original assignee: Advance Products Corp
Current assignee: Advance Products Corp
Priority date: 1973-01-15
Filing date: 1973-01-15
Publication date: 1974-04-30
Anticipated expiration: 1991-04-30
Also published as: JPS49109218A; FR2213811B3; GB1424161A; DE2400745A1; JPS5722622B2; FR2213811A1; IT1008666B; CA990763A

Abstract

A spray head comprises a body having air and liquid inlet passageways terminating adjacent to each other within the body. A single resilient diaphragm is disposed across the ends of the two passageways and sealed against a seat at the end of the liquid inlet passageway. The diaphragm is held against the seat by a spring biased piston, and the diaphragm is raised from the seat by air pressure in the air inlet line. The air and liquid are mixed in a mixing cavity immediately under the diaphragm, and the mixture is discharged through an outlet passageway to a spray nozzle. The spray nozzle may be a ball-shaped member formed with a variety of openings to provide various discharge patterns.

Description

[451 Apr. 30, 1974 SPRAY HEAD James L. Albright, Benton Harbor, Mich.

[73] Assignee: Advance Products Corporation,

Benton Harbor, Mich.

221 Filed: Jan. 15, 1973 211 App]. No.: 323,890

[75] Inventor:

[52] US. Cl 239/412, 239/414, 239/417.5 [51] Int. Cl B05!) 7/00 [58] Field of Search 239/407, 412, 414, 416.4, 239/4175 [56] References Cited UNITED STATES PATENTS 2,596,687 5/1952 Hill 239/412 3,433,416 3/1969 Bauer et a1. 239/284 3,064,862 11/1962 Sanders 239/4ll X 2,515,865 7/1950 Fisher 239/412 X Primary ExaminerM. Henson Wood, Jr.

Assistant ExaminerJohn J. Love Attorney, Agent, or Firm-Olson, Trexler, Wolters, Bushnell & Fosse, Ltd.

[5 7] ABSTRACT A spray head comprises a body having air and liquid inlet passageways terminating adjacent to each other within the body. A single resilient diaphragm is disposed across the ends of the two passageways and sealed against a seat at the end of the liquid inlet passageway. The diaphragm is held against the seat by a spring biased piston, and the diaphragm is raised from the seat by air pressure in the air inlet line. The air and liquid are mixed in a mixing cavity immediately under the diaphragm, and the mixture is discharged through an outlet passageway to a spray nozzle. The spray nozzle may be a ba11-shaped member formed with a variety of openings to provide various discharge patterns.

10 Claims, 10 Drawing Figures PATENTED man an SHEU 1 0F 2 SPRAY HEAD BACKGROUND OF THE INVENTION This invention relates to improvements in spray heads.

The type of spray heads with which the present invention is concerned is that used for spraying lubricants or mold release agents into the cavities of casting dies. Spray heads of this type typically contain a body with airand liquid-inlet lines, and suitable valving within the body to control the air, wherebythe air pressure is used to deliver the liquid to a spray nozzle. The mixing of the air and liquid generally takes place in a discharge nozzle so that an atomized spray is discharged for impingement upon the surface to be lubricated. The aforesaid valving frequently consists of a ball check valve, needle valve or the like, all of which may be subject to deterioration and/or clogging during use. Furthermore, the spray nozzles themselves are often designed for only a fixed or predetermined spray pattern, which may not be satisfactory for all uses. If the nozzle is designed for various spray patterns, the adjustment features of the nozzle result in additional costs and complications.

OBJECTS AND SUMMARY OF THE INVENTION An object of this inventionis to provide a spray head of the type and for the purpose statedin which the airinlet passageway and the liquid-inlet passageway extend into the body of the spray head, and wherein the sealing means across the end of the liquid-inlet passageway consists of a single resilient diaphragm. As a result, a reduction in cost and simplicity of design is provided.

A further and important object of this invention is to provide a spray head of thetype stated in which the air and liquid are mixed in a mixing cavity defined in part by the diaphragm and immediately adjacent to the terminals of the air-inlet and liquid-inlet passageways. The mixed air/liquid is discharged through an outlet passageway downstream of the mixing cavity to a nozzle from which the spray is ultimately discharged. The design' of the nozzle may be simplified and adapted to a wide variety of spray patterns since the nozzle is not depended upon formixing.

An additional object of this invention is to provide a spray head of the type stated which may be disassembled for service without the need for tools, and wherein the diaphragm and its seat across the terminal of the liquid-inlet passageway are so designed that contaminants may flow through the spray head without immediately eroding the seal or preventing the seal from functioning, thereby reducing the need for frequent disassembly of the spray head for maintenance purposes.

A still further object of this invention is to provide a spray headof the type stated that utilizes a ball-swivel nozzle that can be rotated to various positions for discharging different spray patterns, such as a fine or wide conical pattern, a hollow conical pattern, fan shaped spray, or the like.

A still further object of this invention is to provide a spray head of the type stated in which the diapharagm mounting is such as to permit ready removal of the diaphragm so that it may be turned over in the eventthat the side of the diaphragm that is exposed to the flowing stream becomes partially eroded and tends to capture particles. In effect this tends to'double the Med the diaphragm before the need for replacement thereof.

In accordance with the foregoing objects the invention comprises a spray head having a body with air-inlet and liquid-inlet passageways terminating adjacent to each other within'the body and with the end liquid-inlet passageway forming a metal'seat. A flexible diaphragm is disposed across the seat, and a spring-biased piston imposes pressure upon the diaphragm to maintain the latter sealed against the seat until air of sufficient air pressure in the air-inlet passageway raises the diaphragm from the seat. A mixing chamber or cavity underlies the diaphragm and is thus defined in part by the diaphragm. The outlet passageway downstream of the mixing cavity conveys the air/liquid mixture from the mixing cavity to the spray nozzle.

BRIEF DESCRIPTION OF THE FIGURES FIG; 1 is a fragmentary view partially broken away and in section of a spray head constructed in accordance with and embodying the present invention;

FIG. 2 is another fragmentary perspective view partially brokenaway and in section of the spray head;

FIG. 3 is an exploded perspective view of the spray head, more particularly a dual-nozzle type spray head;

FIG. 4' is a sectional'view through the central axis of one type of spray nozzle that forms part of the present invention;

FIG. 5 is an end view of the nozzle of FIG. 4;

FIG. 6 shows a sectional view of a modified form of spray nozzle;

FIG. 7 is an end view of the nozzle of FIG. 6;

FIG. 8' shows a sectional view of a still further form of spray nozzle;

FIG. 9 is an end view of the nozzle of FIG. 8; and

FIG. 10 is an exploded. fragmentary perspective view of the spray head showing but still a further form of spray nozzle arrangement.

DETAILED DESCRIPTION Referring now in more detail to the drawing,.which illustrates a preferred embodiment of thepresent invention, there is shown a metal housing or body 1, which is preferably of generally block-like form. At one surface of the body are airand liquid-inlet openings marked A and L and into which conventional threaded fittings may be inserted whereby air and liquid under pressure may be supplied to the spray'head. In communication with the recessed or bottom end of the liquidinlet opening L is drilled passageway 3 that terminates within the body in a seat 5. The lower or recessed end of the opening A isin communication with a drilled passageway 7 that terminates within the body 1 adjacent to but radially offset from the seat 5.

Integral with the body 1 is a tubular cylindrical flange 9 that is coaxial with the axis of the drilled passageway 3 in the region of the seat 5. The flange 9 is also large enough in internal diameter to embrace the terminal part of the passageway 7. The flange 9' is internally threaded for receiving a cylindrical, externally threaded diaphragm retainer ring 11. A resilient and bly made from a fluorocarbon resin, which is chemically inert to many liquids. The diaphragm retainer 11 clinches the peripheral portion of the diaphragm against the shoulder 13 to form a seal thereat. It is, therefore, apparent that the diaphragm 15 constitutes a membrane-like seal or barrier that .prevents air and liquid from flowing therepast.

Axially slidable within the diaphragm retainer 11 is a piston 17 that presses against the diaphragm 15 to urge it into sealing position across the seat 5, thereby normally closing off the end of the passageway 3. The diaphragm is large as compared to the opening at the seat. The piston 7 has a machined shoulder 19 that receives the inside surface of a cap 21, and the stem 23 of the piston 17 projects slidably through a central hole 25 in the cap'21. The cap 21 has an external knurl to facilitate manual manipulation, and is internally threaded for threading onto the external thread of the flange 9. 1

Within the cap 21 is a coil compression spring 27 which bears at one end against the inside of theend wall of the cap. 21 and at its other end against the head of the piston 17. The coil spring 27 surrounds the stem of the piston and, like the piston, is coaxial with the diaphragm 15. Thus, the cap contains a subassembly comprising the piston 17 and the spring 7. This subassembly is held together by a push nut 29 that frictionally fits over the end of the piston stem 23. The amount of pressure on the piston 17 imposed by the spring 27 determines the maximum liquid holding pressure of the unit and the air pressure needed to lift the diaphragm 15 from across the seat 5. The piston 17 has a limited axial movement in accordance with its setting. Thus, depending upon how far the cap 21 is threaded onto the flange 9, the piston 17 can be set to provide controlled liquid flow or complete shut-off of the liquid. An annular machined cavity 31 underlies the diaphragm l5 and provides communication from the passageway 7 to the large underside of the diaphragm surrounding the seat 5.

When sufficient air pressure is supplied to the passageway 7, the diaphragm is lifted from the seat 5. Air and liquid will then flow into the mixing chamber or cavity at 31. This annular cavity 31 will, therefore, provide a chamber at which the air and liquid are mixed for subsequent flow to the spray nozzle. Typically, equal air and liquid pressures are used, but variations are possible within the scope of the invention.

The mixture of air and liquid in the mixing cavity underlying the diaphragm 15 is discharged through an outlet passageway 33 in the body 1. This passageway 33 terminates in a threaded hole or exit port 35 at which a nozzle assembly is located. In the form of the invention shown in FIGS. l-9, the nozzle assembly comprises a ball-nozzle 37 that is supported by a tubular nozzle seat 39. The nozzle seat 39 is sealed within the hole 35 by an O-ring 41. An externally threaded nozzle retainer 43 receives the nozzle 37 whereby a portion of the nozzle projects outwardly therefrom for presentation to the die cavity or other surface to be sprayed. As

shown, the nozzle retainer 43 has a knurled periphery to facilitate manual manipulation. When the nozzle retainer is threaded into the hole 35 so that the nozzle seat 39 bears against the O-ring 41 in sealing relation, the ball nozzle 37 is seated in place and the seal 41 prevents escape of the air-liquid mixture around the threads of the hole 35 and the nozzle retainer 43. Because the ball nozzle 37 is nested within the retainer 43 and projects slightly forwardly therefrom, the nozzle 37 may be'manually rotated for optional positioning with out disassembling the nozzle assembly. To accomplish this the retainer 43 may be loosened slightly to permit movement of the nozzle 37 when it is desired to adjust its position.

FIGS. 4-9 show a variety of nozzles which may be used with the present invention. In the nozzle 37 shown in FIGS. 4 and 5 one end portion 45 of the nozzle is conical while the other portion 47 is cylindrical. In the nozzle 37a the conical portion 45a is somewhat wider than the conical portion 45, and the opposite end of the bore of the nozzle 37a has a series of circumferentially spaced small holes 49. In the nozzle 37b the nozzle has a fan shaped slot 52 that is opposite to the conical portion 45. Other nozzle outlet configurations may also be used. Thus, there is a wide variety of nozzles, any of which may be readily installed on the spray head, may be used to provide the desired spray pattern.

In a modified form of the invention shown in FIG. 10, the nozzle comprises an adapter 53 that threads into the hole 35 and is retained by a locking ring 57. A metal-to-metal seal may be provided by the adapter fitting 53 and the thread in the hole 35. A T-fitting 59 has a stem 61 which is threaded into the internally threaded bore 63 of the adapter and forms a seal therewith. The T-fitting 59 has opposed tubes 65, 65 which may be positioned so as to direct sprays from each of the tubes intodifferent portions of die cavities of relatively complex configuration. Such an arrangement tends to reduce the total number-ofspray heads used in some situations. It should be noted, however, that the T-fitting may be replaced by a single tube or other standard fittings such as a 45 fitting, a fitting or a Y-type fitting. These are by the way of example only and not by way of limitation.

The principles of the present invention are also applicable to dual spray heads, namely those. spray heads with the nozzle projecting outwardly from opposite sides of the body 1. Rferring, for example, to FIG. 3, it will be noted that a nozzle assembly projects from the body surface 75. A like nozzle assembly within the scope of this invention may project from the opposite body surface 77. Cap 21a represents the position of the piston, diaphragm, etc. of the second nozzle, all of which components are the same as those previously described. Both nozzles share the same Liquid and Air inlet lines as shown in the upper surface of the block as shown in FIG. 3. 1

From the foregoing it will be seen that the diaphragm mechanism of the presentinvention provides effective metering as a result of the small diameter supply port at the seat 5 and the limited movement of the diaphragm 15. The thin sheet-like flow of the liquid in the mixing chamber together with the turbulent air therethrough provides excellent atomizing even for relatively viscous fluids.

Furthermore, the flow rateprovided by the limited axial movement of the diaphragm can be easily adjusted by the threaded setting of the cap 21 on the flange 9 to control the axial movement of the piston 17. This setting establishes the distance between the shoulder 19 and the inside wall of the cap 21 and thus mechanically controls diaphragm movement. However, because the diaphragm movement is small, variations in air pressure above the minimum needed to lift the diaphragm from the seat 5 will have no significant effect on diaphragm movement. Such variations in pressure serve to control the degree of atomization and the velocity of the discharged liquid particles.

The invention is claimed as follows:

1. A spray head comprising a body having an air-inlet passageway terminating in said body, a liquid-inlet passageway also terminating in said body adjacent to the terminal of said air-inlet passageway, means forming a seat at the terminal of said liquid-inlet passageway, a resilient imperforate diaphragm disposed across said seat and the terminal of said air-inlet passageway, a spring-biased member imposing pressure on said diaphragm to maintain said diaphragm sealed against said seat in the absence of sufficient air pressure in the airinlet passageway to raise the diaphragm from said seat, said liquid inlet passageway being free of said springbiased member, a mixing cavity defined in part by said diaphragm and exposed to both of said passageway terminals upon sufficient air pressure being in said airinlet passageway to raise said diaphragm from said seat, said diaphragm being secured around its entire periphery to constitute a membrane-like'barrier preventing flow of liquid and air therepast from said mixing cavity,

an outlet passageway downstream of said mixing cavity for conveying an air-liquid mixture from said mixing cavity, and a nozzle in communication with said outlet passageway for spraying the mixture conveyed thereto.

2. A spray head comprising a body having anair-inlet passageway terminating in said body, a liquid-inlet passageway also terminating in said body adjacent to the terminal of said air-inlet passageway, means forming a seat at the terminal of said liquid-inlet passageway, a resilient diaphragm disposed across said seat and the terminal of said air-inlet passageway, a spring-biased member imposing pressure on said diaphragm to maintain said diaphragm sealed against said seat in the absence of sufficient air pressure in the air-inlet passageway to raise the diaphragm from said seat, a mixing cavity defined in part by said diaphragm and exposed to both of said passageway terminals upon sufficient air pressure being in said air-inlet passageway to raise said diaphragm from said seat, an outlet passageway downstream of said mixing cavity for conveying an air-liquid mixture from said mixingcavity, and a nozzle in communication with said outlet passageway for spraying the mixture conveyed thereto; and in which said diaphragm is imperforate, said spring-biased member is a spring biased-piston, and said diaphragm is peripherally clamped to said body against a diaphragm seat therein.

3. A spray head according to claim 1 in which the terminal of the liquid-inlet passageway is small in crosssectional area as compared to the cross-sectional area of the face of the diaphragm that is presented thereto.

4. A spray head according to claim 1 in which said nozzle comprises swivelly mounted ball member having an opening therethrough, one end portion of the opening being conical, and an'opposite end portion being of different shape whereby the ball member may be op- I terminal of said air-inlet passageway, means forming a seat at the terminal of said liquid-inlet passageway, a resilient diaphragm disposed across said seat'and the terminal of .said air-inlet passageway, a spring-biased member imposing pressure on said diaphragm to maintain said diaphragm sealed against said seat in the absence of sufficient air pressure in the air-inlet passageway to raise the diaphragm from said seat, a mixing cavity defined in part by said diaphragm and exposed to both of said passageway terminals upon sufficient air pressure being in said air-inlet passageway to raise said diaphragm from said seat, an outlet passageway downstream of said mixing cavity for conveying an air-liquid mixture from said mixing cavity, and a nozzle in communication with said outlet passageway for spraying the mixture conveyed thereto; and in which said body has a shoulder surrounding said passageway terminals, said diaphragm is peripherally supported on said shoulder, a tubular flange is on said body and surrounds said shoulder, a clamping ring is threaded into said flange and peripherally clinches said diaphragm against said shoulder, said spring-biased member is a piston in said clamping ring that is biased by a spring, and a cap is threaded onto said flange and provides an abutment for one end of the spring, the threaded position of said cap on said tubular flange determining the amount of axial movement permitted by said piston.

7. A spray head according to claim 6 in which said mixing cavity is of a shape to provide a sheet-like flow of liquid therethrough.

8. A spray head comprising a body having an air-inlet passageway terminating in said body, a liquid-inlet passageway also terminating in said body adjacent to the terminal of said air-inlet passageway, means forming a seat at the terminal of said liquid-inlet passageway, a resilient diaphragm disposed across said seat and the terminal of said air-inlet passageway, a spring-biased member imposing pressure on said diaphragm to maintain said diaphragm sealed against said seat in the absenceof sufficient air pressure in the air-inlet passageway to raise the diaphragm from said seat, a diaphragm seat in said body and supporting th'e'periphery of said diaphragm, a clamping ring removably secured to said body and imposing pressure against said diaphragm to seal the diaphragm in place on said seat, a mixing cavity defined in part by said diaphragm and exposed to both -of said passageway terminals upon sufficient air pressure being in said air-inlet passageway to raise said diaphragm from said-seat, an outlet passageway downstream of said mixing cavity for conveying an air-liquid mixture from said mixing cavity, and a nozzle in communication with said outlet passageway for spraying the mixture conveyed thereto.

9. A spray head according to claim 8 in which said spring-biased means is within said clamping ring.

10. A spray head comprising a body having an airinlet passageway terminating in said body, a liquid-inlet passageway also terminating in said body adjacent to the terminal of said air-inlet passageway, means forming a seat at the terminal of said liquid-inlet passageway, a resilient diaphragm disposed across said seat and the terminal of said air-inlet passageway, a springbiased member imposing pressure on said diaphragm to maintain said diaphragm sealed against said seat in the absence of sufficient air pressure in the air-inlet passageway to raise the diaphragm from said-seat, a mixing cavity defined in part by said diaphragm and exposed to both of said passageway terminals upon sufficient air pressure being in said air-inlet passageway to raise said diaphragm from said seat, said diaphragm being an imperforate member-like member having opposed sides of such configuration as to be operable when either side is exposed to the air-liquid mixture, means removably mounting said diaphragm in said body so that upon removal of said means the diaphragm may be selecthe mixture conveyed thereto.

Claims

1. A spray head comprising a body having an air-inlet passageway terminating in said body, a liquid-inlet passageway also terminating in said body adjacent to the terminal of said airinlet passageway, means forming a seat at the terminal of said liquid-inlet passageway, a resilient imperforate diaphragm disposed across said seat and the terminal of said air-inlet passageway, a spring-biased member imposing pressure on said diaphragm to maintain said diaphragm sealed against said seat in the absence of sufficient air pressure in the air-inlet passageway to raise the diaphragm from said seat, said liquid inlet passageway being free of said spring-biased member, a mixing cavity defined in part by said diaphragm and exposed to both of said passageway terminals upon sufficient air pressure being in said air-inlet passageway to raise said diaphragm from said seat, said diaphragm being secured around its entire periphery to constitute a membrane-like barrier Preventing flow of liquid and air therepast from said mixing cavity, an outlet passageway downstream of said mixing cavity for conveying an airliquid mixture from said mixing cavity, and a nozzle in communication with said outlet passageway for spraying the mixture conveyed thereto.

2. A spray head comprising a body having an air-inlet passageway terminating in said body, a liquid-inlet passageway also terminating in said body adjacent to the terminal of said air-inlet passageway, means forming a seat at the terminal of said liquid-inlet passageway, a resilient diaphragm disposed across said seat and the terminal of said air-inlet passageway, a spring-biased member imposing pressure on said diaphragm to maintain said diaphragm sealed against said seat in the absence of sufficient air pressure in the air-inlet passageway to raise the diaphragm from said seat, a mixing cavity defined in part by said diaphragm and exposed to both of said passageway terminals upon sufficient air pressure being in said air-inlet passageway to raise said diaphragm from said seat, an outlet passageway downstream of said mixing cavity for conveying an air-liquid mixture from said mixing cavity, and a nozzle in communication with said outlet passageway for spraying the mixture conveyed thereto; and in which said diaphragm is imperforate, said spring-biased member is a spring biased-piston, and said diaphragm is peripherally clamped to said body against a diaphragm seat therein.

3. A spray head according to claim 1 in which the terminal of the liquid-inlet passageway is small in cross-sectional area as compared to the cross-sectional area of the face of the diaphragm that is presented thereto.

4. A spray head according to claim 1 in which said nozzle comprises swivelly mounted ball member having an opening therethrough, one end portion of the opening being conical, and an opposite end portion being of different shape whereby the ball member may be optionally rotated to provide different spray patterns.

5. A spray head according to claim 1 in which said nozzle comprises a tube member.

6. A spray head comprising a body having an air-inlet passageway terminating in said body, a liquid-inlet passageway also terminating in said body adjacent to the terminal of said air-inlet passageway, means forming a seat at the terminal of said liquid-inlet passageway, a resilient diaphragm disposed across said seat and the terminal of said air-inlet passageway, a spring-biased member imposing pressure on said diaphragm to maintain said diaphragm sealed against said seat in the absence of sufficient air pressure in the air-inlet passageway to raise the diaphragm from said seat, a mixing cavity defined in part by said diaphragm and exposed to both of said passageway terminals upon sufficient air pressure being in said air-inlet passageway to raise said diaphragm from said seat, an outlet passageway downstream of said mixing cavity for conveying an air-liquid mixture from said mixing cavity, and a nozzle in communication with said outlet passageway for spraying the mixture conveyed thereto; and in which said body has a shoulder surrounding said passageway terminals, said diaphragm is peripherally supported on said shoulder, a tubular flange is on said body and surrounds said shoulder, a clamping ring is threaded into said flange and peripherally clinches said diaphragm against said shoulder, said spring-biased member is a piston in said clamping ring that is biased by a spring, and a cap is threaded onto said flange and provides an abutment for one end of the spring, the threaded position of said cap on said tubular flange determining the amount of axial movement permitted by said piston.

8. A spray head comprising a body having an air-inlet passageway terminating in said body, a liquid-inlet passageway also terminating in said body adjacent to the terminal of saiD air-inlet passageway, means forming a seat at the terminal of said liquid-inlet passageway, a resilient diaphragm disposed across said seat and the terminal of said air-inlet passageway, a spring-biased member imposing pressure on said diaphragm to maintain said diaphragm sealed against said seat in the absence of sufficient air pressure in the air-inlet passageway to raise the diaphragm from said seat, a diaphragm seat in said body and supporting the periphery of said diaphragm, a clamping ring removably secured to said body and imposing pressure against said diaphragm to seal the diaphragm in place on said seat, a mixing cavity defined in part by said diaphragm and exposed to both of said passageway terminals upon sufficient air pressure being in said air-inlet passageway to raise said diaphragm from said seat, an outlet passageway downstream of said mixing cavity for conveying an air-liquid mixture from said mixing cavity, and a nozzle in communication with said outlet passageway for spraying the mixture conveyed thereto.

10. A spray head comprising a body having an air-inlet passageway terminating in said body, a liquid-inlet passageway also terminating in said body adjacent to the terminal of said air-inlet passageway, means forming a seat at the terminal of said liquid-inlet passageway, a resilient diaphragm disposed across said seat and the terminal of said air-inlet passageway, a spring-biased member imposing pressure on said diaphragm to maintain said diaphragm sealed against said seat in the absence of sufficient air pressure in the air-inlet passageway to raise the diaphragm from said seat, a mixing cavity defined in part by said diaphragm and exposed to both of said passageway terminals upon sufficient air pressure being in said air-inlet passageway to raise said diaphragm from said seat, said diaphragm being an imperforate member-like member having opposed sides of such configuration as to be operable when either side is exposed to the air-liquid mixture, means removably mounting said diaphragm in said body so that upon removal of said means the diaphragm may be selectively installed within said body with either side thereof presented to said mixture, an outlet passageway downstream of said mixing cavity for conveying an air-liquid mixture from said mixing cavity, and a nozzle in communication with said outlet passageway for spraying the mixture conveyed thereto.