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Title:
APPARATUS AND METHOD FOR DELIVERING A TREATMENT FLUID
Document Type and Number:
WIPO Patent Application WO/2003/008001
Kind Code:
A1
Abstract:
The present invention provides an apparatus for delivering a treatment fluid to a space such as within an air conditioning system of a commercial or residential premises. The apparatus comprises at least one atomising means for passing atomised treatment fluid into the space, a vessel for holding the treatment fluid, at least one delivery line for delivering treatment fluid from the vessel to the at least one atomising means, and control means for controlling delivery of atomised fluid to the space. The atomising means delivers atomised fluid to the space in a form that allows vaporisation of the fluid in the space. In preferred embodiments, the fluid is atomised to an average fluid drop size in the range of 5-10 microns. This allows vaporisation of the treatment fluid in the space which results in substantial avoidance of build up of the treatment fluid or residues thereof on the walls of the space.

Inventors:
DANGERFIELD ROBERT (AU)
Application Number:
PCT/AU2002/000972
Publication Date:
January 30, 2003
Filing Date:
July 19, 2002
Export Citation:
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Assignee:
PURE AS AIR AUSTRALIA PTY LTD (AU)
DANGERFIELD ROBERT (AU)
International Classes:
A61L9/015; A61L9/14; F24F3/16; (IPC1-7): A61L9/14; A61L9/015; F24F3/12; F24F3/16
Domestic Patent References:
WO1997010475A11997-03-20
WO1988010122A11988-12-29
Foreign References:
US6447816B12002-09-10
US6027030A2000-02-22
US5727732A1998-03-17
US5667733A1997-09-16
EP0485682B11995-08-16
US4272014A1981-06-09
FR2448930A11980-09-12
Attorney, Agent or Firm:
Freehills, Carter Smith Beadle (MLC Centre 19-29 Martin Plac, Sydney New South Wales 2000, AU)
Download PDF:
Claims:
Claims
1. An apparatus for delivering a treatment fluid to a space comprising at least one atomising means for passing atomised treatment fluid into the space, a vessel for holding the treatment fluid, at least one delivery line for delivering treatment fluid from the vessel to the at least one atomising means, and control means for controlling delivery of atomised fluid to the space, wherein said atomising means delivers atomised fluid to the space in a form that allows vaporisation of the fluid in the space.
2. Apparatus as claimed in claim 1 wherein the atomised fluid is delivered to the space in the form of a fog of fluid having an average fluid drop size of 510 microns.
3. Apparatus as claimed in claim 1 or claim 2 further comprising compressor means for supplying pressurised gas to the vessel.
4. Apparatus as claimed in claim 3 wherein the compressor means comprises an air compressor.
5. Apparatus as claimed in claim 3 or claim 4 wherein the atomising means comprises an atomising nozzle having an outlet positioned to cause atomised fluid to pass into the space.
6. Apparatus as claimed in claim 5 wherein a pressurised gas is mixed with treatment fluid in the atomising means to cause the treatment fluid exiting the nozzle to be atomised.
7. Apparatus as claimed in claim 6 wherein pressurised gas is supplied to the atomising means from a compressor.
8. Apparatus as claimed in claims 6 or 7 wherein the atomising means comprises a nozzle body having an atomising nozzle and a nozzle pin, said nozzle pin being selectively operable to allow the treatment fluid and the pressurised gas to be mixed in the atomising means and to be delivered from the nozzle as a fine spray.
9. Apparatus as claimed in any one of claims 6 to 8 further comprising pressurised gas control means for controlling delivery of pressurised gas to the atomising means.
10. Apparatus as claimed in claim 10 wherein the pressurised gas control means comprises a control valve under the control of the control means.
11. Apparatus as claimed in any one of claims 6 to 10 further comprising treatment fluid control means for controlling delivery of the treatment fluid to the atomising means.
12. Apparatus as claimed in claim 11 wherein the treatment fluid control means comprises a control valve in the delivery line for delivering treatment fluid to the atomising means.
13. Apparatus as claimed in claim 11 wherein the treatment fluid control means comprises an inlet control valve for the atomising means.
14. Apparatus as claimed in any one of the preceding claims wherein the control means controls the supply of pressurised gas and treatment fluid to the atomising means.
15. Apparatus as claimed in any one of the preceding claims wherein the apparatus supplies treatment fluid to an air conditioning system and the control means is operable to ensure that treatment fluid is delivered to the air conditioning system only when the air conditioning system is operating.
16. Apparatus as claimed in claim 15 wherein the control means includes detector means for detecting a state of operation of the air conditioning system and safety lockout means for ensuring that the treatment fluid is not supplied if the detector means detects that the air conditioning system is not operating.
17. Apparatus as claimed in any one of the preceding claims further comprising a treatment fluid detecting means for detecting the amount of treatment fluid in the vessel.
18. A method for delivering a treatment fluid to a space comprising the steps of providing a source of treatment fluid, providing a source of pressurised gas, delivering gas to an atomising means, delivering the treatment fluid to the atomising means and atomising the treatment fluid and delivering atomised treatment fluid to the space.
19. A method as claimed in claim 18 wherein the step of delivering the treatment fluid to the atomising means comprises the steps of providing pressurised gas to a vessel holding the treatment fluid and opening treatment fluid regulation means to thereby enabled pressurised treatment fluid from the vessel to be delivered to the atomising means.
20. A method as claimed in claim 18 or claim 19 wherein the treatment fluid is delivered to an air conditioning system and the method further comprises the steps of detecting a state of operation of the air conditioning system and delivering treatment fluid to the air conditioning system only in the event that the air conditioning system is detected to be in an operating condition.
21. A method as claimed in any one of claims 18 to 20 further comprising delivering pressurised gas to the atomising means a short time before delivering the treatment fluid to the atomising means at the commencement of a delivery cycle.
Description:
Apparatus and method for delivering a treatment fluid Field of the invention The present invention relates to an apparatus and a method for delivering a treatment fluid to a space, such as a conduit or a room. The present invention is especially suitable for supplying tea tree oil to an air conditioning system, although the invention should not be considered to be restricted solely to that use.

Background of the invention Many commercial and residential buildings include air conditioning systems to regulate the environment inside the building. Such air conditioning systems typically comprise an air conditioning plant having a fan or blower that passes the conditioned air into duct work that extends throughout the building. The duct work includes ducting or conduits having a number of outlets (frequently called"registers") that allow the conditioned air to be fed into the internal space within the building.

Air conditioning is today seen as almost an essential requirement for many commercial and residential buildings for ensuring the comfort of people who work and/or live inside the building. However, air conditioning does have several drawbacks, including the tendency to spread germs throughout the building. Moreover, the ducting or conduits can also become quite dirty and dusty over time, which is undesirable.

In order to minimise the undesirable characteristics of air conditioning systems, it has been proposed to supply a small amount of a treatment fluid to the air conditioning system, which treatment fluid can dispel some of those undesirable characteristics. It is known that tea tree oil has disinfectant and antibiotic properties as well as having a general agreeable odour.

Consequently, it has been proposed to inject tea tree oil into air conditioning systems in an attempt to address the undesirable characteristics of air conditioning systems mentioned above.

Tea tree oil vapour can be purchased commercially in compressed form. Typically, the commercially available form of tea tree oil is purchased as a cylinder of compressed carbon dioxide having tea tree oil therein. The pressure inside the cylinder is such that the carbon dioxide and the tea tree oil are present in liquid form. When the mixture leaves the cylinder, the

carbon dioxide vaporises and causes some flash evaporation of the tea tree oil. However, tea tree oil has a relatively low vapour pressure and therefore it has been found that noticeable quantities of liquid tea tree oil are also entrained with the carbon dioxide.

Previous apparatus for injecting tea tree oil into air conditioning systems have operated in a fashion that resulted in liquid tea tree oil being passed to the first register of the air conditioning system. Significant quantities of liquid tea tree oil were also deposited in the ducting, which caused maintenance problems due to the corrosive nature of the tea tree oil on metal.

Summary of the invention In a first aspect, the present invention provides an apparatus for delivering a treatment fluid to a space comprising at least one atomising means for passing atomised treatment fluid into the space, a vessel for holding the treatment fluid, at least one delivery line for delivering treatment fluid from the vessel to the at least one atomising means, and control means for controlling delivery of atomised fluid to the space, wherein said atomising means delivers atomised fluid to the space in a form that allows vaporisation of the fluid in the space.

The system most suitably delivers a fog of fluid to the space, preferably with an average fluid drop size in the range of 5-10 microns. This allows vaporisation of the treatment fluid in the space which results in substantial avoidance of build up of the treatment fluid or residues thereof on the walls of the space.

Preferably, the apparatus further comprises compressor means for supplying pressurised gas to the vessel. The compressor means is most suitably an air compressor. The compressor means supplies pressurised gas to the vessel which pressurises the vessel. This can then cause the treatment fluid to be delivered from the vessel to the atomising means.

The atomising means may comprise an atomising nozzle having an outlet positioned to enable atomised treatment fluid to pass into the space. The atomising means is preferably of the type in which a pressurised gas is mixed with the treatment fluid to cause the treatment fluid to exit the nozzle as a dispersion of fine fluid particulates. In this embodiment, the treatment fluid and pressurised gas are delivered to the atomising means and mixed prior to expiration through

the nozzle. In this embodiment, the compressor suitably provides pressurised gas to the atomising means.

The atomising means most preferably comprises a nozzle body having an atomising nozzle and a nozzle pin. Operation of the nozzle pin from a first position to a second position (suitably from a closed to an open position) allows the treatment fluid and the pressurised gas to be mixed in the atomising means and to be delivered from the nozzle as a fine spray.

The apparatus preferably also includes a pressurised gas control means for controlling delivery of pressurised gas to the atomising means. The pressurised gas control means preferably comprises a control valve under the control of the control means. The control valve suitably comprises a solenoid, particularly an electrically or electronically operated solenoid.

The apparatus may also further comprise a treatment fluid control means for controlling delivery of the treatment fluid to the atomising means. The treatment fluid control means may comprise a control valve in the delivery line for treatment fluid. More preferably, the treatment fluid control means comprises an inlet control valve for the atomising means. The inlet control valve may comprise the nozzle pin.

Most preferably, the nozzle pin is controlled by a three way solenoid. When the three way solenoid is energised, the nozzle pin is opened, which allows the treatment fluid and the pressurised gas to mix and to be delivered as a fine spray from the atomising means.

The control means is preferably an electronic control means or a micro processor or computer control means. The control means controls the supply of pressurised gas and treatment fluid to the atomising means. In preferred embodiments of the invention, the control means controls the operation of the solenoids of the apparatus. Where the apparatus is used to supply treatment fluid to an air conditioning system, the control means most preferably operates such that the apparatus will only deliver treatment fluid from the atomising means when the air conditioning is turned on. In this regard, the control means may further include detector means for detecting a state of operation of the air conditioning system and safety lockout means for ensuring that the treatment fluid is not supplied if the detector means detects that the air conditioning system is not operating. The detector means may comprise an input from the air conditioning system to the control means.

The control means may also include at least one programmed treatment cycle. The treatment cycle may control the duration of delivery of the treatment fluid and/or the dosage of treatment fluid to the space. The treatment cycles may include an"on"period during which the treatment fluid is delivered to the space, followed by an"off"period. If the control means has more than one treatment cycle, each different treatment cycle may deliver a different dosage of treatment fluid to the space. The delivery of different dosages of treatment fluid to the space is most suitably achieved by varying the"on"time of the different treatment cycles. This enables the treatment fluid to be delivered at a constant rate when the"on"cycle is operating. However, in treatment cycles that are designed to deliver greater dosages of treatment fluid to the space, the"on"period is larger than for treatment cycles designed to deliver lower dosages of treatment fluid.

The apparatus may further include a treatment fluid detecting means for detecting the amount of treatment fluid in the vessel. This most suitably comprises a level detector located in the vessel. The level detector may be connected to an output to indicate the level of treatment fluid in the detector. An alarm may be provided if the level of treatment fluid in the vessel falls below a specified level.

In a second aspect, the present invention provides a method for delivering a treatment fluid to a space comprising the steps of providing a source of treatment fluid, providing a source of pressurised gas, delivering pressurised gas to an atomising means, delivering the treatment fluid to the atomising means and atomising the treatment fluid and delivering atomised treatment fluid to the space.

Preferably, the step of delivering the treatment fluid to the atomising means comprises the steps of providing pressurised gas to a vessel holding the treatment fluid and opening treatment fluid regulation means to thereby enabled pressurised treatment fluid from the vessel to be delivered to the atomising means.

Preferably, the method of the present invention delivers a treatment fluid to an air conditioning system. In this embodiment, the method further comprises the steps of detecting a state of operation of the air conditioning system and delivering treatment fluid to the air

conditioning system only in the event that the air conditioning system is detected to be in an operating condition.

In a third embodiment, the method further comprises delivering pressurised gas to the atomising means a short time before delivering the treatment fluid to the atomising means at the commencement of a delivery cycle. By delivering the pressurised gas to the atomising means a short time before the treatment fluid is delivered, the atomising means is purged and the pressurised gas, which acts as an atomising gas, ensures that the treatment fluid is atomised as soon as it is delivered to the atomising means.

Brief description of the drawings Figure 1 is a flow sheet showing an apparatus in accordance with the present invention; Figure 2 is a sematic diagram of an apparatus in accordance with the present invention; Figure 3a is a generally similar view to that of figure 2, but with the main control unit shown partly in cross section; Figure 3b is a cross-sectional, right side elevation of Figure 3a; Figure 3c is a rear, cross-sectional elevation of Figure 3a; Figure 3d is a cross-sectional, left side elevation of Figure 3a; Figure 4 is a similar view to figure 2, but showing the apparatus delivering treatment fluid to two different spaces; Figure 5 is a side view of the nozzle assembly used in the present invention fixed in position for delivering treatment fluid to an air conditioning duct; Figure 6 is a top view of the bracket used to fix the nozzle assembly to an air conditioning duct; Figure 7 is a view of an air injector control unit as used in apparatus in accordance with the present invention; Figure 8 is a view of the air injector control unit of figure 7 with the front panel removed; and Figure 9 is a bottom view of the air injector control unit.

Detailed description of the embodiments In describing the accompanying drawings, it will be appreciated that the drawings show preferred embodiments of the present invention and that the invention should not be considered to be limited to the embodiments shown in those drawings. The drawings are provided for the purposes of illustrating the present invention.

The apparatus shown in figures 1 to 9 is provided for delivering tea tree oil to one or more ducts of an air conditioning system. The tea tree oil is delivered in the form of a fine spray which can pass along the air conditioning ducts and through room registers to enter a room. The tea tree oil acts to disinfect the ducts and room, thereby reducing the bacterial and viral load distributed throughout the air conditioning system. The tea tree oil may reduce the presence of cold and flu viruses in the air conditioning system. It may even be able to treat the air conditioning system to reduce or remove the presence of bacteria, such as legionella bacteria.

Figure 1 shows a schematic flow sheet of an apparatus in accordance with the present invention. The apparatus of figure 1 includes a pressure vessel 10 for holding a tea tree oil containing treatment fluid. The tea tree oil containing treatment fluid preferably comprises a water soluble tea tree oil at 5% mix. The pressure vessel 10 includes a liquid level switch 12 for detecting the liquid level in the pressure vessel 10.

The apparatus also includes an air compressor 14. Air compressor 14 may suitably comprise an electrically operated air compressor, or indeed any other suitable air compressor known to be suitable to the man skilled in the art. The air compressor 14 provides compressed air to the pressure vessel 10 via line 16. Line 16 includes an air regulator 18 for controlling the pressure of the compressed air supplied to the pressure vessel 10. An in-line air filter 19 is provided to remove particulates from the compressed air.

The apparatus also includes an atomising means 20. The atomising means 20 is mounted to an air conditioning duct such that the atomising means can deliver atomised tea tree oil containing fluid to the air conditioning duct. This will be described in more detail hereunder.

The pressure vessel 10 includes a fluid delivery line 22 for delivering the tea tree oil containing fluid from the pressure vessel 10 to the atomising means 20. Fluid delivery line 22

includes an inline liquid strainer 24 for straining solid particulates from the tea tree oil containing fluid. This assists in preventing blockages of the atomising means 20.

The apparatus further includes a pressurised air delivery line 26 for delivering pressurised air from the air compressor 14 to the atomising means 20. The pressurised air delivery line 26 includes an air regulator 28 for regulating the pressure at which the pressurised air is delivered to the atomising means. The pressurised air delivery line 26 also includes a two- way solenoid or solenoid valve 30 for regulating the delivery of pressurised air to the atomising means 20.

The apparatus also includes a second pressurised air delivery line 32 for delivering air to a nozzle pin of the nozzle. The pressurised air delivered through second pressurised air delivery line 32 controls the operation of the nozzle pin, which in turn controls the delivery of tea tree oil containing fluid to the atomising means. The second pressurised air delivery line 32 includes a three-way solenoid 34 (which may be a solenoid valve) for controlling the delivery of pressurised air to the nozzle pin.

Figure 2 shows a schematic diagram of the apparatus shown in the flow sheet of figure 1. The apparatus shown in figure 2 includes a main control unit 36 which comprises an outer cabinet 38 mounted on legs 40. If desired, legs 40 may be provided with wheels or castors for easy transport of the main control unit 36. If wheels or castors are provided, they should be lockable wheels or castors so that the main control unit 36 does not move during operation.

Alternatively, the wheels or castors may be removable.

The main control unit 36 includes pressure vessel 10, air compressor 14, inline liquid strainer 22, and the various regulators shown in figure 1. The main control unit 36 includes a service door 42 for providing access to pressure vessel 10. The main control unit 36 also includes a service door 44 for providing access to the regulators and inline strainer as shown in figure 1.

The main control unit 36 also includes a display panel 46. Although not shown in figure 2, the main control unit also includes a printed circuit board which comprises part of the control means for controlling the delivery of the tea tree oil containing fluid to the atomising means.

The main control unit 36 also includes an electrical connector 48 for connecting to mains electrical power.

The apparatus of the present invention also includes an injector control unit 50. Injector control unit 50 is connected to the atomising means 20 and also houses the two-way solenoid 30 and three-way solenoid 34. The injector control unit also includes a printed circuit board which forms part of the control means of the apparatus. The injector control unit also has a display panel 52.

As clearly shown in figure 2, the main control unit 36 is positioned on a floor, most suitably in the plant room of a building. The injector control unit is mounted to a hole formed in the side of an air conditioning duct 54. This will be explained in greater detail with reference to figure 5. Interconnecting tubing, denoted generally be reference numeral 56, is connected between appropriate outputs from main control unit 36 and associated inputs on injector control unit 50. The interconnecting tubing 56 allows for the transfer of the tea tree oil containing fluid and pressurised air from the main control unit 36 to the injector control unit 50. A plug-in electrical connector 58 also extends from the main control unit 36 to the injector control unit 50 to thereby provide electrical power to the injector control unit. It will be appreciated that the injector control unit may also be provided with a separate plug-in electrical connector for connection directly to the electrical mains supply in lieu of plug-in connector 58.

The arrangement of the pressure tank 10, compressor 14, inline strainer 22 and air regulators 18, 28 inside main control unit 36 is more clearly shown in figures 3a to 3d. It can also be seen that the main control unit 36 includes an air intake 60 for the air compressor 14.

The air intake 60 preferably includes a fine mesh to remove larger dust particles and fluff from the air.

Figure 4 shows another embodiment of the apparatus of the present invention, but set up to allow tea tree oil containing fluid to be delivered to two injector control units. The apparatus shown in figure 4 includes a main control unit 36, which is identical to the main control unit 36 shown in figures 2 and 3. The apparatus also includes a first injector control unit 50A which is mounted to the side of air conditioning duct 54A and a second injector control unit 50B which is mounted to the side of a second air conditioning duct 54B. Injector control units 50A and 50B

are identical to injector control unit 50 shown in figure 2. A first set of interconnecting tubing 56A is used to deliver tea tree oil containing fluid and pressurised air from main control unit 36 to first injector control unit 50A. A second set of interconnecting tubing 56B extends from first injector control unit 50A to second injector control unit 50B. Interconnecting tubing 56B allows the delivery of tea tree oil containing fluid and pressurised air to second injector control unit 50B. Electrical plug-in 58A delivers electrical power from the main control unit 36 to first injector control unit 50A. Electrical plug-in 58B delivers electrical power from the main control unit to the second injector control unit 50B.

Figures 5 and 6 show the atomising means and nozzle assembly that is used in the present invention, and the preferred method of fixing the atomising means to the air conditioning duct. With reference to figures 5 and 6, the air conditioning duct has a wall 62. A suitably sized hole is cut in the wall 62 of air conditioning duct. Fixing bracket, in the form of a plate 64 having suitable fixing holes 66 and downwardly depending walls 67,69 is positioned over the hole formed in the wall 62 of the air conditioning duct. Fixing screws 68 are used to fix the plate 64 to the wall of the duct 62. A gasket 70 is formed between the fixing plate 64 and the wall 62 of the air conditioning duct. The gasket may suitably be formed by use of a silicone sealant. As shown in figure 5, downwardly depending walls 67,69 extend through the hole formed in duct 62.

As best shown in figure 6, fixing plate 64 has a hole 72 formed therein, which hole is sized sufficiently large to enable nozzle body 74 to pass therethrough. The nozzle body 74 holds the spray head assembly 76. A nozzle securing bracket 78 holds the nozzle body in the desired orientation. Spray head 76 is positioned in and supported by a suitable opening in wall 67. A gasket, such as a soft washer 87, seals the opening in wall 67.

Nozzle securing bracket 78 is best shown in figure 5A. As can be seen, bracket 78 includes lower bracket part 79 and upper bracket part 81 removably fastened together by screws 83. Bracket parts 79,81 define an opening 83 that holds the nozzle body 74. Screws 81, 83 are suitably screwed into wall 89. Bracket 79,81 are suitably made from an elastomeric material.

The nozzle body 74 includes an inlet 80 through which pressurised air can pass. A similar inlet (not shown) for the tea tree oil containing fluid is also provided at a position that is

circumferentially spaced from inlet 80. Airflow tube can be easily connected to tubing 56 for ease of installation.

The nozzle body 74 also has a nozzle pin 82 for controlling the flow of tea tree oil containing fluid to the spray head assembly 76.

Figure 7 shows a diagram of the injector control unit 50 used in the present invention.

The injector control unit 50 includes an outer cabinet 84 having a front door 86a. A key lock 88 is provided in order to enable the front door 86 to be locked.

The front door of the cabinet 84 includes indicating lamps 94 which indicate the running status of the system.

As best shown in figures 7 and 8, the cabinet enclosure 84 also includes a back door 86b having mounting holes 96 for mounting the cabinet 84 to the airconditioning duct. The fixing holes 96 are most preferably arranged to overlie the fixing holes 66 in fixing plate 64. Back door 86b includes an access hole 89 to provide access to the nozzle assembly.

The main body 91 of cabinet enclosure 84 is hingedly connected to both the back door 86b and the front door 86a. Both back door 86b and front door 86a can be closed and locked.

If access to the nozzle body 74 is required, for example for maintenance purposes, back door 86b may be unlocked and main body 91 of cabinet enclosure 84 may be swung out of the way.

If access to the internal space of the main body 91 of cabinet enclosure 84 is required, front door 86a may be unlocked and opened.

As best shown in figure 8, the rear wall of main body 91 has an opening 93 therethrough through which the piping that is connected to nozzle body 74 can pass.

Figure 9 shows a schematic view of the cabinet enclosure 84 with the front door 86a in the open position. As can be seen from figure 9, fluid delivery line 22 is provided with an optional valve 23 to enable the fluid delivery line to be manually closed, for example for maintenance purposes when it is desired to stop delivering treatment fluid to the nozzle body.

Line 22 then passes into opening 93 and is connected to nozzle body 74. Similarly, pressurised air delivery line 26 is connected to divider 27. One outlet from divider 27 is connected to regulator 28 and 2-way solenoid 30 and thereafter to the nozzle body 74. The other outlet from

divider 27 is connected to three-way solenoid 34 and thereafter to the nozzle pin of nozzle body 74.

The cabinet 84 also has a level switch 90 and a test button 92. Microprocessor 99 is mounted in cabinet 84 and controls operation of the apparatus.

The bottom panel 100 of the cabinet is also provided with an opening 102 in order to allow the interconnecting tubing 56 to pass into the cabinet 84 and to be connected, as appropriate to the nozzle body 74. The bottom panel 100 also includes a plug-in connector socket 104 for enabling the plug-in connector 58 to be connected to the injector control unit 50.

Air flow switch 110 is provided to detect air flow when the air conditioning is running.

Air flow switch 110 initiates the injection control unit micro-processor to operate. Air flow tube 85 extends into the air conditioning duct (see Figures 5 and 6A) and air flow tube 85 is connected via suitable tubing to air flow switch 110. When the air conditioning is running, air travels up air flow tube 85 and into air flow switch 110.

Operation of the apparatus shown in figures 1 to 9 will now be described: Installation The main control unit can be free-standing or positioned against a wall. The main control unit is mounted on leg supports to enable access underneath for cleaning.

The injector control unit is installed by the use of a hole saw cutting a hole in the air conditioning duct to accommodate the nozzle assembly. The nozzle assembly can be rotated to suit the direction of airflow. Once positioned, the nozzle assembly is fixed to the duct with fixing screws and the use of silicone sealant to form a gasket seal between the duct and the assembly. The injector control unit is then fixed to the duct over the nozzle assembly. The interconnecting tubing for both the tea tree oil containing fluid and the pressurised air is installed between the main control unit and the injector control unit. Standard electrical cables with male and female 240 volt plugs are connected between the main controller and injector control unit. Where multiple injectors are required, the interconnecting tubing for both air and the tea tree oil containing fluid are provided as a looped connection between each injector control unit, with power supply coming from the main control unit.

Operation The pressure vessel 10 is filled with a water soluble tea tree oil mixture and the main control unit 36 is plugged via electrical connector 48 into a 240 volt power socket. The injector control unit 50 has a free contact available to receive an input from the air conditioning unit.

The air compressor is activated once an"on"switch on display panel 46 of main control unit 36 is turned on. The air compressor 14 is preferably fitted with an automatic cut-out when the system reaches full capacity.

The injector system is initiated when the"on"switch on main control unit 36 is turned on and when the injection control unit detects that the air conditioning is running. The injector control unit will only operate when the air conditioning unit is turned on. In this regard, the control means in the injector control unit 50 and/or the main control unit 36 includes a detector for detecting the state of the air conditioning unit. If the detector detects that the air conditioning unit is turned off, operation of the injector control unit is disabled.

When the compressor 14 is turned on, compressed air pressurises the pressure tank 10 via regulator 18. Regulator 18 is preferably set at two bar (29 psi).

The air compressor also provides pressurised air to the two-way solenoid via regulator 28 set at 2.1 bar (30 psi). Compressed air is also provided directly from the compressor at about 6 to 8 bar (84 to 116 psi) to the three-way solenoid 34 that operates the nozzle pin 82. When nozzle pin 82 is triggered, the tea tree oil containing fluid and the atomising air are allowed to mix at the spray head 76.

When the control unit asks for atomising to commence, the two-way solenoid 30 is energised to open approximately 1 second before the three-way solenoid 34. This purges air from the system and ensures that atomising air is flowing to the spray head 76 before the tea tree oil containing fluid is supplied to the spray head. This maximises the atomising efficiency of the fluid. The three-way solenoid then energises, which opens the nozzle pin 82, which allows the tea tree oil containing fluid to mix with the atomising air. The tea tree oil containing fluid then passes through the spray head assembly 76 and is atomised and enters the airstream within the air conditioning duct as a dry fog having a particulate size between 5 to 10 microns

that will allow vaporisation of the product within the air duct. The dry fog and/or vaporised tea tree oil is subsequently delivered to a room via room register 106.

The control means of the apparatus preferably are programmed into the printed circuit board of the main control unit or the injector control unit. In the embodiment shown in figures 1 to 9, the printed circuit board having the cycle times of nozzle operation is located in the injector control unit. The injector control unit display unit includes a level switch 90 to enable the appropriate cycle time or cycle level to be input. Three levels of treatment may be included (level 1, level 2 and level 3), with level 1 being for normal operation when microbiological levels are below 100 cfu per cubic metre. Level 2 is used for when microbiological levels are between 100 and 1,000 cfu per cubic metre or for high risk areas. Level 3 is used when microbiological levels of greater than 1,000 cfu per cubic metre are encountered and for initial treatment upon installation. The microbiological levels (in cfu per cubic metre) are determined by room air quality tests perfonned before installation of the apparatus and during lifetime service.

In other embodiments, the following levels of treatment may be used: Level 1-maintenance, low risk areas.

Level 2-treatment, medium risk areas and odours.

Level 3-used on initial installation for a wash through, high risk of microbial contaminants.

The test button 92 overrides the microprocessor to test operation of the ICU and spray nozzle Operation of the apparatus is simplified when the rate of delivery of the tea tree oil containing fluid during the injection cycle is kept at a constant level across all three levels, with the delivery time of each cycle increasing to account for increased dosages of tea tree oil containing fluid. However, it will also be appreciated that the present invention also encompasses a control system that has constant delivery cycle times but varies the rate at which tea tree oil is delivered during the injection part of each cycle.

When the control means indicates it is time to stop delivering the tea tree oil containing fluid to the duct, the control system triggers the three-way solenoid to close the nozzle pin 82, which stops the flow of tea tree oil containing fluid to the nozzle assembly. Because the nozzle may be required to operate as quickly as 200 milliseconds when the three-way solenoid is de-energised, the air remaining in the tube between the solenoid and the nozzle pin is expelled through a third port in the three-way solenoid to thereby ensure accurate dosages of fluid.

Location of the solenoids in the injector places the solenoids close to the atomiser, which increases response time.

It will also be appreciated that the invention also encompasses the use of a control means that can detect the level of the tea tree oil in the rooms to which the tea tree oil is being delivered and to initiate appropriate shutdown action if the tea tree oil levels reach a predetermined maximum.

The main control units incorporates a level switch located in the pressure vessel 10 and indicated as an LCD display. The display can provide information as to the level of the tea tree oil containing fluid in the pressure vessel 10, thereby indicating to users when top-up of the tea tree oil containing fluid is required. The system may also incorporate an alarm to warn when the tea tree oil containing fluid level is low. It may also encompass a back-to-base feature to indicate that the tea tree oil containing fluid level is low.

The present invention provides an apparatus and method that is suitable for delivering treatment fluids to spaces, such as air conditioning ducts or rooms. The apparatus utilises simple, off the shelf standard equipment. The apparatus has a relatively low manufacturing cost.

In preferred embodiments, the apparatus is conveniently provided as a modular unit including a main control unit and one or more injector control units. Installation of the apparatus is simple, requiring the injector control unit and its associated nozzle assemblies to be mounted to the wall of a duct, followed by simple interconnection between the injector control unit and the main control unit using tubing and electrical interconnections. The apparatus is easy to install and easy to use. Operation of the apparatus merely requires filling of the pressure vessel with the treatment fluid, selection of the appropriate treatment level and activation of the on/off switch.

Those skilled in the art will appreciate that the present invention may be susceptible to variations and modifications other than those specifically described. It is to be understood that the present invention encompasses all such variations and modifications that fall within its spirit and scope.