Abstract:
A method and apparatus for regulating an amount of ozone incident to an air stream of an air purifier. The air purifier has a number of ultra violet light lamps, a catalyst, a first sensor, a second sensor, a ventilating duct, an array of baffles and a fan. The first sensor and second sensor detect a first and a second level of contamination of the air stream and, in response thereto, the array of baffles increase or decrease the travel path of the air stream for exposure by the UV lamps. The UV lamps and catalyst also move with respect to each other for varying the amount of exposure of the UV lamps to the contaminated air stream to regulate the ozone incident on the air stream. The improved apparatus improves the efficiency by regulating the amount of ozone incident to an air stream for varying cooking loads.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application is claiming priority of U.S. Provisional Patent Application Serial No. 60/349,179 filed on Jan. 16, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to a ventilation method and system for kitchens using ultra violet tubes or lamps. More particularly, the present invention relates to an ultra violet light assembly having a mode for regulating an amount of ozone incident to an air stream.  
         BACKGROUND OF THE INVENTION  
         [0003]    Ventilation systems are known for removing contaminated air produced by a cooking appliance. The contaminated air has contaminants, such as smoke, grease, odors and other unwanted airborne substances. Ultra Violet (UV) light is known to disinfect contaminants within a liquid or gas that is exposed thereto, with one example being contaminated air. UV light wavelengths commonly used for purification are about 185 nanometers (nm) and about 254 nm.  
           [0004]    UV based air purification systems generally include a UV light source disposed to interact with a stream of contaminated air. UV light generally has a short wavelength. UV light in the C band has a wavelength in the range of about 180 nm to about 260 nm. The peak output of an ozone producing lamp is at a wavelength of about 253.7 nm. Generally, a drawback of UV lamps is that the UV lamps need time to stabilize and to operate at full output to assure germicidal properties.  
           [0005]    The number of fast food businesses and catering establishments has risen in recent years. Over the same time period there has been established more stringent air pollution and odor pollution requirements and reported nuisances have also risen from these establishments. Contaminants released from these cooking establishments, especially from deep fat frying, result in fatty deposits and unfavorable odor. Furthermore, the potential for fire hazard due to a build up of grease and oil deposits is great. Typically, restaurateurs require costly high-pressure washing and maintenance in order to minimize the risk of fire hazard. There is a need to avoid the risk of a fire hazard and to reduce the amount of contaminants in the air stream expelled from establishments using a ventilation system.  
           [0006]    Traditionally, commercial-catering establishments use mechanical filters to reduce contaminants. The use of High Efficiency Particulate Arresting (HEPA) filters to filter and collect particulate matter is well known in the art. Filters are not usually effective for ultra fine particles such as expected in food due to rapid clogging rates of the filter that also may result in a fire hazard. Also filters tend to collect grease and fat thereby creating fire hazards. Due to the nature of filter materials, there are also inherent limitations in temperature and humidity working conditions.  
           [0007]    Another solution in the art has been catalytic oxidation of emissions to CO 2  and water. Oxidation of gaseous contaminants has the advantage that wastes are minimized. Catalytic oxidation requires electricity or high temperature ranges (250-350° C.) for effectiveness. The catalysts also require a steady load of gaseous contaminants and a stable flow for the input in order to be effective. This method will not be very effective in commercial kitchens where the load of gaseous contaminants is not steady due to batch cooking and the temperatures are usually only up to 200° C.  
           [0008]    Another solution in the art has been the use of activated carbon. Although the solution is effective there is a maintenance cost as absorption materials need to be changed regularly. Typically, this technology is based on the absorption properties of porous carbon material, which is used to arrest pollutants. The carbon material becomes polluted with use and must be replaced with new materials. A drawback is that the level of grease and fat generated that will be deposited on the materials. Increased deposits lead to increased maintenance costs and labor intensive requirements. It is estimated that the cost of this method in this application will be 40% more than that of filters.  
           [0009]    Another solution in the art is the combustion of gaseous materials. Combustion is only suitable for a large unit where there is a constant and a steady supply of gaseous contaminants to burn. This will not be particularly suitable for commercial catering applications as it is hazardous, cumbersome and requires a high level of maintenance. It also poses a risk of a fire hazard that the food establishment seeks to minimize. This method also generates its own pungent odor.  
           [0010]    In commercial catering, the mechanism of operation is based on a combination of sterilization and destruction of organic matter by ultraviolet radiation at certain wavelengths using ozone. At these wavelengths the ability of ozone to readily oxidize other elements reduces deposition of fat and grease in the ductwork. The approach has had success in a laboratory under a controlled environment, but the approach enjoyed only limited success in practice. This is attributed to an unstable flow in the application environment, where the gaseous contaminants vary in such a dynamic way that the prior art is not capable of responding fast enough. A barrier to effective deployment of UV and ozone against odor and pollution abatement is an inability to control the UV and ozone generation mechanisms. This prevents a rapid response to variable and dynamic loads of pollution that is typical of commercial batch catering environment.  
           [0011]    Typically, restaurants and catering operations do not produce uniform amounts of contaminants throughout the course of a day. The amount of gaseous contaminants depends upon the food type, cooking process and the cooking load. At peak times of the day, optimum amounts of UV and ozone are desired. At the lowest point of activity, when there are reduced cooking loads, a minimum amount of UV and ozone is desired to avoid excess ozone production and the attendant ozone odor. Therefore, while the mechanism of odor control and the effect on gaseous contaminants is effective, the use of UV lamps is very complex and difficult to control, hence, the difficulties associated with the implementation in practice.  
           [0012]    Ozone production incident to an air stream is effective on both gaseous contaminants and other biological contaminants that propagate odors. However, for this method to be used for pollution abatement, there is a need for it to be combined with an effective apparatus for regulating the UV and ozone incident upon an air stream that is disposed in the duct.  
           [0013]    There is a need for an improved air purifier that dynamically regulates the concentration of ozone incident to an air stream and/or the time of such incidence.  
           [0014]    There is a need for an improved air purifier that continually shortens response time for ozone to be incident to an air stream.  
           [0015]    There is also a need for a safe, dynamic response to emission input loads by a multivariable controlled, integrated pollution and odor abatement system.  
           [0016]    There is also a need for a system capable of removing solid and liquid matter as well as neutralizing gaseous contaminants and odors while preventing the build up of fat and grease that are potential fire hazard.  
         SUMMARY OF THE INVENTION  
         [0017]    According to a first aspect of the present invention, an apparatus is provided that has a ultraviolet light source that produces ozone incident upon an air stream in a ventilating duct. The apparatus also has a regulator that regulates the ozone incident upon the air stream. The regulator has a modulating structure that modulates the ozone and also has a control circuit. The control circuit responds to signals corresponding to a level of contamination or a level of ozone of the air stream to control the modulating structure. The modulating structure may be a baffle, a catalyst, an intermediate member, and any combination thereof.  
           [0018]    According to still another preferred embodiment of the present invention, the regulator has at least one sensor disposed in the ventilating duct, a microprocessor, and the modulating structure. The microprocessor responds to signals provided by at least one sensor to actuate the modulating structure in response to the contaminants. The modulating structure is actuated between a maximum ozone producing position corresponding to a maximum amount of ozone incident on the air stream and a minimum ozone producing position corresponding to a minimum amount of ozone incident on the air stream.  
           [0019]    According to still yet another preferred embodiment of the present invention, the microprocessor controls an actuator for configuring the baffle into a first travel path corresponding to a maximum amount of ozone incident on the air stream and into a second travel path. The second travel path corresponds to a minimum amount of ozone on the air stream. The first travel path has a distance greater than the second travel path.  
           [0020]    According to still another preferred embodiment of the present invention, the apparatus has a vibrator for vibrating a first and second electrostatic precipitators. This removes contamination and particulate matter from the first and second electrostatic precipitators.  
           [0021]    According to another feature of the present invention, there is provided a method of purifying an air stream comprising passing the air stream by an ultraviolet light source sufficient to create ozone in the air stream and regulating an amount of said ozone incident upon the air stream.  
           [0022]    According to another feature of the present invention, there is provided a ventilation system having a ventilation housing which comprises a ventilation duct. The ventilation system also has an ozone generator disposed within the ventilation duct, a vacuum source capable of drawing an air stream to be treated through the ventilation duct, and a regulator. The regulator is capable of increasing or decreasing an amount of ozone within the air stream as the air stream traverses through the ventilation duct. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    Other and further objects, advantages and features of the present invention will be understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference characters denote like elements of structure and:  
         [0024]    [0024]FIG. 1 is a block diagram of the air purifier of the present invention.  
         [0025]    [0025]FIG. 2 is a cross-sectional view of the air purifier of the present invention with an array of UV lamps and an array of baffles in a closed position.  
         [0026]    [0026]FIG. 3 is a partial cross-sectional view of the air purifier of the present invention with the array of baffles in an opened position.  
         [0027]    [0027]FIG. 4 is a cross-sectional view of another embodiment of the air purifier of the present invention with an array of UV lamps having a shield.  
         [0028]    [0028]FIG. 5 is a cross-sectional view of still another embodiment of the air purifier of the present invention having an exemplary catalyst.  
         [0029]    [0029]FIG. 6 is a cross-sectional view of still yet another embodiment of the air purifier of the present invention having an exemplary catalyst and an intermediate member disposed between the array of the UV lamps and the exemplary catalyst.  
         [0030]    [0030]FIG. 7 is a cross-sectional view of still another further embodiment of the air purifier of the present invention having an exemplary catalyst and an intermediate member having one or more apertures disposed between the UV lamps and the exemplary catalyst. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]    With reference to FIG. 1, there is provided a block diagram of an air purifier  15  of the present invention. Air purifier  15  may be disposed in a conventional commercial or residential ventilation duct  10  adjacent to a cooking source (not shown) as is known in the art. An air stream (shown by the arrow in FIG. 1) passes through the ventilating duct  10 . Air purifier  15  includes UV lamps  25  that produce ozone to treat contaminants in the air stream and a regulator  12  that regulates the ozone incident to the air stream.  
         [0032]    Regulator  12  is at least partially disposed in ventilation duct  10 . Regulator  12  has a modulating structure  30 , an actuator  40  preferably disposed outside of the ventilating duct  10 , a first sensor  60 , a second sensor  65  and a control circuit  90 . The modulating structure  30  modulates the ozone incident upon the air stream and is controlled by control circuit  90 . The control circuit  90  responds to signals provided by the first sensor  60  and the second sensor  65  corresponding to a level of contamination or ozone in the air stream, and controls the modulating structure  30  accordingly by actuator  40 . Control circuit  90  preferably is a microprocessor, more preferably a DSP type processor or other suitable processor. Control circuit  90  monitors the output of the first sensor  60  and second sensor  65  to modulate the modulating structure  30  by actuator  40 .  
         [0033]    With reference to FIG. 2, UV lamps  25  comprise an array of ozone producing UV lamps  25  disposed in ventilation duct  25 . Preferably, the UV lamps  25  are ultra violet light tubes that emit energetic photons and emit radiation having a wavelength less than about 200 nm. In another embodiment of the present invention, the UV lamps  25  emit radiation having a wavelength of about 185 nm wavelength. In another preferred embodiment, the UV lamps  25  have a wavelength of about 185 to 254 nm. Modulating structure  30  comprises an array of baffles  30 . In addition, the ventilating duct  10  also has a fan  35 , actuator  40 , a removable metal pre-filter or coalescer  45 , a plurality of first stage electrostatic precipitators  50  and a plurality of second stage electrostatic precipitators  55 . Disposed at an inlet of the ventilation duct  10  is first sensor  60 . Disposed near or at the outlet of the ventilation duct  10  is second sensor  65 . The ventilation duct  10  also has a particulate collecting tray  70 . Control circuit  90  controls the one or more operations of the UV lamps  25 , the actuator  40  and any other operative functions is disposed at a suitable location located near the ventilation duct  10 .  
         [0034]    Control circuit  90  is also operatively connected to the actuator  40 , UV lamps  25 , first sensor  60  and second sensor  65 , a fan  35  and a power source (not shown). One aspect of UV lamps  25  is that they emit photons in a wavelength range of about 185 nm. The photons emitted from the UV lamps  25  are sufficient to produce mono-atomic oxygen in a contaminated air stream emitted from the cooking source (not shown) in spaced relation to the UV lamps  25 . UV lamps  25  are disposed substantially perpendicular to the flow of contaminated air passing through ventilating duct  10 . An aspect of the UV lamps  25  is the rapid response of regulating the amount of ozone incident to an air stream.  
         [0035]    UV lamps  25  are disposed in ventilating duct  10  in a series of rows, in a series of columns or in any suitable arrangement for emitting a germicidal dosage of ultra violet light in the contaminated air stream in the ventilating duct  10 . Baffles  30  are disposed between the rows of the UV lamps  25 . Baffles  30  are vertically disposed in the ventilating duct  10  in a suitable arrangement for selectively altering the flow of the contaminated air stream between the rows of the UV lamps  25 . Baffles  30  may increase a travel path or pressure of the contaminated air stream around the UV lamps  25 .  
         [0036]    In one embodiment, the baffles  30  may have an opened position and a closed position. In the opened position shown in FIG. 3, the contaminated air stream may have a relatively shortened travel path, whereas in a closed position shown in FIG. 2, the baffles may travel in a relatively longer travel path around the UV lamps  25  for increased exposure to the UV light. The array of baffles  30  selectively open or close by being actuated by the actuator  40 .  
         [0037]    Referring again to FIGS. 2 and 3, as mentioned a contaminated air stream passes through ventilating duct  10  in the direction toward fan  35 . In an exemplary embodiment of the present invention, when engaging in a light cooking load there is a reduced amount of oil and grease in the contaminated air stream. Here, baffles  30  are disposed in the open position as shown in FIG. 3. This opened position allows the contaminated air stream to pass through a relatively short travel or relatively lower pressure path in the ventilating duct  10 .  
         [0038]    However, during a high cooking load, the contaminated air stream has an increased amount of oil, grease and contaminants. A first sensor  60  in response thereto communicates a first signal to actuator  40  for actuating one or more of the array of baffles  30  to the closed position. The closed position increases the travel path or increases the pressure of the contaminated air stream for increasing the exposure time of the UV lamps  25  to the contaminated air stream as shown in FIG. 2.  
         [0039]    First sensor  60  may be a flame ionization sensor, a photo-ionization sensor, an infrared sensor, a gas chromatography, mass spectrometry sensor, a bulk wave acoustic sensor, a surface wave acoustic sensor, a metal oxide based sensor or any other sensor known in the art. First sensor  60  communicates a first signal that corresponds to either a high cooking load or a second signal corresponding to a low cooking load to control circuit  90 .  
         [0040]    In an alternative embodiment, second sensor  65  also may communicate either a first signal that corresponds to either a high cooking load or a second signal corresponding to a low cooking load to control circuit  90 . In still another embodiment, second sensor  65  may either communicate a first signal that corresponds to either a high concentration of ozone or a second signal corresponding to a low concentration of ozone to control circuit  90  for regulating ozone. Referring to FIGS. 2 and 3, the second sensor  65  preferably measures the amount of ozone at the end opposite the cooking source that is disposed beneath the ventilation duct  10  and the first sensor  60  preferably measure the amount of contaminants. Here, first sensor  60  communicates a first signal and second sensor  65  communicates a second signal to control circuit  90  for controlling UV lamps  25  and/or baffles  30 .  
         [0041]    An example of first sensor  60  and second sensor  65  may be a surface acoustic wave chemical sensor in a matrix with a pressure transducer (not shown). Pressure transducer senses the level of loading while the matrix of the acoustic wave chemical sensor senses a variety of polar (such as alcohol esters and ketones) and non-polar oxygenated nitrogenated and chlorinated compounds. In one exemplary embodiment of the present invention, first sensor  60  and second sensor  65  may be a polar compound sensor that senses largely polar organic compounds on the input while sensing oxygenated matter or ozone at the output.  
         [0042]    An aspect of first sensor  60  and second sensor  65  is that the sensors are suitable for measurement, preferably in milliseconds. Another aspect of first sensor  60  and second sensor  65  is that first sensor  60  and second sensor  65  are accurate without regular maintenance and are easily integrated with the control circuit  90  for a cost-effective installation.  
         [0043]    In one exemplary embodiment of the present invention, the array of UV lamps  25  synchronized by a linkage will be used in the ventilation duct  10  for regulating dynamically the ozone concentration in the system based on a feedback loop in control circuit  90 .  
         [0044]    Since first sensor  60  and second sensor  65  can be affected by the continuous presence of dust, a suitable shielding system (not shown) is provided for preferably keeping out dust, grease and other contaminants. First sensor  60  is placed behind the first stage electrostatic precipitators  50  to protect second sensor  65  from dust and prevent an erroneous reading of the level of gaseous contaminants.  
         [0045]    In response to a high cooking load, actuator  40  may shift baffles  30  from a closed position to an opened position to decrease the travel path of the air stream, thereby decreasing the amount of ozone incident to the air stream. In another embodiment, actuator  40  may completely open only some of the baffles  30  while not opening the remainder. In still another embodiment of the present invention, actuator  40  may only slightly open or may only slightly close the baffles  30  for modulating the amount of ozone incident to the air stream.  
         [0046]    In an embodiment of the present invention, actuator  40  directs the air stream to a first travel path, a second travel path or any combinations thereof. In response to a low cooking load, actuator  40  shifts the baffles  30  from a closed position to an opened position, thereby decreasing the amount of ozone incident to the air stream.  
         [0047]    Actuator  40  comprises a motor, (not shown) hydraulic jack or manual actuator to actuate one or more baffles  30  from the open position to the closed position. In this embodiment, baffles  30  may increase the air pressure of the contaminated air stream that is passing through the ventilating duct  10 . Air pressure is increased and contaminated air is forced to circulate around baffles  30  and in proximity to UV lamps  25  for increasing the exposure time of the UV lamps  25  to the contaminated air stream.  
         [0048]    While the presence of ozone can convert gaseous contaminants into harmless by-products and sterilize and destroy bacterial causing odor, the abatement of particulate matters needs to be addressed. First and second electrostatic precipitators  55  and  60  preferably operate using a programmable switch mode power supply (not shown). The programmable switch mode power supply enables the user to use a vibrator (not shown) to vibrate a pole of the first and second electrostatic precipitators  55  and  60  so that all the contaminants can drop on to a collection tray  70  for disposal as a dry waste.  
         [0049]    Actuator  40  is any suitable mechanical actuating mechanism, or other such suitable automatic or manual mechanical device, such as one connected to, for example a hydraulic jack (not shown) by a sensor link for actuating the array of baffles  30  in the contaminated air stream. Actuator  40  may have a series of gears (not shown) operatively connected to a motor (not shown) and may be bolted or fastened to ventilating duct  10  on an interior side of the ventilating duct. Baffles  30  and UV lamps  25  may be fastened to ventilating duct  10  by any suitable fastener, presently known or known in the future.  
         [0050]    The present invention regulates the ozone incident upon an air stream. The regulator  12  has a modulating structure  30  that modulates the ozone incident on the air stream. The regulator  12  has control circuit  90  and the actuator  40 . The control circuit  90  responds to signals corresponding to a level of contamination of the air stream to control and impart a modulating motion to the modulating structure.  
         [0051]    An exemplary aspect of the present invention is the ability to regulate the ultra violet light emitted by UV lamps  25  thereby modulating an amount of ozone that is incident to the contaminated air stream. By modulating the amount of ozone, a user optimally provides for a desired amount of germicidal properties to the contaminated air stream while simultaneously minimizing any possible ozone odor depending upon an amount of cooking emissions released from the cooking source.  
         [0052]    In one embodiment of the present invention the amount of ozone is regulated by modulating current, voltage or the power to the UV lamps  25  based upon an output of the first sensor  60 . As mentioned, first sensor  60  is disposed at an inlet of the ventilation duct  10  or any other suitable location for obtaining a reliable reading of an amount of effluent in the air stream. First sensor  60  measures one or more amounts of effluent in the contaminated air stream and outputs a first signal to control circuit  90 . Based upon first signal of first sensor  60  communicated to control circuit  90 , control circuit  90  may selectively modulate the UV lamps  25  by interrupting, increasing or decreasing the power supply, current or voltage to the UV lamps  25 .  
         [0053]    Control circuit  90  may also selectively modulate the UV lamps  25  by switching off one or more UV lamps  25  disposed in the array in a step by step fashion. In this embodiment, a desired number of UV lamps  25  are in the off position, while the remainder of the UV lamps  25  in the ventilating duct  10  are in the on position and any combinations thereof.  
         [0054]    In another embodiment of modulating the amount of ozone incident to the contaminated air stream, first sensor  60  measures an amount of effluent in the contaminated air stream and outputs a first signal to control circuit  90 . Control circuit  90  in response to the first signal regulates the velocity of the contaminated air stream travelling through the ventilating duct  10  in spaced relation to the UV lamps  25 , for example, increasing or decreasing the speed of fan  35 .  
         [0055]    Preferably, first sensor  60  communicates a first signal corresponding to a high cooking load to control circuit  90 . Control circuit  90  responds thereto by controlling fan  35  to decrease the velocity of the contaminated air stream over the UV lamps  25  so as to increase the exposure time and increase the amount of ozone incident to the contaminated air stream. Alternatively, in the instance of a low cooking load, first sensor  60  communicates a second signal corresponding to a low cooking load to control circuit  90 . Control circuit  90  in response thereto increases the velocity of the contaminated air stream over the UV lamps  25  for decreasing exposure time and decreasing the amount of ozone incident to the contaminated air stream.  
         [0056]    With reference to FIG. 4, in another embodiment of modulating the amount of ozone incident to the contaminated air stream a shield  112  is provided. Shield  112  may be any suitable shape or size for shielding the UV lamps from any cooling effect of the contaminated air stream.  
         [0057]    Shield  112  may be U shaped, T shaped, V shaped, W shaped, arcuately shaped, parabolic, oblong or any other shape or size that can be disposed on the upstream side of UV lamps  25  maintaining a temperature of the UV lamps. Shield  112  preferably prevents the UV lamps  25  from cooling. Shield  112  shields air flow in front of the UV lamps  25 , to prevent the contaminated air stream from cooling the UV lamps  25  thereby maintaining an intensity of the UV lamps and increasing the amount of ozone incident to the contaminated air stream.  
         [0058]    With reference to FIG. 5, another embodiment of regulating the amount of ozone incident to the contaminated air stream provides a catalyst  100  that is located at a predetermined distance from the UV lamps  25  so as to intensify the reaction of UV light illuminated on the passing air stream. In one embodiment, at least one or the UV lamps  25  may have a catalyst  100  operatively connected to the actuator  40 . Actuator  40  may further comprises a first gear, a second gear, a motor and an output shaft for moving the catalyst  100  or the UV lamps  25  relative to the other. As mentioned, in another embodiment, actuator  40  is a jack or motor preferably having an input and output coil (not shown) that is electrically connected to power source (not shown) is used for actuating the catalyst  100  or the UV lamps  25  relative to the other.  
         [0059]    Catalyst  100  may be a substantially cylindrical structure, a semi-spherical structure, a polyhedron, a rectangular member, a pyramid shaped member, an oblong structure, a rectangular structure, a spherical structure or a walled surface in an interior of the ventilating duct  10  as illustrated in FIG. 5. Catalyst  100  may also be disposed on at least a portion of the shield  112  or may be any shape for effectively reflecting an amount of germicidal ultra-violet light from catalyst to create ozone incident to a contaminated air stream.  
         [0060]    Catalyst  100  may also be disposed more distant from the UV lamps  25  one or more walls, on one or more baffles, housing, floors, or structures in the ventilation duct  10 . Alternatively, catalyst  100  may also be a suitably shaped member disposed in concentric relation over UV lamps  25 .  
         [0061]    It is not practical to constantly switch on and off UV lamps  25  as the life of the UV lamps will be significantly reduced. This will result in increased maintenance costs to the food establishment resulting in constant replacement of the UV lamps  25  and service costs associated with the replacement. Therefore, in this embodiment, it is preferable that UV lamps  25  be left in the illuminated position to obviate the start up time to reach optimum performance. It has been shown that the ratings of the UV lamps  25  indicate that the ozone generation is at a concentration of approximately 0.9 mg/m 3  based on the air volume of the ventilation duct  10  but the maximum ozone generation preferably is 0.16-0.18 mg/m 3 .  
         [0062]    Catalyst  100  is any suitable material for reflecting germicidal UV light and preferably is a titanium dioxide material, a material coated with titanium oxide or any other reflective material or reflective coating. Preferably, as shown in FIG. 5, the UV lamps  25  are exposed to the coated titanium dioxide material in a first position for a maximum ozone generation. The UV lamps are moved away from the catalyst  100  to at least a second position for minimum ozone generation. When UV lamps  25  are spaced closer to catalyst  100 , an increased amount of UV light is exposed to the contaminated air stream and, accordingly, an increased amount of ozone is incident to the contaminated air stream. When the sensors indicate that less ozone is needed, UV lamps  25  will be spaced further from the catalyst  100 .  
         [0063]    Referring to FIG. 6, another embodiment of the present invention regulates the amount of ozone incident to an air stream by providing UV lamps  25  with an intermediate member  120 . Intermediate member  120  is any non-reflective solid material having a predetermined surface area suitable for blocking or otherwise covering catalyst  100  or covering the UV lamps  25 . When UV lamps  25  are blocked from the catalyst  100  by the non-reflective intermediate member  120 , a decreased amount of UV light is exposed to the contaminated air stream relative to the instance when UV lamp  25  is exposed to the catalyst  100 . Accordingly, a relatively decreased amount of ozone is produced incident to the contaminated air stream. This preferred embodiment results in less ozone incident to the contaminated air stream.  
         [0064]    An exemplary aspect of the present invention, is that in one preferred embodiment, intermediate member  120  is operatively connected to actuator  40 . In this manner, actuator  40  rotates catalyst  100  closer to, or farther away from the UV lamps  25 . Actuator  40  may also rotate intermediate member  120  to block the catalyst  100  from UV lamps  25 .  
         [0065]    Another embodiment of the present invention shown as FIG. 7 provides intermediate member  120  having one or more apertures  150 . The apertures  150  allow intermediate member  120  to selectively expose or cover the catalyst  100  with minimum rotation of intermediate member  120 . This selective blocking maintains or decreases the exposure of UV lamps  25  to catalyst  100  and the contaminated air stream, thereby allowing a user to control the intensity of the UV lamps  25  without completely terminating the illumination of the UV lamps  25 . Apertures  150  are disposed on intermediate member  120  in a suitable pattern and may have any shape or size. Intermediate member  120  selectively shields or otherwise blocks UV lamps  25  from catalyst  100  by a minimal rotation of the intermediate member  120  to vary exposure of the UV lamp  25  to catalyst  100  and the contaminated air stream.  
         [0066]    In another preferred embodiment of the present invention, (not shown) one or more UV lamps  25  are moved away from catalyst  100  by actuator  40  thereby reducing the amount of UV light exposed to the contaminated air stream resulting in less ozone incident to the contaminated air stream. Similarly, UV lamps  25  are moved toward a stationary catalyst  100  by actuator  40 . Catalyst  100  may also be formed as a circular shaped member with a diameter sufficient to envelop multiple UV lamps  25 .  
         [0067]    Ventilating duct  10  may be any suitable ventilating duct known or presently known in the future. Excess contaminants, such as grease, flow down removable metal pre-filter  45  and collect in gutter (not shown) for subsequent removal by service personnel and to minimize fire hazard. It should be apparent to one skilled in the art, that the present invention may be used either in commercial or residential ventilating ducts or any other air purifier utilizing UV lamps.  
         [0068]    Contaminated air flows from a cooking source (not shown) through a removable pre-filter  45 . Removable pre-filter  45  prevents oil and grease droplets to pass through pre-filter  45  and instead causes oil and grease to flow opposite the UV lamps  25  to maintain the operational performance the UV lamps and for safety reasons.  
         [0069]    The present invention having been thus described with particular reference to the preferred forms thereof, it will be obvious that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as defined in the appended claims.