Abstract:
A cleaning apparatus comprising a first fluid delivery system configured to eject a first fluid through a first nozzle toward a surface to be cleaned; a second fluid delivery system configures to eject a second fluid through a second nozzle toward the surface to be cleaned, wherein the second fluid comprises a compressed gas at a pressure greater than 345 kilopascals (50 pounds per square inch); a housing configured to partially surround and mount the first and second nozzles; a connector configured to couple the first fluid delivery system to a first fluid source; and a connector configured to couple the second fluid delivery system to a second fluid source.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application is a divisional of U.S. application Ser. No. 14/550,066 filed Nov. 21, 2014 for “Coil Cleaning System” by Scott P. Burfeind. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates to cleaning equipment, and more specifically, to a cleaning apparatus for heat exchanging coils. 
         [0003]    Heat exchanging coils such air conditioning/refrigeration coils, process fluid coolers, hydraulic fluid coolers, and similar mechanical structures require regular cleaning to maintain efficient heat transfer. Such heat exchangers generally comprise a tube containing a refrigerant surrounded by a plurality of thin metal plates or fins. A fan drives ambient air through the fins and around the tubes to draw heat from the refrigerant. The fins serve to increase the surface area of heat transfer and, therefore, are generally stacked close together (passageways may be less than 2.5 millimeters wide). While such configuration improves the heat exchanging capacity, efficiency declines as the fins clog with oils, dust, pollen, plant seeds, process by-products, and other contaminants present in the ambient air. 
         [0004]    Conventional coil cleaning methods include the use of chemical cleaners, brushes, high pressure water delivered from pressure washers or backpack sprayers, and compressed air. Each has advantages and disadvantages. Brushes and chemical cleaners may effectively loosen contaminants, but are ineffective at removing them from the coil. Water and water-based chemical spraying systems may remove oils that have caked onto the coil, but due to surface tension or friction of water, high pressure is required to force the liquid fluid and contaminants through the narrow passageways of the coil. Additionally, the large volume of water required to clean the coil can damage other components of the system. High pressure air effectively carries contaminants such as dust and debris out of the coil, but may not have enough force to loosen and remove hardened buildup or remove the oils which, if left in place, attract additional contaminants. 
         [0005]    Both high pressure water and compressed air systems generally require small nozzles or orifices to deliver a high pressure stream of fluid. The small nozzles limit the effective cleaning area, which increases the amount of time it takes to clean the coil and the amount of cleaning fluid required. Additionally, the pressure required to remove contaminants from the coil is sufficient to bend, fold, or damage the thin metal fins. When fins are bent such that they abut adjacent fins or reduce the space between adjacent fins, heat exchanging efficiency is lost and the narrower passageways become more difficult to clean. Operators must use care in spraying the coil to avoid such damage. 
         [0006]    In addition to conventional coil cleaning systems, the prior art discloses a low-pressure air coil cleaning system (U.S. Pat. No. 7,132,017), such as a leaf blower, that may be equipped with a cleaning fluid injector to create a “cleaning fluid mist.” The air pressure of the prior art system is too low to damage coil fins, but also too low to drive a cleaning fluid into the narrow coil passageways and force the cleaning fluid and contaminants out of the coil. 
         [0007]    There is a need for an improved coil cleaning system that is capable of removing all types of contaminants from the narrow coil passageways in a single application, while also reducing the risk of damaging the coil fins and reducing the labor time needed. 
       SUMMARY 
       [0008]    A cleaning apparatus comprising a first fluid delivery system configured to eject a first fluid through a first nozzle toward a surface to be cleaned; a second fluid delivery system configures to eject a second fluid through a second nozzle toward the surface to be cleaned, wherein the second fluid comprises a compressed gas at a pressure greater than 345 kilopascals (50 pounds per square inch); a housing configured to partially surround and mount the first and second nozzles; a connector configured to couple the first fluid delivery system to a first fluid source; and a connector configured to couple the second fluid delivery system to a second fluid source. 
         [0009]    Another embodiment is a cleaning apparatus configured to clean a coil of a heat exchanger, comprising: a spray nozzle configured to deliver a first fluid; a discharge channel with a plurality of apertures configured to deliver a second fluid; a housing configured to mount and partially surround the spray nozzle and the discharge channel to allow delivery of the first and second fluids to the coil, wherein the discharge channel is configured to deliver the second fluid into a discharge stream of the first fluid; a first connector configured to couple the spray nozzle to a first fluid source; a second connector configured to couple the discharge channel to a second fluid source; and a valve to adjust at least one of a first or second fluid flow rate or pattern of discharge. 
         [0010]    A method for cleaning a heat exchanger coil comprising: connecting a first fluid delivery system to a first fluid source, wherein the first fluid comprises a cleaning agent selected from the group consisting of water, solvents, detergents, and a combination thereof; connecting a second fluid delivery system to a second fluid source, wherein the second fluid comprises a compressed gas; delivering a first fluid through a first nozzle of the first fluid delivery system toward the coil in a fluid stream, wherein the first nozzle is mounted in the cleaning apparatus housing; delivering a second fluid through a second nozzle of the second fluid delivery system into the first fluid stream, creating a second fluid stream, wherein the second nozzle is mounted in the cleaning apparatus housing; adjusting at least one of the rate and pattern of flow or at least one of the first and second fluid delivery systems with valves connected to the cleaning apparatus to create a fluid mixture capable of removing particulate matter from the heat exchanging coil without bending coil fins; and positioning the cleaning apparatus housing within two feet of the coil. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a coil cleaning apparatus and a coil. 
           [0012]      FIG. 2  is a perspective view of the coil cleaning apparatus. 
           [0013]      FIG. 3  is a perspective view of an alternate embodiment of the coil cleaning apparatus. 
           [0014]      FIG. 4  is a front elevation view of the coil cleaning apparatus. 
           [0015]      FIG. 5  is a front elevation view of and alternate embodiment of the coil cleaning apparatus. 
           [0016]      FIG. 6  is a side view of the coil cleaning apparatus. 
           [0017]      FIG. 7  is a side view of an alternate embodiment of the coil cleaning apparatus. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The coil cleaning apparatus  10  combines two methods of coil cleaning—gaseous and liquid, such as compressed air and water—by directing a high-pressure stream of compressed gas into a lower-pressure liquid stream. The high-pressure gaseous stream disperses the liquid stream into fine droplets capable of entering the confined spaces of the coil and forces the droplets and the contaminants they entrain through the narrow passageways and out of the coil  50  without damaging fragile coil fins. The simultaneous application of high-pressure gas and liquid fluid cleaning methods results in fewer labor hours required to clean the coil and a more thorough cleaning than can be achieved using one method alone or the low-pressure mixed stream cleaning system disclosed in the prior art. Additionally, a reduced run time of equipment saves energy, which in turn extends the life cycle of the heat transfer equipment; and use of a compressed gas to more evenly disperse a liquid cleaning fluid reduces the amount of water required when compared to water-based single fluid cleaning systems, such as garden hoses and pressure washers. 
         [0019]    The coil cleaning apparatus  10  simultaneously discharges gaseous and liquid fluids to create a high-pressure, high-velocity dense mist comprising approximately  70  percent gas and  30  percent liquid fluid. The prior art discloses a “cleaning fluid mist” created by mixing a liquid cleaning fluid with a low-pressure stream of air (U.S. Pat. No. 7,132,017). A fluid mist is ineffective as a cleaning agent unless it can be delivered to the coil in droplets that are of sufficiently small size to reach the confined spaces within the coil and with sufficient pressure to dislodge and carry away oils, dirt, debris, and other contaminants. By combining a liquid fluid with a high-pressure gas, the coil cleaning apparatus creates a high-pressure, high-velocity dense mist capable of removing contaminants from the narrow passageways of the coil. The low-pressure air stream of the prior art may disperse a portion of the liquid cleaning fluid into a fluid mist, but it would not have sufficient force to drive the liquid cleaning fluid and hardened buildup through the narrow passageways of the coil. 
         [0020]      FIGS. 1-3  illustrate various views of a coil cleaning apparatus  10  that combines gaseous and liquid coil cleaning methods to effectively remove contaminants from a heat exchanging coil without damaging coil fins and while saving time and water. 
         [0021]      FIG. 1  shows a perspective view of the coil cleaning apparatus  10  and a coil  50 . The coil cleaning apparatus  10  includes a housing  12  that serves to fixedly mount a first and second fluid delivery system  14 ,  16  into a single structural unit and in a configuration that allows the second fluid, typically gaseous, to disperse and force the first fluid, typically liquid, through the coil  50 . The housing  12  partially surrounds the discharge ends of the first and second fluid delivery systems  14 ,  16 , opening toward the coil  50 . The housing  12  is constructed from a rigid or semi-rigid material, such as plastic. The housing  12  may serve to define the area to be cleaned as the housing  12  is positioned close to the coil during operation—generally within 1 to 5 centimeters. 
         [0022]    In one embodiment, the housing  12  is a rectangular box open on one side. The open side of the housing  12  extends slightly beyond a nozzle  20  on the discharge end of the second fluid delivery system  16  to prevent the nozzle  20  from contacting the coil  50 . It will be understood by those skilled in the art that the shape of the housing  12  can be modified to accommodate variations in fluid delivery systems and desired fluid discharge patterns. The liquid fluid is projected outward from the coil cleaning apparatus  10  to cover the coil  50  evenly. The nozzle  20  of the second fluid delivery system  16  is positioned near the bottom front of the housing  12  and emits a compressed gas, which forces the liquid fluid of the first fluid delivery system through the narrow passageways of the coil  50  and out of the coil  50 . 
         [0023]    The first fluid delivery system  14  is mounted through the back wall of the housing  12  and the second fluid delivery system  16  is mounted through the top of the housing  12 . The first fluid delivery system  14  may comprise a nozzle (not pictured), which is mounted through the back wall of the housing  12 , and a handle  18 , which remains outside of the housing  12 . The second fluid delivery system  16  is mounted through the top of the housing  12  so as to not obstruct the use of the handle  18  of the first delivery system  14 . The second fluid delivery system  16  includes an elbow connector  18  to minimize the vertical dimension of the coil cleaning apparatus  10 . Both first and second fluid delivery systems  14 ,  16  may also be connected to tubes, hoses, valves, and similar fluid delivery structures. Connections may be of a permanent type, such as PVC pipe and glue, or detachable. Detachable connectors may include adjustable hose clamps, threaded connectors, quick couplers, and similar connection mechanisms. Valves  34 ,  44  may be present to control the rate of delivery of the fluids through the delivery systems, or to entirely stop the delivery of one or both fluids. 
         [0024]    The first and second fluid delivery systems are connected to a first  17  and second fluid source  19 , respectively. The first fluid is typically a liquid, which may include water or a solution of water and cleaning agents, such as solvents and detergents. In one embodiment, the first fluid delivery system is connected to a garden hose. In an alternate embodiment, the first fluid delivery system is connected to a system configured to deliver both water and a cleaning solution. 
         [0025]    The second fluid is typically gaseous. In one embodiment, the second fluid delivery system  16  is connected to an air compressor through a quick coupler. In an alternate embodiment, the second fluid delivery system is connected to a source of compressed gas, such as a carbon dioxide tank or compressed gas generating system. 
         [0026]    The coil cleaning apparatus  10 , as disclosed, utilizes approximately 70 percent compressed gaseous fluid and 30 percent liquid fluid. The high-pressure gas disperses the liquid fluid into fine droplets capable of entering confined spaces within the coil and forces the droplets and the contaminants they entrain through and out of the coil  50 . While the 70 percent gaseous fluid, 30 percent liquid fluid combination is capable of removing the hardened buildup in most heat exchanger coils, various combinations may be employed to achieve acceptable results. In general, the optimal percentage of water ranges from 15 to 35 percent, whereas, the optimal percentage of gas ranges from 65 to 85 percent. The valves  34 ,  44  incorporated into the coil cleaning apparatus  10  allow the operator to adjust the ratio of gaseous fluid flow to liquid fluid flow as required for optimal cleaning of the heat exchanger coil  50 . 
         [0027]    The coil cleaning apparatus  10  may be hand-held or attached to an extension pole  13  for improved reach or mechanical control. The extension pole  13  may be detachably fixed to the housing  12  with a connector  31 . The coil cleaning apparatus  10  is designed to be operated in close proximity to the coil  50 . In one embodiment, the coil cleaning apparatus  10  is operated at a distance of approximately 1 to 5 centimeters away from the coil  50 . This distance is determined based on characteristics of the fluid discharge, such as volume, flow, and pressure. In one embodiment, the gaseous and liquid fluid mixture is discharged in a rectangular pattern that covers approximately 75 square centimeters, which facilitates an even application and thorough cleaning in the rectangular pattern area. As the coil cleaning apparatus  10  is moved adjacent the coil  50 , the hardened buildup is removed in the area of the rectangular pattern. 
         [0028]      FIG. 2  shows a perspective view of one embodiment of the coil cleaning apparatus  10 . A first fluid delivery system  14  is mounted through the back of the housing  12 , and a second fluid delivery system  16  is mounted through the top of the housing  12  with an elbow connector  40  to minimize the vertical dimension of the coil cleaning apparatus  10 . The first and second fluid delivery systems  14 ,  16  include valves  34 ,  44  for controlling the flow of the first and second fluids. Both first and second fluid delivery systems  14 ,  16  may be connected to tubes, hoses, valves, and similar fluid delivery structures. 
         [0029]    The second fluid delivery system comprises a channel-style nozzle  20  with a plurality of apertures  24  for discharging a second fluid, typically a compressed gas. In one embodiment, the channel-style nozzle  20  extends generally parallel to the longer side of the housing  12  and is positioned near the front and bottom of the housing  12 . The apertures  24  are positioned in front of the first fluid delivery system nozzle (not pictured). In one embodiment, the apertures are spaced equidistance along the length of the channel-style nozzle  20  and have a diameter of approximately  3  millimeters. It will be understood by one skilled in the art that the number, size, and spacing of apertures  24  may be varied as needed to disperse and force the liquid fluid through the coil  50 . Typically, gaseous fluid is delivered at 620 to 689 kilopascals (90 to 100 pounds per square inch) and 0.014 to 0.028 cubic meters per second (30 to 60 cubic feet per minute). The channel-style nozzle  20  is comprised of a material that can withstand high air pressure, typically brass, copper, PVC, or a similar material. 
         [0030]      FIG. 3  shows a perspective view of an alternate embodiment of the coil cleaning apparatus  10 . In this embodiment, the first and second fluid delivery systems  14 ,  16  are mounted through the back of the housing  12 . Mounting the second fluid delivery system  16  through the back of the housing improves flow dynamics by limiting the number of changes in direction the fluid must make before reaching the discharge point. The second fluid delivery system  16  may be detachably mounted through the back of the housing  12  with a threaded connector  28  or permanently mounted. 
         [0031]    The second fluid delivery system includes a channel-style nozzle  20  with a plurality of apertures  24  for discharging a second fluid, typically a compressed gas. The channel-style nozzle  20  extends generally parallel to the longer side of the housing  12  and is positioned near the front and bottom of the housing  12 . The apertures are spaced equidistance along the section of the channel-style nozzle  20  that is positioned in front of the discharge nozzle of the first fluid delivery system (not pictured). It will be understood by one skilled in the art that the number, size, and spacing of apertures  24  may be varied to accommodate variations in air compressor ratings and as needed to disperse and force the first fluid through the coil. 
         [0032]    Typically, gas is delivered at 620 to 689 kilopascals (90 to 100 pounds per square inch) and 0.014 to 0.028 cubic meters per second (30 to 60 cubic feet per minute). 
         [0033]    Both the first and second fluid delivery systems  14 ,  16  include valves  34 ,  46  configured to allow the operator to adjust the flow rate of the first and second fluid, respectively. Both valves  34 ,  46  are positioned near the housing  12  of the coil cleaning apparatus  10  for ease of access. 
         [0034]    In one embodiment, the housing  12  is a rectangular box open on one end. The housing  12  includes a seal  48  around its open outer edge that contacts the coil  50  during operation. The seal  48  helps prevent loss of liquid fluid from the front of the housing  12  and prevents the housing  12  itself or the channel-style nozzle  20  from damaging the coil  50  if pressed too firmly against it. The seal  48  may be a brush, foam, or similar structure. 
         [0035]      FIG. 4  shows a front elevation view of one embodiment of the coil cleaning apparatus  10 . The housing  12  contains a first nozzle  22  connected to the first fluid delivery system  14  and a channel-style nozzle  20  with a plurality of apertures  24  connected to the second fluid delivery system  16 . The nozzle  22  of the first fluid delivery system  14  is secured within the housing  12  by a metal coil  26 , which wraps around the first fluid delivery nozzle  22  and the channel-style nozzle  20 . In one embodiment, the channel-style nozzle  20  extends generally parallel to the longer side of rectangular-shaped housing  12  and is positioned downstream of the first fluid delivery nozzle  22  and below the nozzle exit point  21  such that the channel-style nozzle  20  does not interrupt the flow of the first fluid and picks up a portion of the liquid that would otherwise be lost to gravity. The nozzle  20  of the second fluid delivery system is positioned to direct the second fluid discharge stream into the first fluid discharge stream. It will be understood by one skilled in the art that the positioning and shape of the second fluid discharge nozzle may be varied to achieve the same result. 
         [0036]    The first fluid delivery system is mounted through the back of the housing  12  and the second delivery system is mounted through the top of the housing  12 . The second fluid delivery system includes an elbow connector  40  outside the housing  12  to reduce the vertical dimension of the coil cleaning apparatus  10 . 
         [0037]    Both first and second fluid delivery systems  14 ,  16  include a valve  34 ,  44  for adjusting fluid flow. Both valves  34 ,  44  are positioned near the housing  12  of the coil cleaning apparatus  10  for ease of access. Typically, the first fluid (liquid) is ejected at a rate of 3.8 to 18.9 liters per minute (1 to 5 gallons per minute) and the second fluid (gaseous) is delivered at 620 to 689 kilopascals (90 to 100 pounds per square inch) and 0.014 to 0.028 cubic meters per second (30 to 60 cubic feet per minute). 
         [0038]      FIG. 5  shows a front elevation view of an alternate embodiment of the coil cleaning apparatus  10 . The housing  12  contains a first nozzle  22  connected to the first fluid delivery system  14 , a second nozzle  23  connected to a cleaning fluid delivery system  15 , and a channel-style nozzle  20  with a plurality of apertures  24  connected to the second fluid delivery system  16 . The first fluid may be water; the cleaning fluid may be a solvent or detergent; and the second fluid may be a compressed gas. In one embodiment, the channel-style nozzle  20  extends generally parallel to the longer side of an oval-shaped housing  12  and is positioned downstream of the nozzles  22 ,  23  and below the fluid exit points  21 ,  25  such that the channel-style nozzle  20  does not interrupt the flow of the first fluid or cleaning fluid exiting the nozzles  22 ,  23 . 
         [0039]    The nozzles  22 ,  23  of the first fluid delivery system  14  and cleaning fluid delivery system  15  are mounted through the back of the housing  12 . The nozzles  22 ,  23  may also be connected to tubes, hoses, valves, and similar fluid delivery structures. In one embodiment, the first fluid delivery nozzle  22  is attached to a handle  18 . The handle  18  is positioned to the side of and rearward of the cleaning fluid system  15  so that it is accessible for operation of the coil cleaning apparatus  10 . In an alternate embodiment, a handle of the cleaning fluid delivery system  15  is used for operation of the coil cleaning apparatus  10 . The cleaning fluid delivery system  15  may comprise a squeeze trigger  27  or similar mechanism configured to discharge the cleaning fluid. The first fluid and cleaning fluid delivery nozzles  22 ,  23  are permanently or detachably secured to the housing  12  in a manner that prevents movement during operation. The first fluid and cleaning fluid delivery nozzles  22 ,  23  may contain a single fluid exit point  21 ,  25  as depicted in  FIG. 4, 5  or a plurality of apertures distributed in a variety of patterns. Typically, water is discharged from the first fluid delivery system  14  in a cone-shaped spray. The cleaning fluid may be discharged from the cleaning fluid delivery system  15  as a foam or liquid spray as needed prior to or in combination with discharge of the first and second fluids. 
         [0040]    The second fluid delivery system  16  is mounted through the side of the housing  12 . Side mounting provides a direct route for gas through the second fluid delivery system  16 , which optimizes flow dynamics. The second fluid delivery system comprises a quick coupler  29  for connection to the second fluid source. In one embodiment, the channel-style nozzle  20  is secured to the housing  12  through permanent means, such as through the use of adhesives. In an alternate embodiment, the channel-style nozzle  20  is secured utilizing non-permanent means allowing for replacement of both the channel-style nozzle  20  and the first fluid and cleaning fluid delivery nozzles  22 ,  23 . For example, the channel-style nozzle  20  may be secured by the use of a spring mechanism or a threaded connector. 
         [0041]    The channel-style nozzle  20  contains several apertures  24  for the release of the second fluid, which is typically gaseous. In one embodiment, the apertures  24  are spaced equidistance along the length of the channel-style nozzle  20  in a straight line. The apertures  24  are oriented to direct fluid flow toward the first fluid discharge stream such that the first and second fluids mix downstream of the channel-style nozzle  20 . It will be understood by one skilled in the art that the shape and orientation of the channel-style nozzle  20  and number, size, and spacing of apertures  24  may be varied to accommodate variations in air compressor ratings and as needed to disperse and force the first fluid through the coil. Typically, air is delivered at 620 to 689 kilopascals (90 to 100 pounds per square inch) and 0.014 to 0.028 cubic meters per second (30 to 60 cubic feet per minute). 
         [0042]    Vent holes  30  are located at the back of the housing  12 , opposite the side open for fluid delivery. The vent holes  30  allow air movement through the housing, which reduces pressure on the back wall of the housing. 
         [0043]      FIG. 6  shows a side view of one embodiment of the coil cleaning apparatus  10 . In this embodiment, the first fluid delivery system  14  comprises a nozzle  22  that is mounted through the back of the housing  12  with an adjustable hose clamp  32   a  and a handle  18  which remains outside of the housing  12 . The first fluid delivery system  14  has a handle lever  34  for adjusting the flow rate of the fluid. Additionally, the first fluid delivery system  14  comprises a rotation-style adjustment knob  36  configured to allow an operator to change the pattern of fluid discharge from the nozzle ( 22 ,  FIG. 4, 5 ). For instance, an operator may be able to select between a jet and a cone-shaped discharge. 
         [0044]    The second fluid delivery system  16  is mounted through the top of the housing  12 . A vertical channel  38  extends from the inside of the housing  12  through a hole in the top of the housing  12 . The vertical channel  38  may be permanently or detachably fixed to the housing  12 . A threaded elbow-type connector  40  is placed at the top of the vertical channel  38  to direct flow from the fluid source into the inner-housing channel-style nozzle ( 20 ,  FIG. 2-5 ). The elbow connector  40  reduces the vertical dimension of the apparatus and aligns the first and second delivery systems  14 ,  16  in the back of the housing  12  for ease of operation. A flexible tube  42  is attached to the elbow connector  40  with an adjustable hose clamp  32   b.  A valve  44  is connected to the opposite end of the flexible tube with another adjustable hose clamp  32   c.  The valve  44  is configured to allow the operator to adjust the flow of the second fluid. 
         [0045]    The first and second fluid delivery systems  14 ,  16  are mounted to the housing  12  in a manner that allows the operator to hold the apparatus by the spray nozzle handle  18  of the first fluid delivery system  14 . Valves  34 ,  36 ,  44  are positioned to allow the operator to adjust the parameters of fluid discharge, including flow and discharge pattern, without interrupting the cleaning process. The operator may completely stop the flow of one fluid if it is advantageous to do so. For instance, the operator may choose to first use compressed gas to remove loose debris and subsequently use the combination of liquid and gas to remove the remaining contaminants. 
         [0046]      FIG. 7  shows a side view of an alternate embodiment of the coil cleaning apparatus  10 . In this embodiment, the first fluid delivery system  14  comprises a nozzle  22  that is integrally mounted through the back of the housing  12  and a handle  18  which remains outside of the housing  12 . The first fluid delivery system  14  has a squeeze lever  35  located on the handle  18  for adjusting the flow rate of the fluid. Additionally, it includes a rotation-style adjustment knob  36  configured to allow an operator to change the pattern of fluid discharge from the first fluid delivery nozzle ( 22 ,  FIG. 4, 5 ). 
         [0047]    The second fluid delivery system  16  is mounted through the top of the housing  12 . A vertical channel  38  extends from the inside of the housing  12  through a hole in the top of the housing  12 . The vertical channel  38  may be permanently or detachably fixed to the housing  12 . A threaded elbow-type connector  40  is placed at the top of the vertical channel  38  to direct flow from the fluid source into the inner-housing channel-style nozzle ( 20 ,  FIG. 1-5 ). The elbow connector  40  reduces the vertical dimension of the apparatus and aligns the first and second delivery systems  14 ,  16  in the back of the housing  12  for ease of operation. A flexible tube  42  is attached to the elbow connector  40  with an adjustable hose clamp  32   b.  A valve  44  is connected to the opposite end of the flexible tube with another adjustable hose clamp  32   c.  The valve  44  is configured to allow the operator to adjust the flow of the second fluid. 
         [0048]    Valves  35 ,  36 ,  44  are positioned to allow the operator to adjust the parameters of fluid discharge, including flow and discharge pattern, without interrupting the cleaning process. The operator may completely stop the flow of one fluid if it is advantageous to do so. For instance, the operator may choose to first use compressed gas to remove loose debris and subsequently use the combination of liquid and gas to remove the remaining contaminants. Both the first and second fluid delivery systems  14 ,  16  may be equipped with quick couplers  51 ,  52  for easy connection to a fluid source. 
         [0049]    The housing  12  comprises a seal  48  around the front edge that contacts the coil  50  during operation. The seal  48  helps prevent loss of liquid from the front of the housing  12  and prevents the housing  12  itself from damaging the coil  50  if pressed too firmly against it. The seal  48  may be a brush, foam, or similar structure. 
         [0050]    While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.