Abstract:
An air filter for a well is installed within a well casing of the well. The air filter forming an airtight seal around the well casing of the well, such that all the air that enters and exits the well must pass through the air filter. The air filter preferably includes a filter housing, at least one removable gasket and a removable filter cartridge installed within an opening extending through the filter housing. The air filter prevents dirt, dust, bacteria, gaseous chemicals, volatile organic compounds, (VOCs), insects and other air born contaminants from entering and possibly contaminating the well. An air filter may also be installed within a vent pipe extending through a well seal attached to the top of a well casing of a well.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an air filter for a well, and more particularly, to an air filter assembly installed within the well casing of a well to prevent air borne contaminants from entering the well. The air filter assembly of the present invention is preferably designed for application in water wells, but may be applied to other systems such as oil wells, natural gas wells, gasoline fuel dispensing systems and monitoring wells. The air filter assembly of the present invention is designed to prevent pollutants from contaminating a well. 
     A typical water well is established by first drilling a hole in the ground in search of water from a water bearing aquifer. Once water is reached by the drill, a well casing is inserted into the bore hole to preserve the sides of the well. The well casing is typically a steel or plastic pipe installed while drilling a well, to prevent collapse of the well bore hole and to allow placement of a submersible pump and other equipment. The well casing typically extends several inches above the ground. A submersible pump is inserted into the well below the water level to pump water from the aquifer. One end of a drop pipe is attached to the submersible pump to draw water out of the well. The other end of the drop pipe is attached to a discharge pipe for carrying water to a pressure tank for distribution and use. 
     To prevent contaminants from entering the well and to protect the inside of the casing and the well, a well cap may be installed on top of the well casing extending above the ground. The well cap is used to cover the top of the well casing pipe and thereby seal the top of the well casing to prevent the entry of contaminants in the well. The well cap is generally used in systems where the discharge pipe for distributing and supplying water is underground. The well cap also typically includes a conduit box for routing electrical wires from the submersible pump to an electrical power source. The well cap is typically not airtight, and therefore allows air to enter the well around openings between the well cap and the top of the well casing. This opening allows air to flow in and out of the well during pressure changes. In addition to the well cap, a wire screen may be attached to the top of the well casing to prevent large objects from contaminating the well. 
     As an alternative to the well cap, a well seal may also be used to cover the top of the well casing. The well seal includes a gasket that seals the top of the well casing to prevent entry of contaminants in the well. The well seal is generally used in systems where the discharge pipe for distributing and supplying water comes up through the top of the well casing. The well seal also typically includes openings for a screened vent pipe and a conduit box to pass through the gasket. The screened vent pipe allows air to enter and exit the well during pressure changes. The conduit box is used for routing electrical wires from the submersible pump to an electrical power source. The well seal provides a seal around the discharge pipe, vent pipe and conduit box. However, air enters the well through the vent pipe. The vent pipe screen functions to reduce contaminant entry into the well by preventing large objects from entering the well. 
     During use, the submersible pump pulls air into the well. The air may include dirt, dust, bacteria, gaseous chemicals, volatile organic compounds (VOCs), insects and other air born contaminants that may contaminate the well and should be removed. When the pump stops, a change in pressure forces air out of the well. In addition, the normal changes in atmospheric pressure cause air to flow in and out of the well. There is nothing in the prior art to remove air born contaminants from entering a well and possibly contaminating the water in the well. The well cap and well seal do not prevent dirt, dust, bacteria, gaseous chemicals, VOCs and other air born contaminants from entering the well and possibly contaminating the water. 
     Accordingly, there is a need for an air filter for a well. The air filter being installed within the well casing of the well or attached to the side of the well casing for preventing air borne contaminants from entering the well. The air filter of the present invention removes dirt, dust, bacteria, gaseous chemicals and VOCs from the air, and stops insects from entering the well. 
     SUMMARY OF THE INVENTION 
     The present invention provides an air filter for a well. The well of the present invention preferably includes a submersible pump inserted within a well casing of a well below the water level to pump water from a water bearing aquifer. A drop pipe is connected between the submersible pump and a discharge pipe for distribution of the water from the well. The well of the present invention may also be a monitoring well that typically does not include the submersible pump, drop pipe or discharge pipe, but simply includes a well casing. 
     An air filter assembly is preferably installed within the well casing of a well forming an airtight seal between the casing and the filter assembly, so that all the air that enters and exits the well must pass through the filter. The filter assembly preferably includes a housing, at least one gasket and a removable filter cartridge. The air filter assembly of the present invention is designed for use on well casings of various diameters. Therefore various diameter housings, gaskets, and cartridges may be used to fit the various diameter well casings. As mentioned above, different diameter gaskets may be used to fit the different diameter well casings. The gaskets preferably forming an airtight seal and having at least one opening extending therethrough for receiving a relief valve and submersible pump wires. The airtight seal is maintained around the relief valve and pump wires. Grommets may also be used to perfect the seal around the relief valve and pump wires. Alternatively, an adjustable gasket may be used to fit the different diameter well casings. For example, the adjustable gasket could have a plurality of layers, like a roll of tape, that may be removed from the gasket or re-applied to the gasket to vary the diameter of the gasket. The relief valve and pump wires that extend through the gasket are preferably sealed between layers of the adjustable gasket or sealed by at least one grommet. 
     The present invention includes several different embodiments. In a first embodiment, an air filter assembly is installed within a top portion of a well casing having a well cap attached to the top of the well casing. In a second embodiment, an air filter is installed within a vent pipe extending through a well seal attached to the top of a well casing. In a third embodiment, an air filter assembly is installed within a branch pipe extending from an opening in one side of a well casing. In a fourth embodiment, an air filter assembly is installed within a top portion of a well casing of a monitoring well. 
     Various other features, objects, and advantages of the invention will be made apparent to those skilled in the art from the following drawings and detailed description of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial cross-sectional exploded schematic representation of a well system according to a first embodiment of the present invention, showing an air filter assembly installed under a well cap of a well casing of a well; 
     FIG. 2 is an enlarged partial cross-sectional view of the air filter assembly installed under the well cap of the well casing of the well of FIG. 1; 
     FIG. 3 is a partial cross-sectional exploded schematic representation of a well system according to a second embodiment of the present invention, showing an air filter installed within a well seal attached to the top of a well casing of a well; 
     FIG. 4 is an enlarged partial cross-sectional view of the air filter installed within the well seal attached to the top of the well casing of the well of FIG. 3; 
     FIG. 5 is a partial cross-sectional exploded schematic representation of a well system according to a third embodiment of the present invention, showing an air filter assembly installed on the side of a well casing of a well; 
     FIG. 6 is an enlarged partial cross-sectional view of the air filter assembly installed on the side of the well casing of the well of FIG. 5; 
     FIG. 7 is a partial cross-sectional exploded schematic representation of a monitoring well according to the present invention, showing an air filter assembly installed in a well casing of the monitoring well; and 
     FIG. 8 is an enlarged partial cross-sectional view of the air filter assembly installed in the well casing of the monitoring well of FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a schematic representation of one embodiment of a well system  10  comprising an air filter assembly  12  installed under a well cap  14  on top of a well casing  16  of a well  18 . A submersible pump  20  is installed in the well  18  below the water level to pump water from a water bearing aquifer  22 . A first end  24  of a drop pipe  26  is connected to the output  32  of the submersible pump  20 . A second end  28  of the drop pipe  26 , opposite the first end  24 , is connected to a pitless adapter  30 , which is connected to a discharge pipe  34  for distribution of water from the well. Water flows from the submersible pump  20  through the drop pipe  26  and pitless adapter  30  into the discharge pipe  34 . The submersible pump  20  is preferably electrically powered and thus, includes a plurality of electrical wires  36  connected to the pump  20  that extend up through the well casing  16  and out through the well cap  14  for connection to an external electrical power source (not shown). In the well cap  14 , the wires  36  travel through a conduit box  38  into a conduit  40  which leads the wires underground for connection to the power source. 
     FIG. 2 shows an enlarged partial cross-sectional view of a top portion  42  of the well casing  16  that extends above the ground. The well casing  16  preferably having a circular sidewall  44  with an inner surface  46  and an outer surface  48 . The air filter assembly  12  is preferably installed under the well cap  14  within the top portion  42  of the well casing  16 . The air filter assembly  12  preferably includes a cylindrically shaped filter housing  50  with a filter cartridge  52  removably inserted within an opening  54  extending through the center of the filter housing  50 . The cylindrically shaped filter housing  50  comprises an outer sidewall  56 , a top surface  58 , a bottom surface  60 , and a doughnut shaped gasket  62  removably attached to the top surface  58  of the housing. The housing gasket  62  extends outwardly from the circular opening  54  past the outer sidewall  56  for sealing the housing  50  to the top of the well casing  16 . In addition, an o-ring seal  64  is formed around the outer sidewall  56  of the housing  50  for sealing the outer sidewall  56  housing against the inner surface  46  of the sidewall  44  of the well casing  16 . 
     The housing gasket  62  attached to the top of the housing  50  preferably includes at least two relatively small openings  66 ,  68  extending therethrough for receiving a relief valve  70  and the plurality of pump wires  36 . The relief valve  70  is sealed in the first opening  66  and functions by allowing airflow through the valve  70  once the filter cartridge  52  becomes clogged. As air flows through the relief valve  70 , an alarm  72  incorporated into the relief valve  70  emits an audio signal signifying that the filter cartridge  52  is clogged and should be to replaced. The second opening  68  allows the plurality of pump wires  36  to pass through the filter housing  50  and on to the conduit box  38  and conduit  240  for connection to the power source. Both the first and second openings  66 ,  68  may include grommets  74 ,  76  to assure an airtight seal around the relief valve  70  and plurality of pump wires  36  that extend through the openings  66 ,  68  in the housing gasket  62 . 
     The filter cartridge  52  removably inserted within the opening  54  of the filter housing  50  is also preferably cylindrically shaped with an outer sidewall  78 , a top surface  80 , and a bottom surface  82 . A doughnut shaped gasket  84  is preferably removably attached to the top surface  80  of the cartridge  52  for sealing around the opening  54  extending through the housing  50  and allowing air to flow through the cartridge  52 . The cartridge gasket  84  preferably extends outwardly past the outer sidewall  78  for sealing against the housing gasket  62 . Once the filter cartridge  52  is installed in the filter housing  50 , an airtight seal is formed between the cartridge gasket  84  and the housing gasket  62 . Therefore, all air flowing into and out of the well must flow through the filter cartridge  52 . The cartridge gasket  84  may preferably include a relatively small opening  86  extending therethrough for receiving the plurality of pump wires  36  to pass through. The opening  86  may include a grommet  88  to assure an airtight seal around the plurality of pump wires  36  as they pass through the cartridge gasket  84 . 
     The filter cartridge of the present invention is preferably a canister type filter element that is easily removable from the filter housing for replacement purposes. The filter cartridge is preferably made of special reinforced paper that won&#39;t tear apart and won&#39;t deteriorate and fall into the well. An example filter cartridge that may be used in the present invention is a PharmaGard™ V-II Series Filter Cartridge manufactured by Seitz Division of U.S. Filter Company, or equivalent. The gaskets are also preferably removable from the housing and cartridge, so that they don&#39;t need to be replaced when the cartridge is replaced. The gaskets are preferably made of a neoprene rubber material that won&#39;t deteriorate over time. 
     The air filter assembly of the present invention is designed for use on well casings of various diameters. The type of gaskets used in the present invention may be of several different embodiments. In a first embodiment, gaskets of different diameters are used to fit different diameter well casings. In an alternate embodiment, an adjustable gasket may be used to fit on different diameter well casings. For example, the adjustable gasket could have a plurality of layers, like a roll of tape, that may be removed from the gasket or re-applied to the gasket to vary the diameter of the gasket. In this embodiment, the relief valve and pump wires are sealed between layers of the adjustable gasket. 
     FIGS. 3 and 4 illustrate another embodiment of the present invention. FIG. 3 is similar to FIG. 1 except that the well system  90  includes a well seal  92  attached to the top of a well casing  94  instead of a well cap. The well system  90  comprises a submersible pump  96  and a drop pipe  98  connected to the output  100  of the pump  96  that extends up through the top of the well seal  92  to a discharge pipe (not shown). 
     A well seal is typically used to cover the top of a well casing to prevent the entry of surface runoff into the well during flooding. A well seal differs from a well cap in that the well seal has a gasket to seal the top of the well casing, whereas a well cap does not include a gasket to seal the top of the well casing. A well seal typically includes a screened vent pipe that extends through the gasket to allow air to flow into and out of the well during changes in pressure. The screen is necessary to reduce contaminant entry into the well. A well seal also typically includes a conduit box and conduit that extends through the gasket to allow a plurality of electrical wires from the submersible pump to pass through for connection to an external power source. 
     Referring again to FIGS. 3 and 4, an air filter  102  is preferably installed within a vent pipe  104  extending through the well seal  92  attached to the top of the well casing  94 . The vent pipe  104  allows air to flow into and out of the well  106 . FIG. 4 shows an enlarged partial cross-sectional view of the top of the well casing  94 . The well seal  92  preferably includes a gasket  108  sandwiched between a bottom plate  110  and a top plate  112 . The well seal  92  further includes a conduit box  114  and a conduit  242  that allow a plurality of electrical wiring  116  from the submersible pump  96  to be connected to an external power source (not shown). The vent pipe  104  includes a screen  118  and the air filter  102  to remove dirt, dust, bacteria, gaseous chemicals, VOCs, insects and other contaminants from entering the well. 
     FIGS. 5 and 6 illustrate yet another embodiment of the present invention. FIG. 5 illustrates a schematic representation of a commercial or municipal well system  120  that typically has a larger diameter well casing  122  than residential water wells. The well system  120  comprises an air filter assembly  124  installed within a branch pipe  126  extending from one side of the well casing  122 . 
     Similar to FIGS. 1 and 3, a submersible pump  128  is installed in a well  130  below the water level to pump water from a water bearing aquifer  132 . A drop pipe  134  is connected to the output  136  of the submersible pump  128  and extends up through the well casing  122  to a discharge pipe  138  for distribution and use. The top of the well casing  122  is sealed around the drop pipe  134 . A plurality of electrical wires  140  connected to the pump  128  extend up through the well casing  122  for connection to an external electrical power source (not shown). 
     FIG. 6 shows an enlarged partial cross-sectional view of a top portion  142  of the well casing  122  that extends above ground level and includes a branch pipe  126  extending from an opening  144  on one side of the well casing  122  for allowing air to flow through the well. The air filter assembly  124  is installed within the branch pipe  126 . The drop pipe  134  extends through the top of the well casing  122  and is connected to the discharge pipe  138 . A well seal  146  seals the top of the well casing  122  around the drop pipe  134 . The branch pipe  126  includes a first section  148  with the air filter assembly  124  installed therein and a second section  150  with a fan assembly  152  installed therein for moving air through the well. 
     The branch pipe  126  preferably includes a circular sidewall  154  with an inner surface  156  and an outer surface  158 . The air filter assembly  124  preferably includes a filter housing  160  with a filter cartridge  162  removably inserted within an opening  164  extending through the center of the filter housing  160 . The cylindrically shaped filter housing  160  preferably comprises an outer sidewall  166 , a top surface  168 , a bottom surface  170 , and a doughnut shaped gasket  172  removably attached to the top surface  168  of the housing  160 . The housing gasket  172  extends outwardly from the circular opening  164  past the outer sidewall  166  for sealing the housing  160  to the first section  148  of the branch pipe  126 . In addition, an o-ring seal  174  is formed around the outer sidewall  166  of the housing  160  for sealing against the inner surface  156  of the sidewall  154  of the branch pipe  126 . 
     The housing gasket  172  preferably includes at least two relatively small openings  176 ,  178  extending therethrough for receiving a relief valve  180  and the plurality of pump wires  140 . The relief valve  180  is sealed in the first opening  176  and functions by allowing airflow through the valve  180  once the filter cartridge  162  becomes clogged. As air flows through the relief valve  180 , an alarm  244  incorporated into the relief valve  180  emits an audio signal signifying that the filter cartridge  162  is clogged and should be to replaced. The second opening  178  allows the plurality of pump wires  140  to pass through the filter housing  160  for connection to the fan assembly  152  and a power source (not shown). Both the first and second openings  176 ,  178  may include grommets  182 ,  184  to assure an airtight seal around the relief valve  180  and plurality of pump wires  140 . 
     The filter cartridge  162  removably inserted within the opening  164  of the filter housing  160  is also preferably cylindrically shaped with an outer sidewall  186 , a top surface  188 , and a bottom surface  190 . A doughnut shaped gasket  192  is preferably removably attached to the top surface  188  of the cartridge  162  for sealing around the opening  164  extending through the housing  160  and allowing air to flow through the cartridge  162 . The cartridge gasket  192  extends outwardly past the outer sidewall  186  for sealing against the housing gasket  172 . Once the filter cartridge  162  is installed in the filter housing  160 , an airtight seal is formed between the cartridge gasket  192  and the housing gasket  172 . Therefore, all air flowing into and out of the well  106  must flow through the filter cartridge  162 . The cartridge gasket  192  may preferably include a relatively small opening  194  extending therethrough for allowing the plurality of pump wires  140  to pass through. The opening  194  may include a grommet  196  to assure an airtight seal around the plurality of pump wires  140 . 
     FIGS. 7 and 8 illustrate still yet another embodiment of the present invention. FIG. 7 illustrates a schematic representation of a monitoring well  198  that is typically drilled near underground storage tanks for monitoring ground water  246  for possible contaminants leaking from the underground storage tanks. The monitoring well  198  comprises an air filter assembly  200  installed under a well cap  202  on top of a well casing  204 . 
     FIG. 8 shows an enlarged partial cross-sectional view of a top portion  206  of the well casing  204 . The well casing  204  preferably includes a circular sidewall  206  with an inner surface  208  and an outer surface  210 . The air filter assembly  200  is preferably installed under the well cap  202  within the top portion  206  of the well casing  204 . The air filter assembly  200  preferably includes a filter housing  212  with a filter cartridge  214  removably inserted within an opening  216  extending through the center of the filter housing  212 . The filter housing  212  is preferably cylindrically shaped with an outer sidewall  218 , a top surface  220 , a bottom surface  222 , and a doughnut shaped gasket  224  removably attached to the top surface  220  of the housing  212 . The housing gasket  224  extends outwardly from the circular opening  216  past the outer sidewall  218  for sealing the housing  212  to the top of the well casing  204 . In addition, an o-ring seal  226  is formed around the outer sidewall  218  of the housing  212  for sealing the outer sidewall  218  against the inner surface  208  of the sidewall  206  of the well casing  204 . 
     The housing gasket  224  attached to the top of the filter housing  212  preferably includes at least one relatively small opening  228  extending therethrough for receiving a relief valve  230  therein. The opening  228  may include a grommet  246  to assure an airtight seal around the relief valve  230 . The relief valve  230  allows airflow through the valve once the filter cartridge  214  becomes clogged. As air flows through the relief valve  230 , an alarm  244  incorporated within the relief valve  230  emits an audio signal signifying that the filter cartridge  214  is clogged and should be to replaced. 
     The filter cartridge  214  removably inserted within the opening  216  of the filter housing  212  is also preferably cylindrically shaped with an outer sidewall  232 , a top surface  234 , and a bottom surface  236 . A doughnut shaped gasket  238  is preferably removably attached to the top surface  234  of the cartridge  214  for sealing around the opening  216  and allowing air to flow through the cartridge  214 . The cartridge gasket  238  extends outwardly past the outer sidewall  232  for sealing against the housing gasket  224 . Once the filter cartridge  214  is installed in the filter housing  212 , an airtight seal is formed between the cartridge gasket  238  and the housing gasket  224 . The well cap  202  is positioned on top of the well casing  204  above the air filter assembly  200 . All air flowing into and out of the well must flow through the filter cartridge  214 . 
     While the invention has been described with reference to preferred embodiments, those skilled in the art will appreciate that certain substitutions, alterations and omissions may be made without departing from the spirit of the invention. Accordingly, the foregoing description is meant to be exemplary only, and should not limit the scope of the invention set forth in the following claims.