Abstract:
The invention provides an apparatus and method for removing diatomaceous earth and contaminants from a filter and for filtering liquid using diatomaceous earth. Embodiments of the method can include a washdown process, a backwash process, and a filtering process. Some embodiments of the apparatus can include one or more filter cartridges with cartridge tubes to increase flow during the backwash process. Some embodiments of the apparatus can include a backwash sprayer to disturb contaminants during the backwash process. Some embodiments of the apparatus can include a removable lid to access the filter cartridges during the washdown process.

Description:
BACKGROUND 
     Diatomaceous earth (“DE”) filters are often used to filter the water of swimming pools, spas, water features, etc. DE filters typically include a septum with relatively large pores that DE cannot pass through. Adding a solution of water and DE to the filter can form a cake of DE on the surface of the septum. The addition of the DE to the septum can create a smaller porous structure to improve the filtering capability of the septum. However, contaminants caught in the DE over time can reduce the filtering capability of the septum. As a result, the DE must be removed from the septum and reapplied. Various techniques have been used to remove the DE from the septum. These conventional techniques generally do not remove all the contaminants from the septum, allowing the contaminants to build up and eventually affect the performance of the filter. 
     SUMMARY 
     In one embodiment, the invention provides a method of removing diatomaceous earth and contaminants from a filter. The method can include opening a drain in a bottom tank and removing a lid to expose one or more filter cartridges. The method can also include washing down the filter cartridges to remove the diatomaceous earth and the contaminants from a septum of the filter cartridges. The method can further include washing the diatomaceous earth and the contaminants out of the bottom tank through the drain, replacing the lid, and closing the drain. 
     Another embodiment of a method of removing diatomaceous earth and contaminants from a filter can include setting a backwash valve to a backwash position to reverse liquid flow. The method can include directing liquid flow from an interior to an exterior of one or more filter cartridges. The method can also include directing liquid flow from a filter interior through a cartridge tube having holes to the exterior through a septum in order to remove the diatomaceous earth and the contaminants from the septum. The method can further include directing liquid flow through a backwash sprayer to create turbulence in a bottom tank and directing liquid flow from the exterior of the filter cartridge and from the bottom tank to a backwash pipe. 
     Some embodiments of the invention provide a method of filtering contaminants form a liquid using diatomaceous earth. The method can include removing substantially all air form a filter tank, spraying unfiltered liquid into the filter tank to substantially fill the filter tank with liquid, and continuing to spray unfiltered liquid into the filter tank to create turbulence. The method can also include directing the unfiltered liquid from an exterior of one or more filter cartridges through a septum coated with a solution including diatomaceous earth to an interior of the filter cartridges in order to filter the liquid. The method can further include sealing the filtered liquid within the interior of the filter cartridges from the unfiltered liquid and directing the filtered liquid through the filter cartridges to an outlet. 
     Some embodiments of the invention provide a diatomaceous earth filter for filtering contaminants from liquid. The filter can include one or more filter cartridges each including a septum coated with a solution including diatomaceous earth. The filter cartridges can also include a cartridge tube with holes to increase liquid flow during a backwash process. The filter can also include a backwash sprayer to spray liquid during the backwash process in order to disturb contaminants in a bottom portion of a filter tank. 
     Another embodiment of the invention provides a diatomaceous earth filter including a bottom tank with a drain. The filter also includes one or more filter cartridges at least partially positioned in the bottom tank. The filter cartridges can include a septum coated with a solution including diatomaceous earth. The filter can also include a removable lid positioned over the filter cartridges and a clamp that secures the removable lid to the bottom tank. 
     Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cut-away perspective view of a DE filter according to one embodiment of the invention. 
         FIGS. 2A and 2B  are exploded views of the DE filter of  FIG. 1 . 
         FIG. 3  is a schematic view of a clamp, a lid, a bottom tank, and an o-ring of the DE filter of  FIG. 1 . 
         FIG. 4  is a perspective view of a clamp of the DE filter of  FIG. 1 . 
         FIGS. 5A-5D  are flow charts of processes for operating a DE filter according to embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
       FIGS. 1 ,  2 A, and  2 B illustrate a DE filter  100  according to one embodiment of the invention. As shown in  FIG. 1 , the DE filter  100  can include an air relief valve  105 , a pressure gauge  107 , a lid  110 , one or more filter cartridges  135 , a clamp  145 , a bottom tank  170  including a drain  195 , and a backwash valve  220 . In one embodiment, the lid  110  and the bottom tank  170  can be constructed of chemical-resistant, fiberglass-reinforced polypropylene to withstand pressures created in the DE filter  100 . In some embodiments, the DE filter  100  can withstand internal pressures up to about 50 pounds per square inch. 
     As shown in  FIG. 2A , the DE filter  100  can include a compression spring  115 , an adapter  120 , a top cartridge manifold  125 , and an air bleeder tube  130 . As shown in  FIG. 2B , the DE filter  100  can include one or more cartridge tubes  137 , a backwash sprayer  138 , a bottom cartridge manifold  140 , and o-ring  150 , a ring backup  155 , a baffle assembly  160 , and an outlet pipe  165 . As also shown in  FIG. 2B , the clamp  145  can include a barrel nut  175 , a large inside diameter washer  180 , a clamp spring  185 , and a small inside diameter washer  190 . As further shown in  FIG. 2B , the bottom tank  170  can include the drain  195 , an inlet adapter  200 , an outlet adapter  205 , a first o-ring  210 , and a second o-ring  215 . 
     As shown in  FIG. 2B , the inlet adapter  200  can include threads that can mate with threads of the baffle assembly  160 . The first o-ring  210  can have a diameter substantially equal to a diameter of the threads of the inlet adapter  200 . The first o-ring  210  can fit over the threads of the inlet adapter  200  and form a water-tight seal between the inlet adapter  200  and the bottom tank  170  when the inlet adapter  200  is coupled to the baffle assembly  160 . The baffle assembly  160  can spray unfiltered water into the DE filter  100 . As also shown in  FIG. 2B , the outlet adapter  205  can include threads that can mate with threads of the outlet pipe  165 . The second o-ring  215  can have a diameter substantially equal to a diameter of the threads of the outlet adapter  205 . The second o-ring  215  can fit over the threads of the outlet adapter  205  and form a water-tight seal between the outlet adapter  205  and the bottom tank  170  when the outlet adapter  205  is coupled to the outlet pipe  165 . 
     In one embodiment, the inlet adapter  200 , the outlet adapter  205 , and the drain  195  can each have an internal diameter of at least about two inches to enable sufficient water flow. In general, the high flow design of the DE filter  100  (including the filter cartridges  135 ) reduces energy costs associated with operating the pump (not shown). 
     As shown in  FIG. 2B , the outlet pipe  165  can include an elbow  250  so that an opening  255  of the outlet pipe  165  can be positioned in a substantially vertical position. The opening  255  can include threads. In some embodiments, the opening  255  can include one or more o-rings and/or can be press-fit to be coupled to the bottom manifold  140 . 
     As also shown in  FIG. 2B , the bottom manifold  140  can include arms  257  with filter receivers  260 , an air bleeder receiver  265 , and an outlet  270 . In some embodiments, the outlet  270  of the bottom manifold  140  can include threads that can be coupled to the opening  255  of the outlet pipe  165 . 
     As shown in  FIGS. 2A and 2B , the filter cartridges  135  can each include a cartridge tube  137 , a top end cap  300 , a septum  320 , and a bottom end cap  305 . The top end caps  300  and the bottom end caps  305  of the filter cartridges  135  can be in fluid communication with an inner side of the septum  320  and can provide a flow path for liquid passing through the septum  320 . In one embodiment, the top end caps  300  and/or the bottom end caps  305  can be constructed of urethane. 
     The cartridge tubes  137 , as shown in  FIG. 2B , can be positioned inside each one of the filter cartridges  135  and can extend substantially to the top end caps  300 . The cartridge tubes  137  can have holes along their length and can be open at both ends. During backwashing of the DE filter  100 , the cartridge tubes  137  can deliver a relatively large quantity of water to the top of the filter cartridges  135 . The large quantity of water delivered to the top of the cartridge filters  135  can promote better cleaning of the septum  320 . The DE and the contaminants can be forced off the top of the septum  320  initially and gravity can cause the water to clean succeedingly lower portions of the septum  320  until the septum  320  is substantially entirely clean. In some embodiments, in excess of about 80% of the DE and contaminants can be removed from the septum  320  by using the cartridge tubes  137 , versus about 20% of the DE and contaminants being removed without the cartridge tubes  137 . 
     In one embodiment, the septum  320  can be constructed of polypropylene and can have pores about 25 microns to about 50 microns in diameter. The polypropylene material can be relatively heavy, for example, about 8 ounces per square foot. The polypropylene can also have a coefficient of friction low enough to enable removal of the DE and contaminants from the septum  320 . Water can be applied with low pressure to the septum  320 . Because of the low coefficient of friction of the septum  320 , the low pressure water can quickly remove substantially the entire quantity of DE and contaminants present on septum  320 . In addition, the septum  320  can have a corrugated construction and can have a linear length much greater than a circumference of the filter cartridge  135  (e.g., ten linear feet). The corrugated construction can result in a large amount of filtering area in a minimum amount of space. 
     The filter cartridge  135  can be manufactured in different sizes (e.g., eighteen, twenty-four, and thirty inch heights). The filter cartridges  135  can be manufactured with multiple filtering areas (e.g., fifteen, twenty, and twenty-five square feet). Using multiple filter cartridges  135  in the DE filter  100  can increase the filtering area (e.g., to sixty, eighty, or one-hundred square inches when using four filter cartridges  135 ). In other embodiments, less than four filter cartridges  135 , such as a single filter cartridge  135 , can be used for smaller applications. 
     A larger filtering area can increase the flow rate of water through the DE filter  100 . For example, a DE filter  100  with 60 square feet of filtering area can have a maximum flow rate of about 120 gallons per minute or a turn-over capacity of 86,400 gallons every twelve hours. By contrast, a DE filter  100  with 100 square feet of filtering capacity can have a maximum flow rate of 160 gallons per minute and a turn-over capacity of 115,200 gallons every twelve hours. In addition, a larger filtering area can provide more filtering capacity to extend the time period between filter cleanings. 
     As shown in  FIG. 2A , the top manifold  140  can include a plurality of arms  350  extending from a center support  355 . The ends of the arms  350  can include cartridge plugs  360 . The cartridge plugs  360  can be received by the top end caps  300  of the filter cartridges  135  and can form a water tight seal to prevent water from entering or leaving the filter cartridge  135  via the top end caps  300 . 
     The air bleeder tube  130  can be positioned on the air bleeder receiver  265  of the bottom manifold  140 . The air bleeder tube  130  can extend upward to substantially the top of the DE filter  100  and can be supported by the center support  355  of the top manifold  140 . During operation, water in the bottom manifold  140  passing by the bottom opening of the bleeder tube  130  can have a Venturi effect on the air bleeder tube  130 . The Venturi effect can draw air from the top of the DE filter  100  into the air bleeder tube  130  and force the air out the outlet port  205 . During normal operation, substantially no air should be present in the DE filter  100 . If substantially no air is present in the DE filter  100 , the Venturi effect can draw water from the upper portion of the DE filter  100 . 
     As shown in  FIG. 2A , the adapter  120  can fit over the center support  355  of the top manifold  140  and the air bleeder tube  130 . The spring  115  can fit over the adapter  120  to bias the adapter  120  and the top manifold  140  downward when the lid  110  is in place. Biasing the top manifold  140  downward can force the plugs  360  of the top manifold  125  into the top end caps  300  to seal the upper portions of the filter cartridges  135  and to prevent water from passing through the top end caps  300 . 
     As also shown in  FIG. 2A , in some embodiments, the manual air relief valve  105  can include threads that can mate with threads in an aperture  380  of the lid  110 . The manual relief valve  105  can be opened to allow air and/or water in a top portion of the DE filter  100  to escape. During start-up of the DE filter  100 , the manual relief valve  105  can be opened (e.g., by turning the valve  105  a quarter-turn counter-clockwise) and can allow any air trapped in the DE filter  100  to escape. Once all the air in the DE filter  100  has escaped, water can begin to escape through the manual relief valve  105 , which can generally indicate that substantially all the air in the DE filter  100  has been removed. The manual relief valve  105  can be closed (e.g., by turning the valve  105  a quarter-turn clockwise) enabling pressure to build up in the DE filter  100 . The pressure can force water to flow through the septum  320 , down through the bottom manifold  140 , and out the outlet pipe  165 . 
     As shown in  FIGS. 2B and 3 , the o-ring  150  can be positioned between the lid  110  and the bottom tank  170  and secured by the clamp  145 . The o-ring  150  can be positioned in a lower groove  390  around an upper edge  395  of the bottom tank  170 . A lower edge  392  of the lid  110  can also include an upper groove  397 . The o-ring  150  can provide a seal between the upper groove  397  of the lid  110  and the lower groove  390  of the bottom tank  170 . As also shown in  FIG. 3 , the clamp  145  can be positioned around a flange  400  of the bottom tank  170  and a flange  405  of the lid  110 . A center segment  410  of the clamp  145  can be positioned over the flange  400  of the bottom tank  170  and over the flange  405  of the lid  110 . 
       FIG. 4  further illustrates the clamp  145 , which can include a T-bolt  425  and a trunnion  430 , in one embodiment. A first end  420  of the T-bolt  425  can mount to the clamp  145  in a hinged configuration and a threaded end  422  can pass through the trunnion  430 . The large inside diameter washer  180 , the spring  185 , and the small inside diameter washer  190  can be positioned on the T-bolt  425 . The large inside diameter washer  180  can be positioned over the T-bolt  425  between the barrel nut  175  and the spring  185 . The barrel nut  175  can be tightened to move the large inside diameter washer  180  toward the spring  185 . The spring  185  can bias the small inside diameter washer  190  toward the trunnion  430 . As the barrel nut  175  is tightened onto the T-bolt  425 , the bias of the spring  185  on the trunnion  430  can force a first end  445  and a second end  450  of the clamp  145  toward one another to tighten the clamp  145  around the lid  110  and bottom tank  170 . Securing the clamp  145  around the DE filter  100  can cause the lid  110  to compress the o-ring  150  toward the bottom tank  170  to create a water tight seal of sufficient strength to withstand the pressure applied to the DE filter  100 . 
       FIGS. 5A-5D  illustrate processes for operating the DE filter  100  according to embodiments of the invention. The DE filter  100  operates under pressure, and in order for the DE filter  100  to operate correctly, substantially all air must be removed. When starting the DE filter  100 , the air relief valve  105  can be opened (block  500  of  FIG. 5A ) by turning the air relief valve  105  a quarter turn counter-clockwise. A drain of a swimming pool can also be closed (block  505 ) and can enable a skimmer of the swimming pool to provide water to the DE filter  100 . The pump of the swimming pool, spa, water feature, etc. (not shown) can be started (block  510 ). The pump can draw water from a swimming pool skimmer and can force unfiltered water into the inlet adapter  200  and the baffle assembly  160 . The baffle assembly  160  can spray the unfiltered water into the DE filter  100 . During normal operation, when the DE filter  100  is substantially filled with water, the baffle assembly  160  can create turbulence to assist in dispersing the unfiltered water, and thus any contaminants in the water, to facilitate filtering of the water. 
     As the DE filter  100  fills with water, air in an upper portion of the DE filter  100  can be forced out the air relief valve  105 . Eventually, substantially all of the air in the DE filter  100  can be expelled and water can flow from the air relief valve  105 . An operator can determine (at block  515 ) whether a steady stream of water is exiting the air relief valve  105 . If water is not exiting the air relief valve  105 , the operator can determine (block  520 ) whether a period of time that should be sufficient to fill the DE filter  100  has elapsed (e.g., 30 seconds). If the time period has not elapsed, the operator can continue to monitor the air relief valve (at block  515 ). If the time period has elapsed, the operator can shut the pump down (block  525 ). If the operator observes (block  515 ) a steady stream of water exiting the air relief valve  105 , the DE filter  100  is substantially filled with water and the operator can close the air relief valve  105  (block  527 ) (e.g., by turning the air relief valve  105  a quarter turn clockwise). 
     DE can be added to the DE filter  100  (block  530 ). In one embodiment, the septum  320  of the filter cartridges  135  can include pores having openings of about 25 microns to about 50 microns in size. In one embodiment, for example to achieve a level of filtering for a swimming pool, the operator can add DE to the septum  320  to reduce the size of the openings to about one micron to about five microns in order to filter out dirt, algae, and some forms of bacteria. In other words, the DE filter according to one embodiment of the invention can filter substantially all contaminants is excess of about one micron to about five microns from any liquid able to pass through a one micron to five micron opening. A sufficient quantity of DE can be added to substantially coat the surface of the septum  320  (e.g., one pound of DE for every ten square feet of septum  320  area). The DE can be added to water to form a thin, milky mixture and can then be introduced into the DE filter  100 . The mixture can be drawn into the DE filter  100  through the inlet aperture  200  and distributed by the baffle assembly  160  to coat the septum  320  of the filter cartridges  135 . 
     If this is the first time the DE filter  100  is being run (block  535 ), the operator can record (block  540 ) the pressure inside the DE filter  100 . If this is not the first time the DE filter  100  is being run (block  535 ) (i.e., following a backwash), the operator can check (block  545 ) the pressure to ensure that the pressure in the DE filter  100  is within an operating tolerance (e.g., within four to five pounds per square inch of the recorded pressure). If the pressure is not within the operating tolerance, the operator can turn the pump off (block  525 ). If the pressure is within the operating tolerance, the DE filter  100  can operate to filter the water in the swimming pool, spa, water feature, etc. 
     As shown in  FIG. 5B , the operator can periodically check (block  550 ) the pressure in the DE filter  100 . When the pressure in the DE filter  100  rises above a threshold (e.g., ten to twelve pounds per square inch above the recorded pressure), the DE filter  100  may require cleaning. The operator can shut off (block  555 ) the pump. The operator can determine (block  560 ) whether to clean the DE filter  100  by a washing down process or a backwashing process. 
       FIG. 5C  illustrates a process for washing down the DE filter  100  according to one embodiment of the invention. Before opening the DE filter  100 , the pressure inside the DE filter  100  must be relieved (block  565 ). The pressure in the DE filter  100  can be relieved by opening the air relief valve  105  (e.g., by turning the air relief valve  105  a quarter turn counter-clockwise). Water in the DE filter  100  can also be removed (block  570 ) by opening the drain  195 . The clamp  145  and the lid  110  can be removed (block  575 ). As shown in  FIG. 4 , the clamp  145  can be removed by loosening the barrel nut  175 . The barrel nut  175  can be completely removed or just loosened to a point that the clamp  145  can be removed from the DE filter  100 . Once the clamp  145  is removed, the lid  110  can be removed. 
     With the lid  110  removed, the filter cartridges  135  are exposed. An operator can decide (block  580 ) whether to wash the filter cartridges  135  in place or to remove the filter cartridges  135  for washing. Washing in place (block  585 ) can be accomplished by hosing the filter cartridges  135  down to remove the DE caked on the septum  320 , along with any contaminants trapped in the DE. The removed DE and the contaminants can be washed out the drain  195 . Removing and washing (blocks  590  and  595 ) the filter cartridges  135  can be accomplished by removing the top manifold  125 , lifting the filter cartridges  135  out of the bottom manifold  140 , and washing each filter cartridge  135  individually. The filter cartridges  135  can then be replaced (block  600 ) by placing the filter cartridges  135  into the bottom manifold  140  and placing the top manifold  125  on the filter cartridges  135 . 
     The bottom tank  170  and the lid  110  can also be washed out (block  605 ). After the filter cartridges  135 , the bottom tank  170 , and/or the lid  110  are sufficiently washed out, the lid  110  can be replaced onto the bottom tank  170 , the clamp  145  can be reattached, and the drain  195  can be closed (block  610 ). The DE filter  100  can then be restarted by following the process beginning at block  510  of  FIG. 5A . 
       FIG. 5D  illustrates a process for backwashing the DE filter  100  according to one embodiment of the invention. The backwash valve  220  (as shown in  FIG. 1 ) can be set (block  630 ) to a backwash position and the pump can be restarted (block  635 ). The backwash valve  220 , in the backwash position, can reverse the flow of water into the DE filter  100  (i.e., the water can be pumped into the outlet adapter  205  and can flow out of the inlet adapter  200 ). The backwash valve  220  can also include a backwash pipe (not shown) that can divert water coming from the DE filter  100  to a drain or sewer so that the contaminated water coming from the DE filter  100  does not flow into the swimming pool. The operator can let the backwash run for a period of time (e.g., ten minutes) (block  640 ) to allow the DE caked on the septum  320  and any contaminates contained in the DE to be washed off of the septum  320  and to flow out of the DE filter  100  through the backwash pipe. 
     The backwash sprayer  138  can be positioned between the air bleeder tube  130  and the air bleeder receiver  265  as shown in  FIG. 2B . During backwashing, the water flowing into the bottom manifold  140  can be forced into the backwash sprayer  138 . The water can exit the backwash sprayer  138  through jets positioned at opposing ends of the backwash sprayer  138 . The backwash sprayer  138  can include a check valve which can prevent water from flowing unfiltered through the jets and into the bottom manifold  140  during normal filtering. In some embodiments, the backwash sprayer  138  can be stationary. In other embodiments, the force of the water exiting the jets can cause the backwash sprayer  138  to rotate. The water exiting the jets of the backwash sprayer  138  can create turbulence in the bottom tank  170 . The turbulence in the bottom tank  170  can cause contaminants that have settled into the bottom tank  170  to become suspended in the water. The suspended contaminants can then be flushed out the backwash pipe. The turbulence caused by the backwash sprayer  138  can remove significantly greater contaminants from the DE filter  100  during backwashing and can result in a longer time period before another backwashing is required. As shown in  FIG. 5D , the operator can then stop the pump (block  645 ). The backwash valve  220  can be reset (block  650 ) to a normal operating position. The operator continues at block  510  by restarting the DE filter  100 , as shown in  FIG. 5A . 
     The backwash sprayer  138  can have any structure capable of generating turbulence in the bottom tank  170 . Embodiments of backwash sprayers can include jets on a bottom side of the bottom manifold  140 , a plurality of pulsating jets, a plurality of stationary jets, a plurality of rotating jets, a plurality of jets cycling forward and backward, one or more hoses having a free moving outlet positioned in the bottom tank  170 , a rotating or stationary circular head having a plurality of jets, and one or more rotating arms having one or more jets. 
     In some embodiments, a backwash brush or scraper can be positioned in the bottom tank and can have jets to rotate the backwash brush or scraper during a backwash. 
     In some embodiments, a backwash sprayer can be coupled to the outlet pipe  165 . In other embodiments, a backwash sprayer can be coupled to the bottom manifold  140 . Some embodiments can include more than one backwash sprayer and/or can include a plurality of backwash sprayers coupled to the outlet pipe  165 , the bottom manifold  140 , and/or the air bleeder tube  130 . 
     Various features and advantages of the invention are set forth in the following claims.