Abstract:
An apparatus for positive water retention and circulation in single entrance pipe water storage tanks having an arrangement of directional flow check valves coupled to allow injection of water entering the tank at a different level than water exiting the tank. In a preferred embodiment water enters the tank at a higher level than water leaving the tank. The arrangement minimizes thermostratification within the tank in warmer months and further helps to minimize surface ice buildup in colder months.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates in general to water circulation systems for potable water storage tanks and more particularly, to an apparatus for use with single pipe water storage tanks which minimizes thermostratifying and further promotes water circulation with a positive retention time. 
     With many conventional potable water storage tanks as used in a typical city or county water supply, a single pipe is used to fill and drain the water within. Typically, this single pipe injects and removes water from the base of the storage tank. In such a system, the water which enters the tank is usually the water which exits immediately thereafter when a supply of water is needed by the community. This means that there is little if any retention time for water which is injected into the tank. This is especially true in warmer months when the water which enters is often colder than the water within the tank and therefore tends to remain at the lowest portion of the tank. Thus, water which is removed is typically the same water which immediately theretofore entered. This form of water removal precludes thorough mixing with or depletion of water which was at the upper portions of the storage tank. Without a through mixing of inlet and outlet water, the tank tends to thermostratify. This means that the water has a temperature gradient within the tank. The colder portions of said gradient tend to induce sweating on the outside of said storage tank and thereby cause said tank to externally deteriorate. That is, since the tanks are typically manufactured of an external ferrous metal material, said material oxidizes or its exterior coating deteriorates due to the sweated moisture present on its exterior surface. Furthermore, in chlorinated water supply systems, the lack of thorough mixing within a single pipe system denies any injected chlorine the time to circulate and mix with the water within the storage tank. This may cause excessively low or high concentrations of chlorine in the municipal water supply. 
     In the colder months, ice will typically form on the top surface of the water held in a storage tank. The greater the ice buildup, the greater the potential for damage to the interior protective coating of the storage tank. Thus, a city or county water supplier has a vested interest in minimizing surface ice buildup. In the winter months, water which enters the tank from the base is typically warmer than the surrounding water. Unfortunately, with a conventional single pipe system, the inlet water is unable to reach the top surface of the storage water without diffusing and cooling with the water stored within the tank. Thus, the potential for inlet water minimizing surface freezing within the tank is not utilized. 
     Prior to the art of the present invention, the only solution for solving the thermostratification problem in a single pipe system has been the incorporation of a separate inlet and outlet pipes. That is, the inlet pipe functions only as a conduit for inlet water and a second pipe of sufficient fire flow diameter is added to provide outlet flow at the base of the water storage tank. This modification is quite costly and time consuming. 
     Accordingly, it is an object of the present invention to provide an apparatus for positive water retention and circulation in storage tanks which injects inlet water at a higher level within the storage tank and removes water from a lower level within the tank thereby promoting a positive retention time of injected water. 
     Another object of the present invention is to provide an apparatus for positive water retention and circulation in storage tanks which is easily adaptable to a conventional single pipe potable water storage tank. 
     A further object of the present invention is to provide an apparatus for positive water retention and circulation in storage tanks which minimizes thermostratification within the storage tank and also provides for a thorough mixing of inlet and outlet water. 
     A still further object of the present invention is to provide an apparatus for positive water retention and circulation in storage tanks which is able to minimize ice buildup on the surface of the stored water during winter months. 
     SUMMARY OF THE INVENTION 
     To accomplish the foregoing and other objects of this invention there is provided an apparatus for positive water retention and circulation in storage tanks in conjunction with a single pipe potable water storage tank. In a preferred embodiment, the apparatus comprises two or more directional flow control check valves which mate onto and with the entrance or inlet pipe for a single pipe water storage tank, and an extension pipe for directing the inlet water near or above the top surface of the stored water. Said flow control check valves are typically one way flapper valves, but may comprise other types of directional valves which allow water flow in only one direction. 
     In a single pipe water storage tank, the water enters and exits through a pipe at the base of the tank. The present art apparatus in preferred and alternative embodiment forms, fits onto the single entrance pipe and directs water entering the tank through the extension pipe and water leaving the tank through the one or more exiting flow control check valves near the base. This arrangement creates water inflow to the upper portions of the tank and water removal from the lower portions of the tank. A preferred embodiment will utilize two directional flow control check valves near the base of the tank for exiting water and one check valve within or below the extension pipe which allows water to enter the upper portions of the tank. Alternative embodiments may remove the inlet directional flow control valve and place the extension pipe above the surface of the water. Further alternative embodiments may utilize more or less than two directional flow control check valves for exiting water. 
     In a preferred embodiment, a pipe coupler having four ports, two substantially horizontal and two substantially vertical, is placed onto the potable water storage tank entrance pipe. The entrance pipe is coupled to the lower most substantially vertical port of said coupler. Onto the upper most substantially vertical port is coupled an extension pipe and an inlet flow control check valve. Onto each of the substantially horizontal ports is coupled an exiting flow control check valve. Each flow control check valve allows water to flow in only one direction, thus proper direction placement is critical. Since said pipe coupler is located near the base of the water storage tank, said exiting flow control check valves are able to ensure that only water from the base ofthe tank exits when a demand is placed upon the water tank. All entering water is transferred near or above the surface of the water level by the extension pipe. An alternative embodiment may incorporate a pipe coupler having only three ports, thereby providing only one exiting flow control check valve near the base of the tank. Further alternative embodiments may incorporate a pipe coupler having a plurality of ports together with a plurality of check valves. All embodiments incorporate exiting flow control check valves which in combination are of sufficient size to allow fill fire flow capacity as required by the community serviced. 
     The present art may be adapted for elevated leg water storage tanks having a wet riser as shown in Figure two or ground storage tanks having a water column extending to ground level as shown in Figure one. A wet riser is a term of art which describes a pipe connected around the entrance of inlet pipe and of substantially larger diameter. The wet riser forms a water column of typically three (3) feet or larger size around the inlet pipe and couples with the storage tank. This wet riser pipe typically mates and connects with the base of the elevated water storage tank and extends downward to ground level. With the art of the present invention, water is removed from the base of the wet riser or water column near ground level. That is, the exiting flow control check valves are placed within ports on the inlet or entrance pipe near the wet riser or water column base near ground level. The inlet flow control valve is placed and functions as aforementioned. Alternative embodiments may incorporate more than one inlet flow control check valve. This concept of having a water column extending to ground level and placing the exiting flow control check valves near said ground level is shown in Figures one and two of the present application. 
     The apparatus of the present art may be manufactured of many types of materials including but not limited to plastic, rubber, metal, composites, ceramic or any other material which may direct and control the flow of water. The apparatus of the present art may further be used with liquids other than water when positive retention is required. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Numerous other objects, features and advantages of the invention should now become apparent upon a reading of the following detailed description taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a plan view of an apparatus for positive water retention and circulation in storage tanks together with and positioned within a ground storage tank shown in phantom; 
     FIG. 2 is a plan view of an apparatus for positive water retention and circulation in storage tanks together with and positioned within an elevated leg tank with a wet riser shown in phantom; 
     FIG. 3 is a plan view of an apparatus for positive water retention and circulation in storage tanks standing alone. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, there is shown in FIGS. 1-3 an apparatus for positive water retention and circulation in storage tanks together with the entrance pipe and storage tanks of FIGS. 1-2. The apparatus for positive water retention and circulation in storage tanks  10  is particularly adapted for use with single entrance pipe potable water storage tanks without installation of a second entrance or exit pipe. 
     The drawings show the apparatus for positive water retention and circulation in storage tanks  10  in conjunction with said storage tanks comprising one or more inlet flow control check valves  12 , one or more exiting flow control check valves  14 , one or more extension pipes  16 , an entrance pipe  18 , and a pipe coupler  20 . Alternative embodiments may forego the use of the inlet flow control check valve  12  provided that the extension pipe  16  is placed above the water level within the tank. 
     A conventional single pipe water storage tank or reservoir has a single entrance pipe  18  which provides inlet and outlet (exiting) water flow to the tank. That is, the municipal water mains are connected directly with the entrance pipe  18  and the municipal water pump system. The preferred embodiment of the present invention in conjunction with said single pipe water storage tank places and secures a pipe coupler  20  onto said entrance pipe  18 . In a preferred embodiment, the pipe coupler has four ports, one for connection to the entrance pipe  18 , one for connection to the inlet flow control check valve  12  and extension pipe  16  combination, and two for connection with two exiting flow control check valves  14 . Each component is typically secured with and onto the pipe coupler  20  with bolts. Alternative embodiments may secure each component with welds, glue, solvents, threads, pins, press fits or any other bonding mechanism which is able to withstand the pressure and flow of the water within the pipe coupler  20 . Alternative embodiments may also have more or less than two ports on the pipe coupler  20  for connection with the exiting flow control check valve(s)  14 . Further alternative embodiments may include more than one port for connection with the inlet flow control check valve  12  and extension pipe  16  combination. 
     The inlet flow control check valve  12  and extension pipe  16  combination is attached to the pipe coupler  20  in such a fashion as to allow inlet water flow toward the topmost portions of the water storage tank. In a preferred embodiment, the inlet flow control check valve  12  is placed onto and immediately after the pipe coupler  20  and the extension pipe  16  is connected to the outlet port of the inlet flow control check valve  12  in such a fashion as to direct water to the upper portions of the water storage tank. Alternative embodiments may place the inlet flow control check valve  12  after or within the extension pipe  16  and fulfill the expectations of the present art. No geometric limitations are placed on the shape of the inlet flow control check valve  12  or extension pipe  16 . That is, they need not be straight or curved, provided that the combination allows water to enter near the top portions of the tank. An alternative embodiment may forego use of the inlet flow control check valve  12  and place the extension pipe  16  directly onto the pipe coupler  20 . In such an alternative embodiment, the extension pipe  18  is typically placed such that water enters above the water surface level and thereby cannot exit the extension pipe  18 . 
     In a preferred embodiment, two exiting flow control check valves  14  are placed onto the pipe coupler  20  near the entrance pipe  18 . In all embodiments, the exiting flow control check valve  14  is placed near the base of the water storage tank or at the base of the wet riser as shown in FIG. 2 or at the base of the water column as shown in FIG.  1 . This placement ensures that water exiting the tank will be drawn from the base of the tank or from near ground level as depicted in FIGS. 1 &amp; 2. The directional flow placement of said valves  14  allows water only to flow in an exiting direction through said pipe coupler  20  and into said entrance pipe  18 . Typically, the exiting flow control check valves  14  in combination are of sufficient size to allow full fire flow capacity to the community served. Again, said flow control check valves  12 ,  14  are typically one way flapper valves, but may comprise other types of directional valves which allow water flow in only one direction. 
     In operation, the municipal water supply pump injects water into the entrance pipe  18  and through the pipe coupler  20 , the inlet flow control check valve  12 , and the extension pipe  16 . This places the inlet water substantially above the base of the storage tank depending upon the height of the extension pipe  16 . Water is unable to flow into the base of the tank through the exiting flow control check valves  14  due to the fact that said directional valves  14  are automatically locked closed during inlet water pressurization. When a supply of water is required from the water storage tank, water begins to flow out of the entrance pipe  18  and is only able to be supplied from water flowing through the exiting flow control check valve(s)  14 , again due to the directional flow of the inlet flow control check valve  12 . That is, the inlet flow control check valve  12  is placed such that it will not allow water to flow out of the tank, whereas the exiting flow control check valve(s)  14  is placed such that it will allow water to flow out of the base of the tank, through the pipe coupler  20  and into the entrance pipe  18 . Should an alternative embodiment be used which does not utilize an inlet flow control check valve  12 , water enters through the extension pipe  16  which is above the water surface level and obviously cannot exit said pipe  16  since the water level is below point of entrance. 
     From the foregoing description, those skilled in the art will appreciate that all objects of the present invention are realized. An apparatus for positive water retention and circulation in storage tanks together with the entrance pipe and storage tanks has been shown and described. The device of this invention is able to provide inlet water to a storage tank through a single pipe and ensure that water entering said tank is placed at a higher elevation than water exiting, thereby ensuring a positive retention time and thorough mixing. 
     Having described the invention in detail, those skilled in the art will appreciate that modifications may be made of the invention without departing from its spirit. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described. Rather it is intended that the scope of this invention be determined by the appended claims and their equivalents.