Abstract:
A water treatment system including a pair of water treatment tanks, each tank defining a flow path extending from a tank inlet to a tank outlet and containing a water treatment material disposed along the flow path for treating water as it travels from the inlet to the outlet. A system controller controls which of the tanks is on-line and which of the tanks is off-line and controls the regeneration of an exhausted tank. A multi-stage, spring-loaded control valve assembly controls the communication of fluid to a regeneration control turbine and includes a piston head and a relatively movable seat-carrying stem. A spring urges the stem away from the piston head such that initial movement of the head compresses the spring but does not produce movement in the seat. Sufficient movement of the piston head produces movement in the seat, thereby causing the seat to open pressure.

Description:
PRIORITY 
     The present invention claims priority to U.S. Provisional Application Ser. No. 61/346,221, filed May 19, 2010, the entirety of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to fluid treatment and in particular to an improved control system and control device for controlling a fluid treatment apparatus. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 4,298,025, which is owned by the present assignee, discloses a control valve for use in water softeners having two resin tanks. One of the resin tanks is normally on-line while the other tank is regenerated and placed in a standby condition until the first tank requires regeneration. The disclosed control valve controls which of the tanks is on-line and controls the regeneration sequence of an exhausted tank. 
     The quantity of water treated by a given tank, is monitored by a mechanism that includes a water usage turbine driven by water entering the on-line resin tank. When a predetermined quantity of water is treated, which produces a predetermined number of revolutions in the turbine, a regeneration sequence is initiated which places the standby tank on-line and isolates the exhausted tank. 
     A second turbine, operatively connected to a regeneration sequence control element (in the form of a disk) is rotated by a stream of water that is activated at the beginning of the regeneration cycle. The stream of water physically drives the regeneration control disk (via the turbine and associated drive train) through its sequence. With the disclosed arrangement, the frequency of regeneration of the water softener system is determined by the usage turbine which directly measures the quantity of fluid treated by a given tank. 
     SUMMARY OF THE INVENTION 
     The present invention provides a new and improved control valve for controlling a fluid treatment apparatus such as a deionization system or a water softener. In the illustrated embodiment, the improved control valve is used to control a fluid treatment system having a pair of resin tanks, one of which is on-line, while the other is regenerated and held in a standby condition. The disclosed control valve, although similar to the control valves described in U.S. Pat. Nos. 4,298,025 and 4,427,549, which are hereby incorporated by reference, includes several improvements which enhance the overall operation of a fluid treatment system that utilizes the control valve. 
     According to the invention, a water treatment apparatus is disclosed including at least one treatment tank containing a treatment material The tank defines a fluid flow path through which water to be treated is passed. The treatment tank may form part of a water softener, deionization unit or a mechanical filter. A control unit similar in construction to the control valve illustrated in U.S. Pat. Nos. 3,891,552 and 4,298,025 controls the communication of water to be treated (or a water source) with a tank inlet and controls the communication of treated water from a tank outlet and a conduit or system outlet. In the illustrated embodiment, the control unit also has a regeneration controller that controls the regeneration of the tank when needed. 
     According to the invention, a water treatment apparatus is disclosed and includes at least one water treatment tank defining a fluid flow path extending from the tank to a tank outlet; the treatment tank includes a water treatment media disposed in a flow path. A regeneration determining apparatus that includes a water driven turbine determines when the treatment media requires regeneration. According to the invention, regeneration is initiated by the opening of a control valve assembly embodying the present invention. The control valve assembly is spring loaded so that it provides a two-stage opening. The control valve includes a piston head that carries a peripheral seal, sealingly engaged with an associated bore. One end of a stem is slidably received within a piston bore and carries a seat at its other end which is sealingly engageable with a seat-sealing surface. The stem is urged in an axial direction away from the piston head, preferably by a coil spring, located in the piston head bore that acts between the end of the stem and the piston head. 
     According to the invention, the control valve assembly is opened by applying a signal pressure to the piston head which moves it in an opening direction. Initial movement of the piston head does not produce movement in the stem due to the coil spring acting between the stem and the piston head. During this initial movement of the piston head, the seat remains engaged with the associated sealing surface due to fluid pressure acting on the seat. Once the spring is compressed, further movement of the piston head moves the seat off the sealing surface. Once the seat is open even a small amount, the closing force on the seat is reduced and thereby allows the spring to move the seat away from the piston head. This results in further movement of the seat away from the sealing surface, thus fully opening the valve. 
     In accordance with a more preferred embodiment of the invention, the apparatus includes a second tank and the control unit is operative to control which of the tanks is on-line and which of the tanks is regenerated and then kept off-line until the on-line tank requires regeneration. 
     It has been found, that with the present invention, the apparatus can operate at lower source inlet pressures. In particular, in the past it was found that the control valve for establishing the communication of fluid pressure to the regeneration turbine could stall due to insufficient inlet pressure available to open the valve. In the past, attempts were made to alleviate this problem by reducing friction between the piston head seal and its associated bore. This involved tightening manufacturing tolerances with respect to the bore and the associated piston seal. The present invention allows the use of seals with increased friction, thereby reducing chances of leakage, etc., without comprising the ability of the control valve to open under lower inlet pressures. 
     A fuller understanding will be obtained and additional features of the invention will become apparent in reading the following detailed description made in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, in which: 
         FIG. 1  is a is a schematic representation of a water treatment system embodying the present invention; 
         FIG. 2A  is a perspective view of a regeneration control disc and associated port insert forming part of the present invention; 
         FIG. 2B  is a fragmentary, sectional view of a control valve shown schematically in  FIG. 1 ; 
         FIG. 3  is a top plan view of the control valve; 
         FIG. 4  is another fragmentary, sectional view of the control valve that is shown schematically in  FIG. 1 ; 
         FIG. 5  is a perspective view of a control valve component constructed in accordance with a preferred embodiment of the invention; 
         FIG. 6  is an exploded view of the control valve component shown in  FIG. 5 ; and 
         FIGS. 7-9  are fragmentary sectional views showing various operational positions of the control component shown in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates a water treatment system constructed in accordance with the preferred embodiment of the invention. The system includes a pair of resin tanks  10 ,  12  interconnected by a control valve module  14  that is similar to the control valves described in U.S. Pat. Nos. 4,298,025 and 3,891,552 which are hereby incorporated by reference. A source of regeneration solution indicated generally by the reference character  15  is connected to the valve  14 . 
     The control valve assembly  14  controls the communication of a source of water to be treated, indicated generally by the reference character  16  with the treatment tanks  10 ,  12 ; the communication of the tanks with an outlet indicated by the reference character  18 ; and, the regeneration of an exhausted tank. 
     The valve assembly  14  includes a plurality of water pressure operated valves, the opening and closing of which are controlled by a fluid signal control system. Whether the tanks  10 ,  12  are on-line or off-line is determined by a pair of inlet valves  70 ,  72  disposed in an inlet chamber  74  and a pair of outlet valves  76 , 78  disposed in an outlet chamber  80 . The inlet conduit  16  fluidly communicates with the inlet chamber  74 . The inlet valves  70 ,  72  control the communication between the inlet chamber  74  and respective tank inlet passages  82 ,  84 . Opening the valves  70 ,  72  allows feed water in the inlet conduit  16  to proceed into the tanks  10 ,  12 , respectively. 
     The valves  70 ,  72  are operatively connected to a piston  88 ,  90  disposed in chambers  92 ,  94 , respectively. The application of fluid pressures above the pistons apply valve closing forces to urge the valves  70 ,  72  into engagement with respective valve seats  70   a ,  72   a . The application of fluid pressure to the underside of the pistons exerts valve opening forces. 
     The outlet valves  76 ,  78  are similarly configured and include pistons  96 ,  98  disposed in chambers  100 ,  102 . The application of fluid pressure above and below the pistons  96 ,  98  applies valve closing and opening forces, respectively for moving the valves  76 , 78  towards and away from associated valve seats  76   a ,  78   a.    
     The valves  76 ,  78  control the communication between tank outlet passages  104 ,  106  of the tanks  10 ,  12 , respectively with the outlet chamber  80 . The outlet passages  104 ,  106  are connected to the top of the tanks  10 ,  12  and are in fluid communication with respective risers  107 ,  109 . The risers extend downwardly from the top of the tanks and open near the bottom of the respective tanks. In normal service, water to be treated is introduced at the top of the tank by an associated inlet passage  82 ,  84 . The water travels downwardly through a treatment media located in the tank and is discharged from the tank by way of the associated riser. In short, the treated water leaves from the bottom of the tanks  10 ,  12  and travels upwardly through the riser tubes  107 ,  109  and into the respective outlet passages  104 ,  106 . 
     When either of the valves are open, water flow from the associated tank is allowed to proceed to a water collection chamber  110  by way of a passage  112 . The collection chamber  110  communicates with the outlet conduit  18  through a fluid path that includes a passage  114  and an outlet chamber  116  that includes a rotatable turbine  116   a . As fully described in U.S. Pat. Nos. 3,891,552 and 4,298,025, the turbine is mechanically coupled to a usage monitoring disk  118  (shown in  FIGS. 2A and 2B ) which rotates as a function of the amount of water discharged through the outlet chamber  116  into the outlet conduit  18 . 
     Referring also to  FIGS. 2A and 2B , the usage monitoring disk  118  cooperates with a regeneration control disk  120 . The control disk rotates atop an annular insert  122  that defines a plurality of ports each communicating with an associated signal line. Signal lines a-k are illustrated in  FIG. 1 . Each line extends from the port insert  122  to one of a plurality of piston chambers. The control disk  120  sealingly engages the top surface of the insert  122  and includes structural formations that operate to communicate the ports formed in the insert  122  with either water supply pressure (supplied by a passage  124 ) or ambient pressure (by communicating the ports with one of two drain passages  126   a ), shown in  FIG. 2 . In  FIG. 1 , the drain passages  126   a  are represented by a single drain line designated as  126 . The ports and regeneration control disk  120  are arranged so that as the regeneration wheel  120  rotates, the valves are sequentially operated in order to cycle an exhausted tank through a regeneration cycle. 
     In addition to the valve elements described above, the control valve assembly  14  also includes a pair of drain valves  130 ,  132  for controlling the communication of the tank inlet passages  82 ,  84 , respectively, with a drain chamber  134  through respective branch passages  82   a ,  84   a . The drain chamber  134  communicates with ambient pressure drain through a drain conduit  135 . 
     The drain valves  130 ,  132  are operated by pistons  136 ,  138  disposed in respective piston chambers  150 ,  152 . In the preferred embodiment, the pistons are single acting and are driven to a valve open position by the application of fluid pressure to their top surfaces via signal lines a, b. When the fluid signals applied to the top piston surfaces is terminated, the drain valves  130 ,  132  are returned to their closed positions by a biasing force generated on the underside of the pistons by back pressure developed in the drain chamber  134 . The back pressure in the drain chamber  134  is developed due to a flow restrictor  139  disposed in the drain conduit. As the drain valves near their closed positions, fluid pressure in the conduits  82   a ,  84   a  apply additional force to the valve heads tending to fully close the valves and maintain their closure. In an alternate embodiment, biasing springs (not shown) bias the valves towards their closed positions illustrated in  FIG. 1  when the associated signal lines a, b are depressurized. 
     A regeneration control valve  140  constructed in accordance with the present invention controls the communication of water pressure from the water collection chamber  110  to a regeneration control turbine  142  located in a turbine chamber  143 . The valve  140  includes a single acting piston  500  disposed in a chamber  146 . The valve  140  is biased to its closed position by back pressure generated by a flow restrictor  149   a  disposed in a delivery passage  149  which controls the flow rate of water from the collection chamber  110  communicated through a passage  148 , when the valve  140  is opened. When the regeneration control valve  140  is opened (by the application of a fluid signal to the top surface of the piston by way of the signal line k) water pressure is allowed to proceed from the passage  148  to the passage  149  which includes a nozzle for directing water against the turbine  142 . The turbine  142  is mechanically coupled to the regeneration control disk  120  so that rotation of the turbine effects rotation of the control disk. 
     The application of fluid signals to the various piston chambers, as controlled by the relative movement of the regeneration control wheel with respect to the port insert  122 , determines the sequence of valve actuation. The control disk  120  selectively communicates either water pressure from the collection chamber (fed to the disk by the pressure line  124 ) or the ambient drain pressure via the passage  126  (which communicates with the drain ports  126   a  shown in  FIG. 2A ), to the various signal lines. 
     The regeneration components include a regeneration fluid aspirator  260  disposed in the collection chamber  110 . The aspirator comprises a fluid flow regulating element  264  and a venturi  260   a . The outlet of the venturi communicates with the tank outlet passages  104 ,  106  through branch passages  104   a ,  106   a  that include check valves  280 ,  282 . The throat of the venturi communicates with the source of regeneration solution  15 . 
     When either of the drain valves  130 ,  132  are opened (and the respective inlet and outlet valves are both closed), water in the collection chamber  110  is allowed to proceed through the venturi  260   a  and into the tank being regenerated. For example, suppose the drain valve  130  is opened. Water from the collection chamber will flow through the venturi  260   a  into the outlet passage  104  of the tank  10  (via passage  104   a ). The water will then travel through the tank assembly  10  in a counterflow direction and be ultimately discharged to the ambient drain by way of the inlet passage  82 , the branch passage  82   a  and the drain chamber  134 . As water passes through the venturi, regeneration fluid is drawn from the regeneration source  15  through a supply conduit  220  and mixed or “aspirated” with the venturi fluid. The regeneration fluid (now diluted with treated water) passes through the tank being regenerated. The effluent from the tank is discharged to drain via the drain chamber  134 . 
     The sequence of regeneration steps as well as the frequency of regeneration is controlled by the regeneration control disk  120  and the usage disk  118 , respectively. Referring to  FIGS. 1, 2A and 2B , the regeneration control disk  120  sealingly engages and rotates atop the circular port-defining insert  122 . The ports defined by the insert  122  communicate with the various piston chambers. The underside of the regeneration control disk  120  includes a depending wall  248  that divides the underside of the disk  120  into pressurized and drain regions  249 ,  251 . The port insert  122  includes a pair of drain apertures  126   a  located on either side of an upwardly extending stub shaft  250  about which both the regeneration control disk  120  and the water usage disk  118  rotate. The drain apertures  126   a  communicate with the drain chamber  134  through the passage  126  (shown in  FIG. 1 ) which is integrally formed in the valve body. Thus, the drain region of the regeneration control disk is maintained at the ambient drain pressure. 
     Two sets of ports are provided in the insert  122  and are located symmetrically about an imaginary diametral line  268 . The ports to the left of the line  268  control the regeneration sequence for the tank  10  whereas the ports to the right of the line  268  control the regeneration sequence for the tank  12 . During a regeneration cycle, the control disk  120  rotates 180° to effect the complete regeneration cycle of one of the tanks. The location of the ports and their function, as shown in  FIG. 2  correspond to the ports shown and described in U.S. Pat. Nos. 3,891,552 and 4,298,025. As fully explained in these earlier patents, the depending wall  248  controls the communication of pressurized water from the pressurized region  249  to the ports or communicates the ports with the drain region  251  to depressurize the respective chambers. The inlet and outlet valves  70 ,  72 ,  76  and  78  each include a “top” and a “bottom” port. The “top” ports communicate with the top of the associated operating pistons  88 ,  90 ,  96 ,  98  and the pressurization of these ports apply a valve closing force. Conversely, the “bottom” ports communicate with the underside of the pistons and apply valve opening forces when pressurized. 
     To facilitate the explanation, the ports shown in  FIG. 2A  will use the same reference characters as those used for the valves with which they communicate. If a given valve has both an upper and lower port, the upper port will be designated by the same reference character that is used for the valve it controls, followed by a single apostrophe. The bottom port for that valve will be designated by the same reference character followed by a double apostrophe. For valves that only require a single port, i.e., the drain valves  130 ,  132 , the port will be designated by the same reference character that is used for the valve. As an example, the port marked  70 ′ communicates with the region above the piston  88  of the intake valve  70  via signal line f. The port marked  70 ″ communicates with the underside of the piston  88  of the valve  70  via signal line e. The port marked  130  communicates with the drain valve  130  via the signal line b. 
     Usage disk  118  and the regeneration control disk  120  are preferably rotated by a drive mechanism fully disclosed in U.S. Pat. No. 4,298,025. Referring to both  FIGS. 1 and 2 , the disks  118 ,  120  are driven by a ratcheting mechanism that includes a plurality of pawls. As seen best in  FIG. 2 , the usage disk  118  rotates atop and concentrically with the regeneration control disk  120 . The disks  118 ,  120  each include peripheral ratchet teeth  118   a ,  120   a  respectively. The water usage disk  118  is rotated by a pawl arrangement indicated generally by the reference character  270 . Both discs rotate in the direction indicated by the arrow  271 ; an anti-reverse pawl  272  prevents reverse rotation of the disk  118 . 
     The pawl arrangement  270  includes a pair of individual, spring biased pawls  274 ,  276 , concentrically journalled on an eccentric shaft  278 . The shaft  278  is coupled to the water usage turbine  118   a  through a reduction gear train  283  (shown in  FIG. 4 ). In operation, the usage turbine  116   a  shown in  FIG. 1 , and hence the water usage disk  118  rotates in proportion to the amount of treated water discharged by the valve assembly  14 . 
     The usage disk  118  also includes an axially depending flange  279  that is interrupted by a plurality of circumferentially spaced slots  279   a.    
     The number and position of the slots  279   a  determine the frequency of regeneration. The lower pawl  274  of the ratchet mechanism  270  includes a prong  274   a  that extends into sliding engagement with the flange  279 . The prong  274   a  is sized so that when in engagement with the flange, the pawl  274  is maintained out of engagement with the regeneration control disk  120 . When the prong  274   a  enters one of the slots  279   a , the pawl  274  engages the ratchet teeth  120   a  of the regeneration control disk  120  so that rotation of the eccentric shaft  278  causes concurrent rotation in the disks  118 ,  120 . The initial rotation of the regeneration control disk  120  by the lower pawl  274  causes one of the control valve ports in the port insert  122  to be pressurized by virtue of being uncovered by a depending surface  281 , thus initiating regeneration. 
     When the control valve  140  (shown in  FIG. 1 ) is open, a fluid stream is directed to the regeneration turbine  142  (shown in  FIG. 1 ) located in the turbine chamber  143 . The turbine  142  is mechanically coupled to a regeneration drive pawl  284  through a reduction gear train  285  (shown in  FIG. 4 ). The pawl is journalled on an eccentric shaft  286 . Rotation of the turbine  142  thus effects incremental rotation of the regeneration control disk  120  and in so doing, effects a regeneration cycle. The regeneration cycle continues until the control port communicating with the control valve chamber  146  via signal line K (shown in  FIG. 1 ) is depressurized thus closing the control valve  140 . 
     During the regeneration cycle, treated water is communicated to the venturi  260   a . The flow of water through the venturi draws regeneration solution from the regeneration source  15  via conduit  220 . 
     In a water softening application, the regeneration source  15  typically includes a brine well and brine control valve (not shown). When a predetermined amount of regeneration solution is drawn from the source  15 , the brine valve (not shown) closes. The flow of treated water (in this example softened water continues to flow into the regenerated tank for a predetermined amount of time to effect a counterflow rinse. After a predetermined amount of time, the flow of softened water into the tank being regenerated is terminated by depressurizing the appropriate drain piston chamber  150 ,  152 . 
     Referring in particular to  FIGS. 1-4 , the process steps will now be discussed in greater detail. As indicated above, a regeneration cycle is initiated when the depending surface  281  uncovers one of the ports communicating with the control valve  140 . As seen in  FIG. 2A , two control valve ports, separated by 180°, are defined in the insert  122 . It should be apparent, the regeneration control disk  120  rotates through an arc of 180° during a regeneration cycle. For purposes of explanation, suppose that tank  10  requires regeneration. As indicated in  FIG. 2A , the ports, defined in the insert  122 , to the left of the diametral line  268 , control the regeneration of tank  10 . Movement of the regeneration control disk  120  is initiated by the pawl assembly  270  as explained above. The initial movement in the disk  120  by the pawl  270  causes the depending surface  281  to uncover the control valve port  140 . 
     According to the invention, the control valve  140  is of a two-piece, spring loaded design. The control valve of the prior art was of a single piece construction and it was found, that under certain operating conditions, movement of the control valve downwardly (as viewed in  FIG. 1 ) could stall and, as a result, the control valve would not fully open. It is important that the control valve  140  fully open in order to reduce the possibility of having resin fines or other particulate matter getting caught between the seal and associated seat which would prevent complete closure of the control valve and result in wasted water. 
     Referring to  FIGS. 4-9 , the construction of the control valve assembly  140  is illustrated. The improved control valve  140  includes a piston head  500  that mounts a seal  504  which may be a quad ring. A stem  506  is secured to the piston head  502 . In the preferred embodiment, the stem  506  is inserted into a keyed bore  510  formed in the piston head  500  and is turned through a predetermined angle, i.e., a quarter turn in order to lock the stem to the piston head. As seen best in  FIG. 6 , the stem  506  includes a pair of laterally extending lugs  508  which are received by associated key ways formed in the bore  510 . Eventually, the stem can be rotated a quarter turn so that the lugs  508  are captured in associated slots  509  formed in the piston head  500 . The slots  509  have clearance in the axial direction that determine how much relative movement is permitted between the stem  506  and the piston head  500 . 
     A compression spring  512  is captured in the bore  510  between the top of the stem  506  and the piston head  500  and urges the piston head and stem apart. The lower end of the stem receives a cone-shaped seat  516  and is snapped onto the lower end of the stem  506 . A barb  518  locks the seat to the stem  506 . 
     Referring, in particular, to  FIGS. 7-9 , the operation of the improved control valve assembly  140  is illustrated. When the control valve  140  is to be opened, a pressure signal via signal line K (see  FIG. 1 ) is applied to the top of the piston head  500 . The force generated by the signal pressure in the signal line K, urges the piston downwardly against the force of the spring  512  until it moves to the position shown in  FIG. 8 . During this initial motion, the piston  500  moves relative to the stem  506  and, in effect, the valve remains closed, i.e., the seat  516  remains in contact with its associated seating surface  520  because pressure in a chamber  522  urges the seat into contact with the associated seating surface  520 , as seen in  FIG. 4 . Further movement of the piston head, due to the pressure in signal line K, ultimately urges the piston head  500  downwardly, causing the seat  516  to disengage the seating surface  520 , thereby allowing the flow of water from the chamber  522  into the passage  149  (see  FIG. 1 ). The pressure tending to close the seat  516  is relieved once the seat  516  disengages its seating surface  520  and, thus, the spring urges the stem  506  to move downwardly with respect to the piston head  500 , thus causing further separation of the seat  516  from its seating surface  520  and, in effect, creating a much larger opening between the seat  516  and the seating surface  520 . 
     At the conclusion of regeneration cycle, the signal line K is depressurized and fluid pressure on the underside of the piston moves the piston head upwardly, thereby causing the seat  516  to re-engage its seating surface  520 . This two-stage opening ensures maximum opening of the control valve  140  and reduces the need for tight manufacturing tolerances for the sealing ring  504  and bore  510  in which the piston head  500  is slidably received. Past efforts to improve the operation of the control valve  140  in water treatment applications where low source pressure was present, included carefully controlling the amount of “squeeze” of the sealing ring  104  in order to minimize or lower seal friction between the piston head  500  and the bore  510 . At times, this resulted in leakage past the seal ring  504 . With the present invention, a reliable opening of the control valve assembly  140  is achieved even in fluid treatment applications where low source pressures are encountered. With the present invention, the “squeeze” of the sealing ring  504  can be increased, while still insuring that the seat  516  moves to a fully open position. 
     The water treatment unit then goes through several process steps to complete the regeneration cycle. Initially the regeneration solution is passed through the tank being regenerated in a counter-flow direction. This is followed by a slow rinse which is also in the counter-flow direction. More specifically, in the slow rinse step, treated water (i.e. softened water if the unit is a water softener) from the collection chamber  110  is injected into the outlet of the tank being regenerated, travels down the associated riser tube  107  or  109  and then is discharged through the inlet conduit into the drain chamber. Full details of this step of the regeneration process can be found in U.S. Pat. Nos. 4,298,025 and 3,819,522. 
     A full downflow rinse step only follow the counter-flow rinse step, if desired. The down flow rinse step conveys water through the regenerated tank in a service direction. This step flushes any remaining regeneratant out of the tank while at the same time tending to pack the bed in preparation for placing the tank in service. 
     To achieve this step, if desired, a pair of purge valves  400 ,  402  are provided in the control valve  14 . The purge valves control the fluid communication between the outlets of the tanks  10 ,  12  and an ambient drain. More specifically, to effect a downflow rinse of a tank, its associated intake valve is opened, its outlet valve is closed and its associated purge valve is opened. With this valve relationship, source water is communicated to the inlet chamber  74 , proceeds into the tank, passes through the water treatment media, and is ultimately discharged from the tank through the associated riser tube. The discharged water is conveyed to drain through an open purge valve associated with the tank. A full discussion of these purge valves and associated components can be found in U.S. Pat. No. 6,214,214, which is hereby incorporated by reference. 
     The logic and hydraulics for opening and closing the purge valves  400 ,  402  are obtained from fluid signals being sent to the inlet and outlet valves. For purposes of an explanation suppose that tank  12  is the one being regenerated. 
     From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications.