Abstract:
A fluid content monitor including a cuvette, a calorimeter adapted to generate a signal indicative of contents of a fluid sample contained in the cuvette, a container for holding a reagent, and a pump assembly for delivering reagent from the container to the cuvette. The pump assembly includes a tube extending from the container to the cuvette, check valves preventing reverse flow in the tube, and a hammer driven by a solenoid for repetitively compressing the tube to pump reagent to the cuvette. The cuvette can be removed for cleaning and replacement.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Patent Application No. 60/758,799, filed Jan. 13, 2006, which is incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to a fluid content monitor that can be used, for example, to monitor the residual chlorine level in drinking water, irrigation water, wastewater, and the like. 
     BACKGROUND OF THE RELATED ART 
     Various feed, dosing and metering pumps are known for delivering chemical additives to a supply of water or other liquid. Such pumps are particularly useful in fluid content monitors for adding reagents to test drinking, wastewater, and industrial water supplies for the presence of residual chlorine and other constituents. Conventionally, such monitoring has been performed using calorimetric reagent technology wherein a chemical reagent, such as DPD (N,N-diethyl-p-phenylenediamine), is dispensed into a test sample of water contained in a cuvette. The sample turns a certain hue, which depends upon the concentration of the chlorine in the water. This concentration is then photometrically determined by analyzing the hue with an appropriate electronic tester. 
     In order to obtain accurate test results, precisely measured amounts of reagent must be added to the test sample. Preferably, the reagents include an indicator chemical, such as DPD, and a buffer for adjusting the PH of the test sample. If the amounts of these reagents are not accurately controlled, erroneous measurements are likely to be taken. A dirty or damaged cuvette can also cause erroneous measurements. 
     What is still desired is a new and improved fluid content monitor that reliably and automatically delivers precisely measured doses of reagents to a water sample so that the sample may be accurately tested for the presence of selected constituent elements such as chlorine. 
     SUMMARY OF THE DISCLOSURE 
     Exemplary embodiments of the present disclosure provide a fluid content monitor including a chemical metering pump assembly that reliably and automatically delivers precisely measured doses of reagents to a water sample so that the sample may be accurately tested for the presence of selected constituent elements such as chlorine. The present disclosure also provides a fluid content monitor including a cuvette that can be easily removed without tools for cleaning or replacement. 
     In one embodiment, the fluid content monitor includes a cuvette, a calorimeter adapted to generate a signal indicative of contents of a fluid sample contained in the cuvette, a container for holding a reagent, and a pump assembly for delivering reagent from the container to the cuvette. The pump assembly includes a tube extending from the container to the cuvette, check valves preventing reverse flow in the tube, and a hammer driven by a solenoid for repetitively compressing the tube to pump reagent to the cuvette. 
     In another embodiment, the fluid content monitor includes a light transparent cuvette adapted to receive a fluid sample, a calorimeter adapted to direct light through the cuvette, receive the light passing through the cuvette, and generate a signal indicative of contents of the fluid sample based upon the received light, a container for holding a reagent and a pump assembly. Preferably, the pump assemble includes a body having a side wall extending from an end wall to define a chamber, and openings in the side wall adjacent the end wall, a hammer mounted within the chamber of the body for reciprocating linear movement between a retracted position moved away from the end wall and an extended position moved against the end wall, an actuator operatively connected to the hammer, a reagent tube extends from the container for delivering reagent to the cuvette, wherein a resiliently flexible section of the tube passes through the openings in the side wall of the pump body and extends through the chamber between the hammer and the end wall such that the resiliently flexible section is open when the hammer is in the retracted position and substantially closed when the hammer is in the extended position. In a further aspect, an inlet check valve is carried by the reagent tube between the reagent container and the pump to prevent reverse flow to the reagent container, and an outlet check valve is carried by the reagent tube between the pump and the cuvette to prevent reverse flow to the pump. 
     In another embodiment, the fluid content monitor includes a light transparent cuvette adapted to receive a fluid sample, a container for holding a reagent, a pump adapted to pump reagent from the reagent container to the cuvette and a colorimeter adapted to direct light through the cuvette, receive the light passing through the cuvette, and generate a signal indicative of contents of the fluid sample based upon the received light. The colorimeter preferably includes a body defining a cuvette portal for removably receiving the cuvette, and a passageway extending through the cuvette portal, and a nozzle removably secured in the passageway, wherein the nozzle is adapted to lock the cuvette in the passageway. 
     In still another embodiment, the fluid content monitor includes a light transparent cuvette adapted to receive a fluid sample, a nozzle connected to the cuvette for introducing reagent into the cuvette, a colorimeter adapted to direct light through the cuvette, receive the light passing through the cuvette, and generate a signal indicative of contents of the fluid sample based upon the received light, a first container for holding a first reagent, a second container for holding a second reagent and a pump assembly. The pump assembly includes a body having a side wall extending from an end wall to define a chamber, and openings in the side wall adjacent the end wall, a hammer mounted within the chamber of the body for reciprocating linear movement between a retracted position moved away from the end wall and an extended position moved against the end wall, an actuator operatively connected to the hammer, a first reagent tube is in fluid communication with the first container for delivering reagent to the cuvette, wherein a resiliently flexible section of the first reagent tube passes through the openings in the side wall of the pump body such that the respective resiliently flexible section is open when the hammer is in the retracted position and substantially closed when the hammer is in the extended position, a second reagent tube is in fluid communication with the second container for delivering reagent to the cuvette, wherein a resiliently flexible section of the second reagent tube passes through the openings in the side wall of the pump body such that the respective resiliently flexible section is open when the hammer is in the retracted position and substantially closed when the hammer is in the extended position, and an inlet check valve carried by the each reagent tube between the respective reagent container and the pump to prevent reverse flow to the reagent containers. 
     Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only an exemplary embodiment of the present disclosure is shown and described, simply by way of illustration of the best mode contemplated for carrying out the present disclosure. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference is made to the attached drawings, wherein elements having the same reference character designations represent like elements throughout, and wherein: 
         FIG. 1  is a front elevation view of an exemplary embodiment of a fluid content monitor constructed in accordance with the present disclosure, and which can be used, for example, to monitor the residual chlorine level in water; 
         FIG. 2  is a front perspective view of the chlorine monitor of  FIG. 1  shown with a cover removed to illustrate a pump assembly providing fluid connections between chemical reagent containers and a cuvette in a colorimeter; 
         FIG. 3  is a front elevation view of the chlorine monitor of  FIG. 1  shown with the cover and chemical reagent supplies removed; 
         FIG. 4  is an front perspective view of the pump assembly and the colorimeter of the chlorine monitor of  FIG. 1 ; 
         FIG. 5  is a rear perspective view of the pump assembly including a pump, a pump actuator, tubing, check valves, and a mounting bracket; 
         FIG. 6  is an exploded rear perspective view of the pump assembly minus the mounting bracket; 
         FIG. 7  is an enlarged cross-sectional view of the pump, the pump actuator, and the tubing, wherein a hammer of the pump is shown in a retracted position; 
         FIG. 8  is an enlarged cross-sectional view of the pump, the pump actuator, and the tubing, wherein the hammer is shown in an extended position compressing the tubing; 
         FIG. 9  is a front perspective view of the calorimeter, wherein the cuvette and a nozzle are shown removed from a body of the calorimeter; 
         FIG. 10  is an exploded front perspective view of the colorimeter; and 
         FIG. 11  is a sectional view of the colorimeter. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Referring first to  FIGS. 1-3 , an exemplary embodiment of a fluid content monitor  10  constructed in accordance with the present disclosure is shown. The monitor  10  can be used, for example, to measure residual free or total chlorine levels in water. The monitor  10  is equally well-suited for other chemical or industrial processes but is described herein with respect to chlorine monitoring using calorimetric DPD (N,N-diethyl-p-phenylenediamine) chemistry. 
     The residual chlorine monitor  10  includes a strong, shatterproof case  12  with a removable front cover  14 . The case  12  is also small in size relative to prior art monitors and corrosion-resistant to provide simple installation in a wide array of locations. As shown in  FIG. 1 , the front cover  14  defines a window  16  to allow operator monitoring and control. The window  16  provides access to a control panel  18  having touch pad controls  20  and a display panel  22 . The viewing window  16  also allows inspection of a test sample holder or cuvette  30  that contains the fluid being tested. 
     Referring to  FIG. 2 , the residual chlorine monitor  10  is shown with the cover removed and removable first and second containers  40   a ,  40   b  for chemical reagents secured within the case  12 , while in  FIG. 3  the monitor  10  is shown with the containers removed. As shown in  FIGS. 2 and 3 , the monitor  10  includes a colorimeter  100  that receives the sample cuvette  30 , and a pump assembly  200  for transferring the reagents from the reagent containers  402 ,  40   b  to the cuvette  30 . As described in greater detail below, the cuvette  30  is removably mounted within the colorimeter  100  to allow for periodic cleaning or replacement. The calorimeter  100  measures the concentration of a known constituent, e.g., chlorine, of a solution by comparison with colors of standard solutions of that constituent. 
     Referring to  FIGS. 2 and 3 , the chlorine monitor  10  includes an inlet line  60  for receiving a water sample to be tested, and a pressure regulator  62  and inlet valve  64  for controlling flow of the water sample to the cuvette  30  for testing. A drain valve  70  controls flow from the cuvette  30  to a drain line  72  after testing has been completed. According to one exemplary embodiment, both the inlet valve  64  and the drain valve  70  are solenoid-actuated valves. 
     Electrical power is provided to the chlorine monitor  10  and to the various electrical and electronic components thereof through a connector  80  that extends through the case  12  as shown in  FIGS. 1-3 . In the exemplary embodiment shown, a second connector  82  allows the monitor  10  to be attached to one or more alarms (not shown), which are activated when the test results fall outside of predetermined parameters. A third connector  84  allows for on-line communication between the monitor  10  and a remote location. 
     Although not viewable in the drawings, the chlorine monitor  10  also includes an electronic controller (i.e., computer processor) that is operatively connected to the various components of the monitor  10 . The controller is programmed to control: delivery of the water sample to the cuvette  30  using the water inlet valve  64 ; delivery of the reagents to the cuvette  30  using the pump assembly  200 , testing of the sample using the calorimeter  100 ; and draining of the sample from the cuvette  30  after testing using a water drain valve  70 . Signals representing photometric measurements provided by the calorimeter  100  are processed by the electronic controller, which then displays the results on the display panel  22 . The control panel  18  allows the operator to program and run the residual chlorine monitor  10  according to parameters and operations programmed into the controller. Preferably, the electronic controller is a microprocessor located within the case  12  and is easily configured to exchange signals with other devices via a local area network and the like. In another embodiment, the electronic controller is remotely located from the chlorine monitor  10 . 
     Referring to  FIGS. 4-6 , various detailed views of the pump assembly  200  are shown. The pump assembly  200  includes a pump  210 , a pump actuator  230 , first and second reagent tubes  250   a ,  250   b , and check valves  260   a - d . The pump assembly  200  delivers precisely measured and timed dosages of indicator reagent and buffer reagent to the water in the cuvette  30 . 
     The pump  210  is mounted within the case  12  by a bracket  212  and includes a generally cup-shaped pump body  214  having a sidewall  216  extending from an end wall  218  to define an interior pump chamber  220 . The sidewall  216  includes two openings  222  adjacent the end wall  218  for the reagent tubes  250   a ,  250   b  as described below. A housing  232  of the pump actuator  230  is secured to an entrance of the pump chamber  220  (with screw threads and a setscrew  213  for example), as best shown in  FIG. 6 . Referring to  FIG. 6 , the pump  210  also includes a pump hammer  224  within the chamber  220  of the body  214  for reciprocating linear movement between a retracted position moved away from the end wall  218  of the body, as shown in  FIG. 7 , and an extended position moved towards the end wall  218 , as shown in  FIG. 8 . 
     Referring in particular to  FIG. 6 , the pump actuator  230  is a solenoid. The solenoid includes electromagnet coils (not viewable) located in the housing  232  that are electrically activated through pump solenoid wires  233  connected to the electronic controller. A magnetic armature  234  is slidably mounted within a central opening  235  of the housing  232 , and the armature  234  is connected to the hammer  224  of the pump  210  (with set screws  225  for example) so that an electrical charge delivered to the solenoid  230  by the electronic controller causes linear movement of the armature  234 . The upper end of the armature  234  carries a circumferential retaining ring  236 , and a helical pump return spring  238  is disposed between the upper end of the housing  232  and the retaining ring  236 . The return spring  238  normally biases the retaining ring  236  and the attached armature  234  into the retracted position shown in  FIG. 7 . The solenoid  230  is adapted to extend the hammer  224  of the pump  210  when energized and retract the hammer  224  when not energized. 
     With reference to  FIGS. 3-6 , the first reagent tube  250   a  connects the first reagent container  40   a  with the cuvette  30 , and the second reagent tube  250   b  connects the second reagent container  40   b  with the cuvette  30 . Both tubes  250   a ,  250   b  extend from the bottoms of the reagent containers  40   a ,  40   b , through covers  42   a ,  42   b  of the reagent containers, pass through the openings  222  in the pump body  216 , and continue to a nozzle  102 . The nozzle  102  of the colorimeter  100  extends into the cuvette  30 . Air vent tubes  44   a ,  44   b  also extend from the covers  42   a ,  42   b . The openings  222  in the pump sidewall  216  are located so that the tubes  250   a ,  250   b  lay between the hammer  224  and the end wall  218  of the pump  210 . Both tubes  250   a ,  250   b  include an inlet check valve  260   a ,  260   b , respectively, between the reagent containers  40   a ,  40   b  and the pump  210 , and an outlet check valve  260   c ,  260   d , respectively, between the pump  210  and the colorimeter  100 . The check valves  260   a - d  operate to limit the flow of reagent in a single direction from the reagent containers  40   a ,  40   b  to the cuvette  30  during the pumping cycle. The check valves  260   a - d  also prevent air from entering the tubes  250   a ,  250   b  during the pumping cycle. 
     To perform testing, the chlorine monitor  10  is primed, i.e., the reagents are added in equal proportion to a test sample in the cuvette  30 . To prime the monitor  10 , the pump  210  operates so that the reagents are delivered from their respective containers to the cuvette  30 . Typically, the electronic controller is programmed to deliver signals to the pump actuator  230  so that the hammer  224  is repeatably driven between the retracted position shown in  FIG. 7  and the extended position shown in  FIG. 8 . 
     In the extended position shown in  FIG. 8 , the hammer  224  squeezes the segments of the tubes  250   a ,  250   b  in the chamber  220  to a substantially closed position against the end wall  218  of the pump  210  to create pressure in the tubes  250   a ,  250   b . Because the check valves  260   a - d  only allow flow towards the cuvette  30 , the fluid in the tubes  250   a ,  250   b  is urged and moves toward the cuvette  30 . When the hammer  224  returns to the retracted position shown in  FIG. 7 , the outlet check valves  260   c ,  260   d  prevent backflow and a vacuum is created in the tubes to draw the reagents in equal amounts from their respective containers  40   a ,  40   b , through the inlet check valves  260   a ,  260   b , and into the portions of the tubes  250   a ,  250   b  located between the inlet check valves  260   a ,  260   b  and the outlet check valves  260   c ,  260   d.    
     Each tube  250   a ,  250   b  may comprise a single piece or may be formed by conically interconnected separate tube segments  1 - 3 , as shown for example in  FIG. 6  (the tube segments positioned in the reagent containers  40   a ,  40   b  are not shown in  FIG. 6 ). Preferably, the tube segments  250   a - 2 ,  250   b - 2  located within the pump body  214  are resiliently flexible and are composed of silicone or similar material. The diameter may be selected to provide for a desired corresponding pumping pressure. The other tube segments  250   a - 1 ,  250   a - 3 ,  250   b - 1 ,  250   b - 3  may comprise a plastic such as polypropylene or other relatively rigid material. The diameter of the tubes  250   a ,  250   b  is normally relatively small so that excess reagent does not remain within the tube while the pump  210  is not in use. A smaller diameter also helps to facilitate pumping of the reagents through the respective check valves  260   a - d.    
     In the exemplary embodiment shown, the tubes  250   a ,  250   b  have equal diameters and equal lengths such that equal amounts of buffer and indicator reagent are drawn through the pumping operation. The reagent containers  40   a ,  40   b  are thereby depleted together, which facilitates reagent replacement and maintenance of the chlorine monitor  10 . In another embodiment, the separate tubes are combined by a T-shaped fitting to allow a single tube to pass through the pump  210  or a single tube to pass into the cuvette  30 . 
     In another possible embodiment, the reagents are delivered in unequal amounts. One way to accomplish this is to provide duplicate metering pumps for each tube such that the electronic controller can direct compression of one or both tubes at a time. By independently compressing each tube the ratio of delivery can be modified as desired by the user. In other words, the reagents can be delivered in any ratio, which is determined by the ratio of respective hammer strikes. Further, using different size tubing for the tubes can more permanently vary the reagent ratio. 
     Referring now to  FIGS. 9-11 , the colorimeter  100  is shown in detail. Photometric components of the colorimeter  100 , which are shown best in  FIG. 10 , include at least one light source  104  and a light detector or photodiode  106 , for performing colorimetric testing of the sample within the cuvette  30 . The primary light source  104  for measuring the level or concentration of chlorine may comprise, for example, a green light emitting diode (LED)  104  providing a 515 nm light source. Typically, the photodiode  106  is positioned 180° from the primary light source  104 . In operation, the primary light source  104  directs light through the sample water mixed with reagents in the cuvette  30  to the photodiode  106 , which takes measurements representing the level or concentration of chlorine in the water and provides electronic signals representing these measurements. A secondary light source  108 , which is also positioned 180° from the photodiode  106 , is provided for sample level and flow measurement, and may comprise a red LED. The exemplary embodiment also provides a white LED  110  positioned behind the cuvette  30  to illuminate the cuvette  30  for viewing by an operator. 
     The calorimeter  100  includes a body  112  defining a cuvette portal  114  for removably receiving the cuvette  30 , and a passageway  116  extending through the cuvette portal  114 . The nozzle  102  is removably secured in the passageway  116  and is adapted to extend into the cuvette  30  when secured in the passageway  116  and lock the cuvette  30  in the passageway  116 . In the exemplary embodiment shown, the nozzle  102  is secured with screw threads and can be loosened and tightened by hand to release and secure the cuvette  30  during cleaning or replacement of the cuvette  30 . The cuvette  30  is substantially tubular and includes open ends  31   a ,  31   b  that align with the passageway  116  of the body  112 . 
     The discharge ends of the tubes  250   a ,  250   b  enter the nozzle  102  at intersecting angles to provide improved mixing of the reagents. According to one exemplary embodiment a 10° angle is formed between the tubes  250   a ,  250   b  at the top of the nozzle  102 . As shown best in  FIG. 11 , the body  112  of the calorimeter  100  further includes a sample port  118  intersecting the passageway  116 . A tube  33  for the water sample is connected between the water inlet valve  64  (shown best in  FIG. 3 ) and the sample port  118  of the colorimeter  100 . The sample port  118  is offset from a central axis of the passageway  116  of the colorimeter  100  to promote a swirling effect and a mixing of the water and reagents. The sample port  118  extends into the passageway  116  below the cuvette  30 . 
     As shown best in  FIG. 11 , the body  112  of the colorimeter  100  also has an overflow port  120  intersecting the passageway  116  above the cuvette  30 . The nozzle  102  includes side openings  121  for overflow from the cuvette  30  to flow through the overflow port  120  to overflow tubes  74 ,  76  connected to the drain  71  (an air vent tube  78  is connected to the overflow tubes and drain). 
     As shown best in  FIGS. 9 and 11 , the calorimeter  100  includes a spring  122  for ejecting the cuvette  30  out of the cuvette portal  114  upon removal of the nozzle  102  from the cuvette  30 . A resiliently flexible retainer  124  is provided in front of the portal  114  for supporting the ejected cuvette  30  so that the cuvette  30  is not allowed to fall and be damaged. 
     The illustrated embodiments can be understood as providing exemplary features of certain embodiments, and therefore, components and/or aspects of the illustrations can be, without limitation, otherwise combined, interconnected, sequenced, separated, interchanged, positioned, and/or rearranged without materially departing from the disclosed systems or methods. For example, the nozzle and/or discharge tubes may or may not extend into the cuvette. In other embodiments, the discharge tubes may combine the reagent(s) with the fluid remotely from the cuvette and/or the nozzle would facilitate the mixing at another point. For another example, it is envisioned that the reagent(s) can be selected to interact with, and thus monitor, a plurality of compounds independently and collectively such as lead, fluoride and the like. 
     From the foregoing it may be seen that the present disclosure provides for a fluid content monitor  10  with a solenoid-operated pump assembly  200  and a colorimeter  100  including a removable cuvette  30 . While this disclosure has provided a detailed description of exemplary embodiments, numerous modifications and variations of the fluid content monitor  10 , pump assembly  200 , and calorimeter  100 , all within the scope of the disclosure, will readily occur to those skilled in the art. Accordingly, it is understood that this description is illustrative only of the principles of the disclosure and is not limitative thereof.