Abstract:
A sensor for detection and measurement of a particular substance present in a liquid is disclosed. The sensor includes a non-circular or non-symmetrically fixed electrode for detection and measurement of a particular substance present in a liquid in which said sensor is submersed. The sensor with non-circular or non-symmetrically fixed electrode and method of using the same reduces or eliminates electrode deformation upon residue removal therefrom thereby prolonging operating life.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/700,459; filed on Sep. 13, 2012, entitled “CLEANING AND GRINDING OF SULFITE SENSOR HEAD” which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a method and an apparatus for cleaning and grinding sulfite sensor heads, and more specifically, to a method and an apparatus for cleaning and grinding sulfite sensor electrodes that reduces or eliminates electrode deformation and resultant changes in sensor signaling. 
     BACKGROUND OF THE INVENTION 
     Sensors used to measure the presence of a particular substance in a liquid typically use metallic electrodes. Over a period of sensor use, these electrodes must be periodically cleaned. Today, cleaning of sensor electrodes is accomplished using a rotating ceramic cleaning and grinding “stone”. The electrode to be cleaned is a relatively thin metallic ring set in a plastic base. To clean the electrode, a planar surface of the rotating ceramic stone is brought into contact with an exposed electrode ring surface that extends beyond the surface of the plastic base. As such, the rotation of the ceramic stone removes residue from the exposed surface of the electrode ring. Over time, both the electrode ring wears down and the ceramic stone wears down. When the ceramic stone wears down, a groove is formed in the formerly planar surface thereof. Upon using such a worn ceramic stone to clean an electrode, the groove formed in the surface of the ceramic stone modifies the grinding and cleaning capabilities of the ceramic stone. As a result, effective grinding and cleaning of the electrode is compromised. In cleaning and grinding an electrode with a worn ceramic stone, the electrode becomes “smeared out” or deformed over a portion of the surface of the adjacent plastic base in which the electrode is set. This smearing or deformation of the electrode changes the surface area and functioning of the electrode. As such, electrode deformation compromises the electrode&#39;s signaling capabilities. Because compromises to electrode signaling are unacceptable as causing detection inaccuracies, electrodes and ceramic stones for cleaning and grinding must be replaced often. 
     Due to capital costs and operational costs associated with frequent electrode and ceramic stone replacement, a need exists for improvement. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to reduce groove-forming ceramic stone wear and electrode deformation over that of the prior art. The electrode sensor and ceramic stone apparatus and method of the present invention achieve this objective as well as others, as described below. 
     The present sensor useful for measuring the presence of a particular substance in a liquid includes an electrode manufactured from a metal, such as for example platinum, silver, gold or another metal of like characteristics. The metal electrode is fixed in a planar surface of a plastic base so as to be raised above the planar surface and amply exposed. In manufacturing the sensor, a plastic base is preferred due to cost considerations. However, other materials could likewise be used as a base for fixing the electrode, such as ceramic or glass. The base in which the metal electrode is set is preferably of like dimension and design as that of the prior art so as to be readily interchangeable therewith on existing equipment without requiring associated equipment modification(s). 
     The electrode fixed in the base is of an oval, elliptical, square or other non-circular shape, or non-symmetrically fixed circular shape. Sensors having electrodes of oval, elliptical, square or other non-circular shape, or non-symmetrically fixed circular shape, allows for improved electrode wear and a prolonged sensor operational life over that of the prior art sensor. 
     As noted briefly above, the present sensor is useful to detect and quantify an amount of a substance in a liquid, such as for example an amount of ions in a liquid or slurry or an amount of sulfite in water. However, with use, residue builds on the surface of the sensor electrode. With residue build-up, the electrode requires cleaning for residue removal therefrom to ensure proper and accurate sensor operation and function. Hence, periodically to remove residue from the electrode, the electrode is contacted with a relatively flat or planar contact surface of a rotating ceramic stone. The rotating ceramic stone is commonly referred to as a grinding and cleaning stone. Contact with the ceramic stone abrades the residue so as to again expose a clean electrode surface. Because the present electrodes are non-circular in shape, or if circular, non-symmetrically fixed, the planar surface of the ceramic stone contacting the electrodes is worn more evenly so as to reduce or eliminate groove formation therein. By reducing or eliminating groove formation in the relatively planar contact surface of the ceramic stone, deformation or “smearing” of the metal electrode cleaned thereby is likewise reduced or eliminated. As such, the useful operating life of both the sensor and the ceramic stone are significantly extended. Extending the useful operating life of both the sensor and the ceramic stone reduces both capital and operational costs associated therewith. 
     The present sensor for detection and measurement of a particular substance present in a liquid, comprises a base with an interior edge, an exterior edge and a top surface extending between the interior edge and the exterior edge, with a non-circular or non-symmetrical electrode fixed on said top surface for detection and measurement of a particular substance present in a liquid in which said sensor is submersed. The sensor base is manufactured from a plastic, glass or ceramic material. The sensor electrode is manufactured from a metal, such as from silver, gold, platinum or a combination thereof. The electrode is of a non-circular shape, such as oval, elliptical, square or an oscillating form. Alternatively, an electrode of circular shape may be used if non-symmetrically fixed to the sensor base. An example of a particular substance detected and measured by the sensor is sulfite present in water or ions present in a liquid or slurry. 
     A method of using the present sensor for detection and measurement of a particular substance present in a liquid, comprises submerging the sensor comprising a base with an interior edge, an exterior edge, a top surface extending between the interior edge and the exterior edge, and a non-circular or non-symmetrically fixed electrode on said top surface, in a liquid for detection and measurement of a particular substance present in the liquid and periodically cleaning residue from the electrode using a rotating ceramic stone. According to this method the sensor base is manufactured from a plastic, glass or ceramic material. The electrode is manufactured from a metal, such as silver, gold, platinum or a combination thereof. The non-circular electrode is oval, elliptical, square or an oscillating form. Alternatively, an electrode of circular shape may be used if non-symmetrically fixed to the sensor base. An example of a particular substance detected and measured by the sensor is sulfite present in water or ions present in a liquid or slurry. 
     A method of cleaning and grinding the present sensor electrode, comprises attaching a ceramic stone offset from center to a rotating arm so as to cause the ceramic stone to follow a non-circular path around the rotating arm, and contacting a sensor electrode with a contact surface of the ceramic stone for cleaning and grinding of residue from the sensor electrode with reduced wear or prevention of grooved wear of the contact surface. 
     Further objects and features of the present invention will be apparent from the following description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is now described in more detail with reference to the appended drawings. 
         FIG. 1  is a top perspective view of an electrode sensor of the prior art. 
         FIG. 2  is a top perspective view of the bottom of a worn rotating ceramic stone of the prior art. 
         FIG. 3  is a top perspective view of the electrode sensor of  FIG. 1  after having been contacted with the worn ceramic stone of  FIG. 2 . 
         FIG. 4  is a top perspective view of a sensor according to the present disclosure. 
         FIG. 5  is a top perspective view of another embodiment of a sensor according to the present disclosure. 
         FIG. 6  is a top perspective view of another embodiment of a sensor according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , is a prior art sensor  10 . Sensor  10  comprises a plastic base  12  defined by an exterior side surface  22  and an interior side surface  20 . Interior side surface  20  defines a center aperture  24  through base  12 . Extending between exterior side surface  22  and interior side surface  20  of base  12  is top surface  26  and opposed bottom surface (not shown). An interior edge  16  defines the intersection of top surface  26  and interior side surface  20 . Likewise, an exterior edge  14  defines the intersection of top surface  26  and exterior side surface  22 . Fixed in top surface  26  is a circular electrode  18  arranged symmetrically an equidistance between interior edge  16  and exterior edge  14 . In use, electrode  18  is submerged in a liquid to detect and quantify a particular substance present in the liquid. Over time with such use, residue builds on electrode  18  requiring electrode  18  to be cleaned for continued proper operation and use. 
     Referring to  FIG. 2 , is a prior art ceramic stone  40  useful for cleaning and grinding electrodes  18  such as that of sensor  10 . Ceramic stone  40  has a base  44  with an aperture  46  therethrough for removable attachment to a rotating arm (not shown) of associated equipment (not shown). Opposite aperture  46  on base  44  is an elevated contact member  42 . Elevated contact member  42  includes a planar contact surface  54 . 
     In using ceramic stone  40  to clean and grind electrode  18  of sensor  10 , contact surface  54  is arranged for direct contact with electrode  18 . As ceramic stone  40  rotates, leading side edge  52  of ceramic stone  40  moves over a portion of top surface  26  of sensor  10 . As such, interior edge  50  of contact member  42  rotates over interior edge  16  of top surface  26 . Likewise, exterior edge  48  of contact member  42  rotates over exterior edge  14  of top surface  26 . Over time, as contact member  42  rotates over top surface  26  with contact surface  54  in direct contact with electrode  18 , a groove  56  is worn into contact surface  54 . Once contact surface  54  is worn to have a groove  56  therein, proper cleaning and grinding of electrode  18  is compromised. 
     As best illustrated in  FIG. 3 , is a sensor  10  deformed from cleaning and grinding with a ceramic stone  40  worn to have a groove  56  in contact surface  54 . In rotation of ceramic stone  40  with groove  56  in direct contact with electrode  18  for cleaning and grinding of electrode  18  for removal of residue, electrode  18  is deformed by groove  56 . Electrode  18  in its deformed state is “smeared out” over portions of base  12 . As such, the surface area of electrode  18  is altered and proper operation and function of electrode  18  is compromised. 
     To address the problem associated with wear to ceramic stone  40  and resultant deformation of electrode  18  as described above and illustrated in  FIGS. 1 through 3 , the present apparatus embodiment is disclosed herein and illustrated in  FIG. 4 . The present apparatus as illustrated in  FIG. 4  has features in common with those illustrated in  FIG. 1 . As such, features illustrated in  FIG. 4  common to those of  FIG. 1  are signified using the same numbers but with the number “4” preceding them. 
     Illustrated in  FIG. 4  is a sensor  410 . Sensor  410  comprises a plastic base  412  defined by an exterior side surface  422  and an interior side surface  420 . Interior side surface  420  defines a center aperture  424  through base  412 . Extending between exterior side surface  422  and interior side surface  420  of base  412  is top surface  426  and opposed bottom surface (not shown). An interior edge  416  defines the intersection of top surface  426  and interior side surface  420 . Likewise, an exterior edge  414  defines the intersection of top surface  426  and exterior side surface  422 . Fixed in top surface  426  is a non-circular electrode  418  arranged with a varying distance between interior edge  416  and exterior edge  414 . In use, electrode  418  is submerged in a liquid to detect and quantify a particular substance present in the liquid. Over time with such use, residue builds on electrode  418  requiring electrode  418  to be cleaned for continued proper operation and use. 
     In using a ceramic stone  40  in a method to clean and grind electrode  418  of sensor  410 , contact surface  54  is arranged for direct contact with electrode  418 . As ceramic stone  40  rotates, leading side edge  52  of ceramic stone  40  moves over a portion of top surface  426  of sensor  410 . As such, interior edge  50  of contact member  42  rotates over interior edge  416  of top surface  426 . Likewise, exterior edge  48  of contact member  42  rotates over exterior edge  414  of top surface  426 . As contact member  42  rotates over top surface  426  with contact surface  54  in direct contact with electrode  418 , no groove  56  is worn into contact surface  54  since non-circular electrode  418  is arranged with a varying distance between interior edge  416  and exterior edge  414 . This variation in distance between interior edge  416  and exterior edge  414  reduces or prevents electrode  418  from wearing a groove  56  in contact surface  54  of ceramic stone  40 . Hence, proper cleaning and grinding of electrode  418  is preserved, and the useful life of ceramic stone  40  is preserved, to achieve a prolonged operating life. 
     Another embodiment to address the problems associated with wear to ceramic stone  40  and resultant deformation of electrode  18  as described above with reference to  FIGS. 1 through 3 , is disclosed herein and illustrated in  FIG. 5 . The present apparatus as illustrated in  FIG. 5  has features in common with those illustrated in  FIG. 1 . As such, features illustrated in  FIG. 5  common to those of  FIG. 1  are signified using the same numbers but with the number “5” preceding them. 
     Illustrated in  FIG. 5  is a sensor  510 . Sensor  510  comprises a plastic base  512  defined by an exterior side surface  522  and an interior side surface  520 . Interior side surface  520  defines a center aperture  524  through base  512 . Extending between exterior side surface  522  and interior side surface  520  of base  512  is top surface  526  and opposed bottom surface (not shown). An interior edge  516  defines the intersection of top surface  526  and interior side surface  520 . Likewise, an exterior edge  514  defines the intersection of top surface  526  and exterior side surface  522 . Fixed in top surface  526  is a non-circular electrode  518  arranged with a varying distance between interior edge  516  and exterior edge  514 . In use, electrode  518  is submerged in a liquid to detect and quantify a particular substance present in the liquid. Over time with such use, residue builds on electrode  518  requiring electrode  518  to be cleaned for continued proper operation and use. 
     In using a ceramic stone  40  in a method to clean and grind electrode  518  of sensor  510 , contact surface  54  is arranged for direct contact with electrode  518 . As ceramic stone  40  rotates, leading side edge  52  of ceramic stone  40  moves over a portion of top surface  526  of sensor  510 . As such, interior edge  50  of contact member  42  rotates over interior edge  516  of top surface  526 . Likewise, exterior edge  48  of contact member  42  rotates over exterior edge  514  of top surface  526 . As contact member  42  rotates over top surface  526  with contact surface  54  in direct contact with electrode  518 , no groove  56  is worn into contact surface  54  since non-circular electrode  518  is arranged with a varying distance between interior edge  516  and exterior edge  514 . This variation in distance between interior edge  516  and exterior edge  514  reduces or prevents electrode  518  from wearing a groove  56  in contact surface  54  of ceramic stone  40 . Hence, proper cleaning and grinding of electrode  518  is preserved, and the useful life of ceramic stone  40  is preserved, to achieve a prolonged operating life. 
     Still another embodiment to address the problems associated with wear to ceramic stone  40  and resultant deformation of electrode  18  as described above with reference to  FIGS. 1 through 3 , is disclosed herein and illustrated in  FIG. 6 . The present apparatus as illustrated in  FIG. 6  has features in common with those illustrated in  FIG. 1 . As such, features illustrated in  FIG. 6  common to those of  FIG. 1  are signified using the same numbers but with the number “6” preceding them. 
     Illustrated in  FIG. 6  is a sensor  610 . Sensor  610  comprises a plastic base  612  defined by an exterior side surface  622  and an interior side surface  620 . Interior side surface  620  defines a center aperture  624  through base  612 . Extending between exterior side surface  622  and interior side surface  620  of base  612  is top surface  626  and opposed bottom surface (not shown). An interior edge  616  defines the intersection of top surface  626  and interior side surface  620 . Likewise, an exterior edge  614  defines the intersection of top surface  626  and exterior side surface  622 . Fixed in top surface  626  is a non-circular electrode  618  arranged with a varying distance between interior edge  616  and exterior edge  614 . In use, electrode  618  is submerged in a liquid to detect and quantify a particular substance present in the liquid. Over time with such use, residue builds on electrode  618  requiring electrode  618  to be cleaned for continued proper operation and use. 
     In using a ceramic stone  40  in a method to clean and grind electrode  618  of sensor  610 , contact surface  54  is arranged for direct contact with electrode  618 . As ceramic stone  40  rotates, leading side edge  52  of ceramic stone  40  moves over a portion of top surface  626  of sensor  610 . As such, interior edge  50  of contact member  42  rotates over interior edge  616  of top surface  626 . Likewise, exterior edge  48  of contact member  42  rotates over exterior edge  614  of top surface  626 . As contact member  42  rotates over top surface  626  with contact surface  54  in direct contact with electrode  618 , no groove  56  is worn into contact surface  54  since non-circular electrode  618  is arranged with a varying distance between interior edge  616  and exterior edge  614 . This variation in distance between interior edge  616  and exterior edge  614  reduces or prevents electrode  618  from wearing a groove  56  in contact surface  54  of ceramic stone  40 . Hence, proper cleaning and grinding of electrode  618  is preserved, and the useful life of ceramic stone  40  is preserved, to achieve a prolonged operating life. 
     Non-circular electrode  418 ,  518 ,  618  may be of any shape that varies the arranged distance of electrode  418 ,  518 ,  618  between interior edge  416 ,  516 ,  616  and exterior edge  414 ,  514 ,  614 . Such shapes include oval, elliptical, square and oscillating forms. Less complex shapes and forms are preferred for ease in manufacture and thereby reduced cost. Alternatively, an electrode of circular shape may be used if non-symmetrically fixed to the sensor base. As such, the non-symmetrically fixed circular electrode would not be fixed to have a consistent equidistance between interior edge  16  and exterior edge  14 . 
     Another approach to address the problems associated with wear to ceramic stone  40  and resultant deformation of electrode  18  as described above with reference to  FIGS. 1 through 3 , is to modify the attachment of the ceramic stone  40  through aperture  46  to a rotating arm (not shown) of associated equipment (not shown). As such, ceramic stone  40  is attached to the rotating arm (not shown) offset from center for offset revolution thereabout. With ceramic stone  40  no longer rotating along a circular path, but rather rotating along an oval path due to the offset revolution, groove  56  is not formed. For further explanation, by rotating ceramic stone  40  along an oval path, contact between electrode  18  and contact surface  54  is not static, but rather oscillates over a broader surface area of contact surface  54 . Contact over a broader surface area of contact surface  54 , reduces or prevents wearing of groove  56  in contact surface  54 . 
     While the preferred embodiments has been shown and described in relation to apparatus and methods of cleaning and grinding sensor electrodes, various modifications may be made thereto by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the invention has been described by way of illustration and is to be limited only in accordance with the claims appended hereto.