Sensor for electrometric measurement

Abstract

The invention provides a sensor with a reference electrode and a flowing electrolyte which is particularly useful for measuring the ion concentration of a process solution. The invention includes a sensor having a pressurized reservoir which provides flow of an electrolyte, a non-metallic solution ground and a resistance temperature device bonded to a non-metallic solution ground. The invention provides sensors with greater accuracy and stability by minimizing or eliminating ingress of contaminants from a process solution through the external junction of the sensor.

We claim:  
     
         1 . A sensor of a fluid parameter, the sensor comprising 
 a reference electrode,    an electrolyte in electrolytic contact with the reference electrode,    a pressurized reservoir for providing flow of the electrolyte,    a reference junction, and    an external junction in electrolytic contact with the reference electrode,    wherein the electrolyte flows between the junctions.    
     
     
         2 . The sensor of  claim 1  further comprising a piston for subjecting the electrolyte to a controlled pressure.  
     
     
         3 . The sensor of  claim 2  wherein the piston is a spring actuated piston.  
     
     
         4 . The sensor of  claim 1  further comprising a porous member positioned between the reservoir and the external junction.  
     
     
         5 . The sensor of  claim 4  wherein the porous member is made of glass material.  
     
     
         6 . The sensor of  claim 1  wherein the reference junction comprises a cation exchange membrane.  
     
     
         7 . The sensor of  claim 6  wherein the membrane is a sulphonated polyfluoroethylene membrane.  
     
     
         8 . The sensor of  claim 1  wherein the external junction is made of a ceramic material.  
     
     
         9 . The sensor of  claim 1  further comprising an external pressure source for subjecting said electrolyte to a controlled pressure.  
     
     
         10 . The sensor of  claim 1  further comprising a non-metallic ground disposed at a sensing surface.  
     
     
         11 . The sensor of  claim 10  further comprising a housing wherein the non-metallic ground extends beyond an end of the housing.  
     
     
         12 . The sensor of  claim 11  wherein the non-metallic ground is substantially conical.  
     
     
         13 . A sensor comprising 
 a reference electrode,    an electrolyte in electrolytic contact with the reference electrode,    a pressurized reservoir for providing flow of the electrolyte, and    a non-metallic ground disposed at a sensing surface.    
     
     
         14 . The sensor of  claim 13  wherein the non-metallic ground comprises a conductive polymer.  
     
     
         15 . The sensor of  claim 14  wherein the polymer is polyvinyldifluorine.  
     
     
         16 . The sensor of  claim 13  further comprising a piston in communication with the electrolyte for subjecting the electrolyte to a controlled pressure.  
     
     
         17 . The sensor of  claim 16  wherein the piston is a spring actuated piston.  
     
     
         18 . The sensor of  claim 13  further comprising a porous member positioned between the reservoir and the external junction.  
     
     
         19 . The sensor of  claim 18  wherein the porous member is made of glass material.  
     
     
         20 . The sensor of  claim 13  wherein the reference junction comprises a cation exchange membrane.  
     
     
         21 . The sensor of  claim 20  wherein the membrane is a sulphonated polytetrafluoroethylene membrane.  
     
     
         22 . The sensor of  claim 13  further comprising an external pressure source for subjecting said electrolyte to a controlled pressure.  
     
     
         23 . The sensor of  claim 13  further comprising a housing wherein the non-metallic ground extends beyond an end of the housing.  
     
     
         24 . The sensor of  claim 23  wherein the non-metallic ground is substantially conical.  
     
     
         25 . A sensor comprising 
 a reference electrode,    an electrolyte in electrolytic contact with the reference electrode,    a pressurized reservoir for providing flow of the electrolyte,    a non-metallic ground disposed at a sensing surface, and    a resistance temperature device bonded to the non-metallic ground.    
     
     
         26 . The sensor of  claim 25  wherein the non-metallic ground comprises a conductive polymer.  
     
     
         27 . The sensor of  claim 26  wherein the polymer is polyvinyldifluorine.  
     
     
         28 . The sensor of  claim 25  further comprising a piston in communication with the electrolyte for subjecting the electrolyte to a controlled pressure.  
     
     
         29 . The sensor of  claim 28  wherein the piston is a spring actuated piston.  
     
     
         30 . The sensor of  claim 25  further comprising a porous member positioned between the reservoir and the external junction.  
     
     
         31 . The sensor of  claim 30  wherein the porous member is made of glass material.  
     
     
         32 . The sensor of  claim 25  wherein the reference junction comprises a cation exchange membrane.  
     
     
         33 . The sensor of  claim 32  wherein the membrane is a sulphonated polytetrafluoroethylene membrane.  
     
     
         34 . The sensor of  claim 25  further comprising an external pressure source for subjecting said electrolyte to a controlled pressure.  
     
     
         35 . The sensor of  claim 25  further comprising a housing wherein the non-metallic ground extends beyond an end of the housing.  
     
     
         36 . The sensor of  claim 35  wherein the non-metallic ground is substantially conical.  
     
     
         37 . A pH sensor having a housing and comprising 
 a reference electrode mounted in the housing,    a measuring electrode mounted in the housing and operatively connected to the reference electrode,    a fluid conduit for containing an electrolyte in electrolytic contact with the reference electrode,    a pressurized reservoir for providing flow of the electrolyte and in fluid communication with the fluid conduit,    a reference junction encasing the reference electrode, and    an external junction in electrolytic contact with the reference electrode,    wherein the electrolyte flows between the junctions.    
     
     
         38 . The pH sensor of  claim 37  further comprising a non-metallic ground disposed at a sensing surface.  
     
     
         39 . The pH sensor of  claim 38  wherein the non-metallic ground extends beyond an end of the housing.  
     
     
         40 . The pH sensor of  claim 39  wherein the non-metallic ground is sunbstantially conical.  
     
     
         41 . The pH sensor of  claim 38  wherein the non-metallic ground comprises a conductive polymer.  
     
     
         42 .The pH sensor of  claim 41  wherein the polymer is polyvinyldifluorine.  
     
     
         43 . The pH sensor of  claim 42  further comprising a piston in communication with the electrolyte for subjecting the electrolyte to a controlled pressure.  
     
     
         44 . The pH sensor of  claim 40  wherein the piston is a spring actuated piston.  
     
     
         45 . The pH sensor of  claim 37  further comprising a porous member positioned between the reservoir and the external junction.  
     
     
         46 . The pH sensor of  claim 45  wherein the porous member is made of glass material.  
     
     
         47 . The pH sensor of  claim 37  wherein the reference junction comprises a cation exchange membrane.  
     
     
         48 . The pH sensor of  claim 47  wherein the membrane is a sulphonated polytetrafluoroethylene membrane.  
     
     
         49 . The pH sensor of  claim 37  further comprising an external pressure source for subjecting said electrolyte to a controlled pressure.  
     
     
         50 . The pH sensor of  claim 37  wherein the electrolyte is a solution of AgCl-saturated KCl.  
     
     
         51 . The pH sensor of  claim 37  wherein the reference electrode is made of silver-silver chloride.  
     
     
         52 . A sensor having a housing and comprising 
 a reference electrode mounted in the housing,    an electrolyte in electrolytic contact with the reference electrode,    fluid motive means for creating and controlling flow of the electrolyte, and    a non-metallic ground disposed at a sensing surface.    
     
     
         53 . The sensor of  claim 52  wherein the non-metallic ground extends beyond an end of the housing.  
     
     
         54 . The sensor of  claim 53  wherein the non-metallic ground is substantially conical.  
     
     
         55 . The sensor of  claim 52  further comprising a reference junction positioned between the electrolyte and the reference electrode.  
     
     
         56 . The sensor of  claim 55  wherein the reference junction comprises a cation exchange membrane.  
     
     
         57 . The sensor of  claim 56  wherein the membrane is a sulphonated polytetrafluoroethylene membrane.  
     
     
         58 . The sensor of  claim 52  further comprising an external junction in electrolytic contact with the reference electrode.  
     
     
         59 . The sensor of  claim 58  wherein the external junction is made of ceramic material.  
     
     
         60 . The sensor of  claim 52  wherein the fluid motive means comprises a piston in communication with the electrolyte for subjecting the electrolyte to a controlled pressure.  
     
     
         61 . The sensor of  claim 60  wherein the piston is a spring actuated piston.  
     
     
         62 . The sensor of  claim 52  wherein the fluid motive means comprises a porous member.  
     
     
         63 . The sensor of  claim 62  wherein the porous member is made of glass material.  
     
     
         64 . The sensor of  claim 52  wherein the fluid motive means comprises an external pressure source for subjecting the electrolyte to a controlled pressure.  
     
     
         65 . The sensor of  claim 52  wherein the non-metallic ground comprises a conductive polymer.  
     
     
         66 . The sensor of  claim 65  wherein the polymer is polyvinyldifluorine.  
     
     
         67 . The sensor of  claim 52  further comprising a resistance temperature device bonded to the non-metallic ground.  
     
     
         68 . The sensor of  claim 52  further comprising a measuring electrode operatively connected to the reference electrode.  
     
     
         69 . The sensor of  claim 52  wherein the electrolyte is a solution of AgCl-saturated KCl.  
     
     
         70 . The sensor of  claim 52  wherein the reference electrode is made of silver-silver chloride.  
     
     
         71 . A method of manufacturing a sensor having a resistance temperature device and a 
 non-metallic ground, the method comprising the steps of    melting the non-metallic ground in contact with the device, and    allowing the non-metallic ground to solidify in contact with the device.    
     
     
         72 . The method of manufacturing a sensor according to claim  71  wherein the non-metallic ground is substantially conical.