Amperometric Sensor System

• US 20120216605A1
• Filed: 02/13/2012
• Published: 08/30/2012
• Est. Priority Date: 02/15/2011
• Status: Active Grant

• Current Assignee: Halogen Systems, Inc.
• Original Assignee: Michael A. Silveri
• Inventors: Silveri, Michael A.
• Granted Patent: US 8,887,556 B2
• Time in Patent Office: Days
• US Class Current: 73/61.41
• CPC Class Codes: F04D 1/04 Helico-centrifugal pumps
• CPC Class Codes: G01N 27/06 of a liquid involving electrolysis G01N27/26
• CPC Class Codes: G01N 27/08 which is flowing continuously
• CPC Class Codes: G01N 27/4168 Oxidation-reduction potential, e.g. for chlorination of water water analysis G01N33/18
• CPC Class Codes: G01N 33/18 Water
• CPC Class Codes: G01N 33/1893 using flow cells
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A sensor system that measures at least one parameter of water includes an electronics subsystem and includes a sensor housing electrically and mechanically coupled to the electronics subsystem. The sensor housing encloses a chamber that receives water via at least one inlet and that releases water via at least one outlet. At least one sensor has at least one electrode exposed to water in the chamber. A flow generator causes water to flow through the chamber. A plurality of objects within the chamber move in response to the water flow and abrasively clean the at least one electrode. Preferably, the sensor system includes a chlorine sensor having at least two electrodes. The electronics subsystem applies a first differential voltage between the two electrodes during a measurement interval and then applies a second differential voltage between the two electrodes during an interval following the measurement interval.

Claims

1. A sensor system for measuring at least one parameter of water, comprising:

an electronics subsystem;

a sensor housing electrically and mechanically coupled to the electronics subsystem, the sensor housing comprising;

a chamber that receives water via at least one inlet and that releases water via at least one outlet;

at least one sensor having at least one electrode exposed to water in the chamber; and

a flow generator that causes water to flow through the chamber.

2. The sensor system as defined in claim 1, wherein the sensor housing is configured to be inserted into a pipe carrying the water for which the parameter is to be measured.

3. The sensor system as defined in claim 1, wherein:

the flow generator is a pump that comprises a motor and an impeller;

the sensor housing comprises a wet side exposed to water and a dry side isolated from water;

the motor is mounted on the dry side of the sensor housing;

the impeller is mounted on the wet side of the sensor housing; and

the impeller is magnetically coupled to the motor such that rotation of the motor on the dry side of the housing rotates the impeller on the wet side of the housing.

4. The sensor system as defined in claim 3, wherein the motor comprises a brushless DC motor.

5. The sensor system as defined in claim 1, wherein the sensor system is an amperometric sensor system.

6. The sensor system as defined in claim 1, wherein the sensor system further comprises a plurality of movable objects constrained within the chamber and movable by water flowing in the chamber to impinge upon and clean a surface of the at least one electrode.

7. The sensor system as defined in claim 6, wherein the movable objects comprise glass spheres.

8. The sensor system as defined in claim 6, wherein the movable objects comprise polytetrafluoroethylene (PTFE) spheres.

9. The sensor as defined in claim 6, wherein the movable objects have dimensions sufficiently larger than the at least one inlet and the at least one outlet such that the movable objects are confined to the chamber.

10. The sensor system as defined in claim 1, wherein the at least one sensor comprises at least three electrodes, and wherein the at least three electrodes are cleaned simultaneously.

11. The sensor system as defined in claim 10, wherein the at least three electrodes are cleaned simultaneously by a plurality of movable objects moving within the chamber as water flows through the chamber.

12. The sensor system as defined in claim 1, wherein the at least one electrode comprises the electrodes in a chlorine sensor and the electrodes in a pH sensor, and wherein the electrodes in the chlorine sensor and the electrodes in the pH sensor are cleaned simultaneously.

13. The sensor system as defined in claim 12, wherein the at least three electrodes are cleaned simultaneously by a plurality of movable objects within the chamber as water flows through the chamber.

14. The sensor system as defined in claim 1, wherein the at least one outlet of the chamber is positioned so that any air in the chamber exits through the at least one outlet.

25. The sensor system as defined in claim 1, wherein:

the sensor system is a multi-use sensor system for sensing pH in water;

the electronics subsystem is enclosed within an electronics base unit that houses electronics circuitry common to a plurality of sensor applications; and

the sensor housing comprises a removable sensor cartridge that houses at least one replaceable pH sensor, wherein the replaceable pH sensor in the removable sensor cartridge is configured to be one of;

a differential pH sensor;

a combination pH sensor and reference electrode; and

a reference only sensor.

26. The multi-use sensor system as defined in claim 25, wherein:

the replaceable pH sensor has a first sensing end having a flared body portion and has a second connecting end having a sensor connector fixed thereon, the replaceable pH sensor having a fixed length between the flared body portion and the sensor connector; and

the removable sensor cartridge includes a flared cavity configured to receive the flared body portion of the replaceable pH sensor and has a mating connector configured to mate with the sensor connector and positioned to electrically and mechanically engage the sensor connector when the flared body portion of the replaceable pH sensor is positioned within the flared cavity.

15-24. -24. (canceled)

27-29. -29. (canceled)

30. A method of cleaning an amperometric sensor having a plurality of electrodes positioned on the face of a sensor body, each of the plurality of electrodes having a surface exposed to water having at least one parameter to be measured by the plurality of electrodes, the method comprising:

confining a plurality of movable objects in a cavity that comprises a volume of water exposed to the surfaces of the plurality of electrodes;

flowing water into, through and out of the cavity to cause the water to flow across the surfaces of the plurality of electrodes; and

circulating the plurality of movable objects within the cavity to cause the plurality of movable objects to impinge on the surfaces of the plurality of electrodes as the water flows through the cavity, the plurality of movable objects abrading the surfaces of the plurality of electrodes to thereby clean the electrodes.

31. The method as defined in claim 30, wherein the movable objects are spherical.

32. The method as defined in claim 30, wherein the movable objects comprise glass.

33. The method as defined in claim 30, wherein the movable objects comprise polytetrafluoroethylene (PTFE).

34. The method as defined in claim 30, in which a control system electrically coupled to the sensor probe applies differential voltages between at least a first electrode of the plurality of electrodes and a second electrode of the plurality of electrodes, the control system:

generating a first differential measuring voltage in a range between −

0.2 volt and +0.5 volt between the first electrode and the second electrode; and

generating a second differential voltage between 0 volt and −

5.0 volts between the first electrode and the second electrode, the second differential voltage applied for a duration of at least 0.1 second following the first differential measuring potential.

35. The method as defined in claim 30, wherein the water is seawater and the oxidant levels measured are between 1 and 500 ppm.

36-38. -38. (canceled)

39. A method of operating an amperometric sensor having a plurality of electrodes positioned on the face of a sensor body, each of the plurality of electrodes having a surface exposed to water having at least one parameter to be measured by the plurality of electrodes, the method comprising:

positioning the surfaces of the plurality of electrodes in a cavity that comprises a volume of water;

operating a flow generator to flow the water having the at least one parameter to be measured into, through and out of the cavity to cause the water to flow across the surfaces of the plurality of electrodes at a substantially constant velocity; and

measuring the at least one parameter of the water while the water is flowing across the surfaces of the plurality of electrodes.

40. The method as defined in claim 39, wherein the flow generator comprises an impeller and comprises a motor to impart rotation to the impeller, the method further comprising:

positioning the impeller in the cavity to expose the impeller to the water in the cavity;

positioning the motor outside the cavity in a location isolated from the water, the motor mechanically coupled to a first rotatable coupling device outside the cavity;

applying energy to the motor to rotate the first rotatable coupling device; and

magnetically coupling the first rotatable coupling device to the impeller within the cavity to cause the impeller to rotate within the cavity.

41. The method as defined in claim 40, wherein:

the motor has a motor torque; and

the first rotatable coupling device is coupled to the impeller with at least a minimum coupling force, the minimum coupling force selected to be greater than the motor torque so that the motor will not rotate the first coupling device if the impeller cannot rotate.

42. A method for reducing build-up of contamination on a sensor, comprising

positioning a surface of a sensor in an enclosure having at least one inlet to allow water to enter the enclosure and having at least two outlets to allow water to exit the enclosure, the enclosure containing a plurality of movable particles, the movable particles having dimensions selected to prevent the movable particles from passing out of the enclosure via the outlets;

and

flowing water within the enclosure from the inlet to the outlets to cause the water to flow over the surface of the sensor, the flow of the water causing at least some of the movable particles to impinge on the surface of the sensor to dislodge contamination from the surface of the sensor, the outlets oriented with respect to a direction of flow of the water to inhibit the movable particles from blocking the at least two outlets.

43. An apparatus, comprising

an enclosure that houses a surface of a sensor adapted to measure a characteristic of water, the enclosure having at least one inlet to allow water to enter the enclosure and having at least two outlets to allow water to exit the enclosure, the enclosure containing a plurality of movable particles, the movable particles having dimensions selected to prevent the movable particles from passing out of the enclosure via the outlets;

and

a flow generator that produces a flow of water within the enclosure from the inlet to the outlets to cause the water to flow over the surface of the sensor, the flow of the water causing at least some of the movable particles to impinge on the surface of the sensor to inhibit build-up of contaminates on the surface, the outlets oriented with respect to the flow of the water to inhibit the movable particles from blocking the outlets.

44. The apparatus as defined in claim 43, wherein the enclosure comprises an inner cavity configured to constrain the movable particles in a volume proximate to the surface of the sensor, the inner cavity having a shape selected to cause the movable particles to move in a circulating pattern within the inner cavity.

45. The apparatus as defined in claim 44, wherein the shape of the inner cavity is generally ovoidal.