Automated mechanical integrity verification

• US 20080157987A1
• Filed: 12/28/2006
• Published: 07/03/2008
• Est. Priority Date: 12/28/2006
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Hedtke, Robert C.
• Granted Patent: US 7,692,539 B2
• Time in Patent Office: Days
• US Class Current: 340/603
• CPC Class Codes: G01L 27/007 Malfunction diagnosis, i.e. diagnosing a sensor defect

Abstract

A process transmitter for sensing a process variable of a process fluid includes a process sensor, transmitter circuitry, a transmitter housing and a transmitter mounting component. The process sensor senses the process variable of the process fluid and the transmitter circuitry processes a signal from the process sensor. The transmitter housing receives the process sensor and transmitter circuitry, and the transmitter mounting component isolates the sensor or the transmitter circuitry from the process fluid or external environment. The mechanical integrity sensor validates assembly of the transmitter housing and transmitter mounting component.

Claims

1. A process transmitter for measuring a process variable, the process transmitter comprising:

a process sensor for sensing the process variable of a process fluid;

transmitter circuitry for processing a signal from the process sensor;

a transmitter housing for receiving the process sensor and transmitter circuitry;

at least one transmitter mounting component for isolating the sensor or the transmitter circuitry from the process fluid or external environment; and

a mechanical integrity sensor for validating assembly of the transmitter housing and transmitter mounting component.

2. The process transmitter of claim 1 wherein:

the transmitter housing includes at least one access opening for the process sensor or the transmitter circuitry;

the transmitter access opening is mechanically sealed with a transmitter mounting component; and

the mechanical integrity sensor comprises a proximity sensor for sensing proximity of the transmitter mounting component to the housing.

3. The process transmitter of claim 2 wherein the transmitter circuitry verifies that the transmitter mounting component is fully seated with the access opening such that the transmitter mounting component prevents contaminants from entering the housing.

4. The process transmitter of claim 2 wherein the transmitter circuitry verifies that the transmitter mounting component is properly threaded with the housing such that the component provides an adequate flame quenching channel.

5. The process transmitter of claim 2 wherein the transmitter circuitry includes predetermined values for comparison to a signal generated by the mechanical integrity sensor.

6. The process transmitter of claim 1 wherein:

the transmitter mounting component comprises a process flange for joining the transmitter housing with the process fluid; and

the mechanical integrity sensor comprises a material verification sensor for sensing material properties of the process flange.

7. The process transmitter of claim 6 wherein the transmitter circuitry validates the sensed material property of the process flange with material property data stored in the transmitter circuitry.

8. The process transmitter of claim 6 wherein the material verification sensor comprises an inductive permeability sensor.

9. The process transmitter of claim 6 and further comprising a second material verification sensor for sensing material properties of a process diaphragm positioned within the process transmitter.

10. The process transmitter of claim 1 wherein the transmitter circuitry includes electronics that annunciate to a user output of the mechanical integrity sensor.

11. The process transmitter of claim 1 wherein the transmitter circuitry operates the mechanical integrity sensor as a continuous background operation.

12. The process transmitter of claim 1 wherein the transmitter circuitry includes a user control such that a user is able to manually initiate operation of the mechanical integrity sensor.

13. The process transmitter of claim 1 wherein the

the transmitter mounting component comprises a sensor module for joining the transmitter housing with a process fluid flange;

and

the mechanical integrity sensor comprises a proximity sensor for sensing orientation of the transmitter housing on the sensor module.

14. A process transmitter for measuring a process variable, the process transmitter comprising:

a process sensor module for sensing the process variable of a process fluid;

a transmitter housing for receiving the process sensor;

at least one housing cover for sealing the sensor within the housing; and

a mechanical integrity sensor for sensing assembly of the housing cover or sensor module with the transmitter housing.

15. The process transmitter of claim 14 wherein the mechanical integrity sensor comprises a proximity sensor.

16. The process transmitter of claim 15 wherein the proximity sensor is selected from the group consisting of an inductive proximity sensor, a capacitive proximity sensor, a magnetometer, an ultrasonic proximity sensor, an optical proximity sensor or a mechanical limit switch.

17. The process transmitter of claim 14 and further comprising electronic circuitry that annunciates when a housing cover or sensor module is improperly positioned or missing.

18. The process transmitter of claim 14 further comprising transmitter circuitry which includes predetermined proximity values for comparison to a signal generated by the mechanical integrity sensor.

19. The process transmitter of claim 14 wherein the mechanical integrity sensor is comprised of a capacitive proximity sensor.

20. The process transmitter of claim 19 wherein the capacitive proximity sensor comprises:

a first capacitor comprising a first terminal screw and a second terminal screw;

a second capacitor comprising the first terminal screw and a housing cover; and

a third capacitor comprising the second terminal screw and the housing cover;

wherein the capacitance of the circuit formed by the first, second and third capacitors changes as the housing cover is assembled with the transmitter housing.

21. The process transmitter of claim 14 wherein the mechanical integrity sensor comprises an inductive proximity sensor.

22. The process transmitter of claim 21 wherein the inductive proximity sensor comprises:

an inductance coil for generating an electrostatic field positioned within the sensor housing adjacent a housing cover;

a core material positioned within the inductance coil;

an oscillator for generating an eddy current in the core; and

a signal level detector for sensing a change in an amplitude of oscillation of the eddy current when a housing cover is positioned near the core.

23. A process transmitter for measuring a process variable, the process transmitter comprising:

a process sensor for sensing the process variable of a process fluid;

a transmitter housing for receiving the process sensor;

a process flange for joining the transmitter housing with a process fluid source; and

a mechanical integrity sensor for verifying material properties of the process flange.

24. The process transmitter of claim 23 wherein the mechanical integrity sensor comprises an inductive permeability sensor.

25. The process transmitter of claim 24 wherein the inductive permeability sensor comprises:

an inductance coil for generating an electrostatic field positioned within the sensor housing adjacent a housing cover;

a core material positioned within the inductance coil;

an oscillator for generating an eddy current in the core; and

a signal level detector for sensing a change in an amplitude of oscillation of the eddy current when the process flange is positioned near the core.

26. The process transmitter of claim 23 and further comprising a second material verification sensor for sensing material properties of a process diaphragm positioned within the process transmitter.

27. The process transmitter of claim 23 and further comprising transmitter circuitry including predetermined material property values for comparison to a signal generated by the mechanical integrity sensor.

28. The process transmitter of claim 27 and further comprising electronic circuitry that annunciates when the signal generated by the mechanical integrity sensor differs from a predetermined material property value.