FLOWMETER VERIFICATION ON A MAGNETIC FLOWMETER

• US 20080078252A1
• Filed: 09/28/2007
• Published: 04/03/2008
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: Micro Motion Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Foss, Scot R., Schulz, Robert K., Graber, William F.
• Granted Patent: US 7,750,642 B2
• Time in Patent Office: Days
• US Class Current: 73/861.16
• CPC Class Codes: G01F 1/60 Circuits therefor
• CPC Class Codes: G01F 25/10 of flowmeters

Abstract

A magnetic flowmeter is provided including a magnetic flowtube arranged to receive a flow of process fluid. The magnetic flowtube includes a drive coil and at least one sense electrode. Measurement circuitry is coupled to the flowtube and is configured to provide a drive signal to the drive coil and measure flow of process fluid through the flow tube based upon an output from the sense electrode. A memory contains a stored value related to a nominal parameter of the flowtube. Verification circuitry is arranged to measure a parameter of the magnetic flowtube and responsively provide a verification output related to operation of the magnetic flowmeter based upon a comparison of the measured parameter and the stored value.

Claims

1. A magnetic flowmeter, comprising:

a magnetic flowtube arranged to receive a flow of process fluid, the magnetic flowtube including a drive coil and at least one sense electrode;

measurement circuitry coupled to the flowtube configured to provide a drive signal to the drive coil and measure flow of process fluid through the flow tube based upon an output from the at least one sense electrode;

a memory configured to contain a stored value related to a nominal parameter of the flowtube; and

verification circuitry arranged to measure a parameter of the magnetic flowtube and responsively provide a verification output related to operation of the magnetic flowmeter based upon a comparison of the measured parameter and the stored value.

2. The apparatus of claim 1 wherein the measurement circuitry is configured to measure flow during operation of the verification circuitry.

3. The apparatus of claim 1 wherein the verification circuitry is configured to measure resistance of a coil of the flowtube.

4. The apparatus of claim 1 wherein the verification circuitry is configured to measure inductance of a coil of the flowtube.

5. The apparatus of claim 1 wherein the verification circuitry is configured to measure resistance of electrodes of the flowtube to process ground.

6. The apparatus of claim 1 wherein the verification circuitry is further configured to measure an output placed on a two-wire process control loop.

7. The apparatus of claim 1 wherein the verification circuitry is configured to measure a current level of current of the drive signal applied to the drive coil by the measurement circuitry.

8. The apparatus of claim 1 wherein the nominal parameter value is stored in the memory during manufacture or during initial installation of the flowmeter.

9. The apparatus of claim 1 wherein the nominal parameter value is stored in the memory by the verification circuitry.

10. The apparatus of claim 1 wherein the memory is configured to store a plurality of nominal parameters and the verification circuitry provides the verification output based upon a comparison of a plurality of measured parameters and the plurality of stored nominal parameters.

11. The apparatus of claim 1 wherein the nominal parameter value is selected from the group of values consisting of pulse output, digital inputs and digital outputs.

12. The apparatus of claim 1 wherein the nominal parameter value is stored in the memory during operation of the magnetic flowmeter at a field location.

13. A method for verifying operation of a magnetic flowmeter, comprising:

electrically coupling to a magnetic flowtube arranged to receive a flow of process fluid, the flowtube coupled to a flow of process fluid, the magnetic flowtube including a drive coil and at least one sense electrode;

measuring a parameter of the magnetic flowtube;

retrieving a stored value related to a nominal parameter of the flowtube; and

providing a verification output based upon a comparison of the measured parameter of the magnetic flowtube and a stored value related to a nominal value of the flowtube.

14. The method of claim 13 wherein measuring a parameter comprises measuring resistance of a coil of the flowtube.

15. The method of claim 13 wherein measuring a parameter comprises measuring inductance of a coil of the flowtube.

16. The method of claim 13 wherein measuring a parameter comprises measuring resistance of electrodes of the flowtube.

17. The method of claim 13 wherein measuring a parameter comprises further measuring an output placed on a two-wire process control loop.

18. The method of claim 13 wherein the verification circuitry is configured to measure a current level of current of the drive signal applied to the drive coil by the measurement circuitry.

19. The method of claim 13 wherein the nominal parameter value is stored in the memory during manufacture or during initial installation of the flowmeter.

20. The method of claim 13 wherein the nominal parameter value is stored in the memory by the verification circuitry.

21. The method of claim 13 including storing a plurality of nominal parameters and the verification output is based upon a comparison of a plurality of measured parameters and the plurality of stored nominal parameters.