Process fluid pressure sensing assembly for pressure transmitters subjected to high working pressure

• US 9,459,170 B2
• Filed: 09/26/2013
• Issued: 10/04/2016
• Est. Priority Date: 09/26/2013
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Haywood, Nicholas John
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): DUNLAP, JONATHAN M
• Application Number:
  US14/038,223
• Publication Number:
  US 20150082893A1
• Time in Patent Office: 1,104 Days
• Field of Search: 737/06, 737/14, 737/16, 737/24
• US Class Current: 1/1
• CPC Class Codes: G01L 15/00 Devices or apparatus for measuring two or more fluid pressure values simultaneously
• CPC Class Codes: G01L 19/0084 to the outside of the housing other details about the housing see G01L19/14
• CPC Class Codes: G01L 19/0645 using isolation membranes, specially adapted for protection
• CPC Class Codes: G01L 19/143 Two part housings
• CPC Class Codes: G01L 27/007 Malfunction diagnosis, i.e. diagnosing a sensor defect
• CPC Class Codes: G01L 7/082 construction or mounting of diaphragms of semiconductive diaphragms G01L9/0042
• CPC Class Codes: G01L 9/0041 Transmitting or indicating the displacement of flexible diaphragms

Abstract

A pressure measurement assembly is provided. The assembly includes a pressure sensor mount having an aperture therethrough. A pressure sensor passes through and is mounted to the aperture. The pressure sensor has an electrical characteristic that varies with applied pressure. An isolator plug is configured to be exposed to a process fluid. The isolator plug has an isolation diaphragm disposed to contact the process fluid. A passageway is fluidically coupled to the isolation diaphragm to convey process fluid pressure from the isolation diaphragm to the pressure sensor through an incompressible fluid. The pressure sensor mount is coupled to the isolator plug and has a non-circular shape when viewed along an axis of the aperture.

Claims

1. A transmitter for measuring a process variable of a process field comprising:

a housing;

a pipe flange coupled to the housing configured to mount the transmitter to an opening in a pipe;

a probe extending from the flange and into pipe through the opening in the pipe;

a pressure sensor mount in the probe having an aperture therethrough;

a pressure sensor passing through and mounted to the aperture, the pressure sensor having an electrical characteristic that varies with applied pressure;

an isolator plug in the probe configured to be exposed to a process fluid and having a cavity formed therein which carries the pressure sensor and the pressure sensor mount therein, the isolator plug having an isolation diaphragm disposed to contact the process fluid and a passageway fluidically coupled to the isolation diaphragm to convey process fluid pressure from the isolation diaphragm to the pressure sensor through an incompressible fluid; and

wherein the pressure sensor mount is coupled to the isolator plug and has a non-circular shape when viewed along an axis of the aperture.

2. The pressure measurement assembly of claim 1, and further comprising a fill tube coupled to the isolator plug and configured to introduce the incompressible fluid into the passageway.

3. The pressure measurement assembly of claim 2, wherein the fill tube is mounted to the isolator plug and extends from the isolator plug in a direction substantially parallel with the axis of the aperture.

4. The pressure measurement assembly of claim 1, wherein the pressure sensor mount is brazed to the isolator plug.

5. The pressure measurement assembly of claim 1, and further comprising a screen disposed over the isolation diaphragm.

6. The pressure measurement assembly of claim 5, wherein the screen is welded to the isolator plug.

7. The pressure measurement assembly of claim 1, wherein the pressure sensor is formed of a single-crystal material.

8. The pressure measurement assembly of claim 7, wherein the single-crystal material is sapphire.

9. The pressure measurement assembly of claim 1, and further comprising at least one incompressible volume insert positioned proximate a portion of the pressure sensor and disposed in the incompressible fluid.

10. The pressure measurement assembly of claim 1, wherein the assembly is embodied within a pressure probe and is part of a pressure transmitter.

11. The pressure measurement assembly of claim 1, wherein the pressure sensor further includes at least one temperature sensitive element disposed to provide an indication of process fluid temperature.

12. The pressure measurement system of claim 1, wherein the isolator plug is formed of a corrosion-resistant alloy.

13. The pressure measurement system of claim 12, wherein the corrosion-resistant alloy is C 276.

14. The pressure measurement system of claim 12, wherein the corrosion-resistant alloy is Inconel 625.

15. The pressure measurement system of claim 1, wherein the non-circular shape is substantially oval.

16. A transmitter for measuring a process variable of a process field comprising:

a housing;

a pipe flange coupled to the housing configured to mount the transmitter to an opening in a pipe;

a probe extending from the flange and into pipe through the opening in the pipe;

a first pressure sensor mount in the probe having a first aperture therethrough;

a first pressure sensor passing through and mounted to the first aperture, the first pressure sensor having an electrical characteristic that varies with applied pressure;

a second pressure sensor mount in the probe having a second aperture therethrough;

a second pressure sensor passing through and mounted to the second aperture, the second pressure sensor having an electrical characteristic that varies with applied pressure;

an isolator plug in the probe configured to be exposed to a process fluid and having first and second cavities formed therein which carry the first and second pressure sensors and the first and second pressure sensor mounts, respectively therein, the isolator plug having a first isolation diaphragm disposed to contact process fluid and including a first passageway fluidically coupled to the first isolation diaphragm to convey process fluid pressure from the first isolation diaphragm to the first pressure sensor through an incompressible fluid, the isolator plug also having a second isolation diaphragm disposed to contact process fluid and including a second passageway fluidically coupled to the second isolation diaphragm to convey process fluid pressure from the second isolation diaphragm to the second pressure sensor through an incompressible fluid; and

wherein the first and second pressure sensor mounts are coupled to the isolator plug and have a non-circular shape when viewed along an axis of the first aperture.

17. The pressure sensor assembly of claim 16, wherein the first and second isolation diaphragms are circular.

18. The pressure sensor assembly of claim 17, wherein the first and second isolation diaphragms are spaced apart with respect to an axis of the isolator plug.

19. The pressure sensor assembly of claim 18, wherein first and second isolation diaphragms are aligned with one another.

20. The pressure sensor assembly of claim 16, and further comprising a screen coupled to the isolator plug, and wherein each isolation diaphragm is spaced from the screen.

21. The pressure sensor assembly of claim 20, wherein the screen includes a number of apertures disposed proximate an interface with the isolator plug.

22. The pressure measurement assembly of claim 16, and further comprising:

a first fill tube coupled to the isolator plug and configured to introduce incompressible fluid into the first passageway; and

a second fill tube coupled to the isolator plug and configured to introduce incompressible fluid into the second passageway.

23. The pressure measurement assembly of claim 22, wherein the first and second fill tubes extend from the isolator plug in a direction substantially parallel with the axis of the aperture.

24. The pressure measurement assembly of claim 22, wherein the assembly has a diameter of about 0.98″

or less.

25. The pressure measurement assembly of claim 16, wherein the first and second pressure sensors are each formed of a single-crystal material.

26. The pressure measurement assembly of claim 16, wherein the non-circular shape is substantially oval.