HIGH TEMPERATURE PRESSURE TRANSMITTER ASSEMBLY

• US 20050284227A1
• Filed: 06/25/2004
• Published: 12/29/2005
• Est. Priority Date: 06/25/2004
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: McGuire, Chad Michael, Orth, Kelly, Sittler, Fred Charles, Broden, David Andrew
• Granted Patent: US 7,036,381 B2
• Time in Patent Office: Days
• US Class Current: 73/708
• CPC Class Codes: G01L 19/0092 Pressure sensor associated with other sensors, e.g. for measuring acceleration or temperature G01L9/025, G01L9/045, G01L9/065, G01L9/085, G01L9/105, G01L9/125, G01L19/02, G01L19/04 take precedence; measuring two or more variable G01D21/02; temperature sensors with pressure compensation G01K1/26
• CPC Class Codes: G01L 19/0645 using isolation membranes, specially adapted for protection
• CPC Class Codes: G01L 19/0681 Protection against excessive heat

Abstract

A pressure transmitter assembly for measuring a pressure of a process fluid includes an isolation diaphragm assembly. A pressure sensor is spaced apart from the isolation diaphragm assembly to provide thermal isolation. A conduit extends from the isolation diaphragm assembly to the pressure sensor and is configured to carry isolation fill fluid.

Claims

1. A pressure transmitter assembly for measuring a pressure of a process fluid, comprising:

an isolation diaphragm assembly including an isolation diaphragm configured to couple to a process fluid along a process interface side and defining an isolated cavity opposite the process interface side;

a pressure sensor coupled to the isolation diaphragm assembly and physically spaced apart from the diaphragm assembly to provide thermal isolation from process fluid proximate the isolation diaphragm assembly; and

a conduit extending from the isolated cavity defined by the isolation diaphragm to the pressure sensor, the conduit configured to carry isolation fill fluid to thereby transfer a pressure applied to the isolation diaphragm to the pressure sensor.

2. The apparatus of claim 1 including a transmitter support which couples a transmitter module to the isolation diaphragm assembly.

3. The apparatus of claim 2 wherein the transmitter support has a relatively low thermal conductivity.

4. The apparatus of claim 2 wherein the transmitter support comprises a support formed with a relatively thin wall.

5. The apparatus of claim 2 wherein the transmitter support is tubular.

6. The apparatus of claim 2 wherein the transmitter support comprises a plastic.

7. The apparatus of claim 2 wherein the transmitter module couples to the transmitter support with a potting compound.

8. The apparatus of claim 2 wherein the spacing between the isolation diaphragm assembly and the pressure transmitter module includes an air gap.

9. The apparatus of claim 1 wherein the isolation diaphragm assembly includes a vent port.

10. The apparatus of claim 9 including a vent pressure tube extending between the pressure transmitter module and the vent port.

11. The apparatus of claim 1 including a sensor module which includes a pressure port.

12. The apparatus of claim 11 including a pressure transmitter module having an electrical connection coupled to circuitry in the sensor module.

13. The apparatus of claim 12 wherein the pressure transmitter module includes output electronics electrically coupled to circuitry in the sensor module by the electrical connection.

14. The apparatus of claim 12 wherein the electrical connection comprises a flex circuit.

15. The apparatus of claim 1 including a temperature sensor for use in compensating variations in pressure measurements due to temperature variations.

16. The apparatus of claim 1 including a plurality of temperature sensors for use in compensation variations in pressure measurements due to temperature variation.

17. The apparatus of claim 1 including a thermally conductive material which thermally couples the pressure sensor to a thermal sensor carried on an electronic circuit board in the pressure transmitter.

18. The apparatus of claim 1 wherein a space between the pressure sensor and the isolation diaphragm is more than about 1.3 inches.

19. The apparatus of claim 1 wherein the thermal conductivity from the isolation diaphragm to the pressure sensor is less than about 1 W/M °

K.

20. A method of manufacturing a pressure transmitter for coupling to a high temperature process fluid comprising:

providing an isolation diaphragm assembly including an isolation diaphragm configured to couple to a process fluid along a process interface side and defining an isolated cavity opposite the process interface side;

providing a pressure sensor;

affixing the pressure sensor to the isolation diaphragm assembly at a physically spaced apart position from the diaphragm assembly to provide thermal isolation from process fluid proximate the isolation diaphragm assembly; and

coupling the isolated cavity defined by the isolation diaphragm to the pressure sensor with a conduit, the conduit configured to carry isolation fill fluid to thereby transfer a pressure applied to the isolation diaphragm to the pressure sensor.

21. The method of claim 20 wherein the affixing includes providing a transmitter support which couples to the isolation diaphragm assembly.

22. The method of claim 21 wherein the transmitter support has a relatively low thermal conductivity.

23. The method of claim 21 including filling the transmitter support with a potting compound.

24. The method of claim 20 wherein the isolation diaphragm assembly includes a vent port and the method includes coupling a pressure transmitter module to the vent port.

25. The method of claim 20 including providing a temperature sensor for use in compensation variations in pressure measurements due to temperature variations.

26. The method of claim 25 including providing a plurality of temperature sensors for use in providing temperature compensation.