Remote seal process pressure measuring system

Patent metadata

Field	Value
Publication number	US-9274018-B2
Application number	US-201213630998-A
Country	US
Kind code	B2
Filing date	Sep 28, 2012
Priority date	Sep 28, 2012
Publication date	Mar 1, 2016
Grant date	Mar 1, 2016

Abstract

A process pressure measuring system includes a transmitter having a first sealed system in which a first outlet couples to a pressure sensor, a first isolator diaphragm assembly, a first capillary passage, and a first isolation fluid. The first isolation fluid couples a first pressure from the first isolator diaphragm to the first outlet and the pressure sensor. A second sealed system includes a second pressure outlet that is coupled to the first isolator diaphragm assembly, a second isolator diaphragm assembly, a second capillary passage and a second isolation fluid. The second isolation fluid is adapted for use in a first temperature range and couples a pressure from the second isolator diaphragm assembly to the second pressure outlet. A third sealed system includes a third pressure outlet that is coupled to the second isolator diaphragm assembly, a third isolator diaphragm assembly, a third capillary passage and a third isolation fluid. The third isolator fluid is adapted for use in a second temperature range and couples a process pressure to the third pressure outlet.

First claim

What is claimed is:

1. A process pressure measuring system, comprising:
a first sealed system that includes a first pressure outlet, a pressure sensor, a first isolator diaphragm assembly and a first capillary passage filled with a first isolation fluid that couples a process pressure from the first isolator diaphragm assembly through the first capillary passage and the first pressure outlet to the pressure sensor;
a second sealed system removably mounted to the first sealed system and that includes a second open pressure outlet, a second isolator diaphragm assembly and a second capillary passage filled with a second isolation fluid for use in a first temperature range, the second isolation fluid coupling the process pressure from the second isolator diaphragm assembly through the second capillary passage and the second open pressure outlet to the first isolator diaphragm assembly and including a first fill tube coupled to the second capillary passage, the first fill tube used to fill the second capillary passage with the second isolation fluid;
a third sealed system removably mounted to the second sealed system and that includes a third pressure outlet, a third isolator diaphragm assembly, couplable to a source of the process pressure in a second temperature range, different than the first temperature range, and a third capillary passage filled with a second isolation fluid, different than the first isolation fluid, that couples the process pressure from the third isolator diaphragm assembly through the third capillary passage and the third pressure outlet to the second isolator diaphragm assembly and including a second fill tube coupled to the third capillary passage, the second fill tube used to fill the third capillary passage with the third isolation fluid; and
the process pressure coupling through the third, second and first sealed systems to the sensor, and the use of isolation fluids with different temperature ranges reducing inaccuracies in a sensed pressure at the pressure sensor.

2. The process pressure measuring system of claim 1 wherein the first sealed system comprises a transmitter.

3. The process pressure measuring system of claim 2 , wherein the use of second and third isolation fluids with different temperature ranges reduces inaccuracies in a sensed pressure output of the transmitter.

4. The process pressure measuring system of claim 2 , further comprising:
a flange that engages the third isolator diaphragm assembly, and that is rotatable to align with process vessel mounting holes for field-removable coupling to the process fluid.

5. The process pressure measuring system of claim 2 wherein the second isolation fluid comprises a fill fluid that is free flowing below a first temperature.

6. The process pressure measuring system of claim 5 wherein the first temperature is 0 degrees Centigrade.

7. The process pressure measuring system of claim 2 wherein the third isolation fluid comprises a fill fluid that does not vaporize below a second temperature.

8. The process pressure measuring system of claim 7 wherein the second temperature is 350 degrees Centigrade.

9. The process pressure measuring system of claim 2 wherein the second isolator assembly introduces a second pressure drop, and the second pressure drop is corrected by a compensation algorithm in the pressure transmitter.

10. The process pressure measuring system of claim 2 wherein the third isolator assembly introduces a third pressure drop, and the third pressure drop is corrected by a compensation algorithm in the pressure transmitter.

11. The process pressure measuring system of claim 1 , further comprising:
a flange that engages the third isolator diaphragm assembly, and that is rotatable to align with process vessel mounting holes for field-removable coupling to the process fluid.

12. The process pressure measuring system of claim 1 wherein the second isolation fluid comprises a fill fluid that is free flowing below a first temperature.

13. The process pressure measuring system of claim 1 wherein the second isolation fluid comprises a fill fluid that does not vaporize at a temperature below a second temperature.

14. The process pressure measuring system of claim 1 wherein the second isolator assembly introduces a dynamic pressure loss that is controllable by the selection of the second isolation fluid.

15. The process pressure measuring system of claim 1 wherein the third isolator assembly includes a support tube that couples between the third isolator assembly and the third pressure outlet.

16. A circuit, comprising:
a performance calculation circuit that calculates multiple error limits related to a remote seal system comprising the first, second and third sealed systems of claim 1 as a function of system data related to the remote seal system, and that provides multiple error limit data;
an input circuit that receives the system data and that provides the system data to the performance computation circuit; and
a display driver circuit that receives the error limit data and that provides a display driver output that includes the error limit data presented in a visual display format.

17. The circuit of claim 16 wherein the performance calculation circuit includes a gate array.

18. The circuit of claim 16 wherein the performance calculation circuit includes a custom integrated circuit that performs error limit calculation.

19. The circuit of claim 16 wherein the performance calculation circuit includes a microprocessor system that performs the error limit calculation under control of a computer operating system.

20. A method for coupling to a first sealed system and a pressure sensor in a pressure transmitter to a dual temperature remote seal system, the method comprising:
removably mounting a second sealed system to the first sealed system, the second sealed system having a second pressure outlet that is open and fluidly couplable to the first sealed system, a second isolator diaphragm assembly, a second capillary passage, and a second isolation fluid, for use in a first temperature range, the second isolation fluid coupling pressure from the second isolator diaphragm assembly through the second capillary passage to the second pressure outlet;
filling the second capillary passage with the second isolation fluid through a first fill tube which couples to the second capillary passage;
sealing the first fill tube;
removably mounting a third sealed system to the second sealed system, the third sealed system having a third pressure outlet that is open and fluidly couplable to the second isolator diaphragm assembly, a third isolator diaphragm assembly, a third capillary passage, and a third isolation fluid, for use in a second temperature range, the third isolation fluid coupling pressure from the third isolator diaphragm assembly through the third capillary passage to the third pressure outlet;
filling the third capillary passage with the third isolation fluid through a second fill tube which couples to the third capillary passage;
sealing the second fill tube; and
coupling a process pressure through the third, second and first sealed systems to the pressure sensor, the use of second and third isolation fluids with different temperature ranges reducing inaccuracies in a sensed pressure at the pressure sensor.

21. The method of claim 20 , further comprising:
providing a flange that engages the third isolator diaphragm assembly, and that is rotatable to align with process vessel mounting holes for fi

Assignees

• Rosemount Inc

Inventors

• Miller Brent Wayne
• Fadell Paul Ryan

Classifications

• G01L13/026

  involving double diaphragm · CPC title

• G01L19/0046 Primary

  using isolation membranes (G01L13/026 and G01L19/0645 take precedence) · CPC title

• G01L27/007

  Malfunction diagnosis, i.e. diagnosing a sensor defect · CPC title

• G01L19/0618 Primary

  Overload protection · CPC title

• G01L19/0681

  Protection against excessive heat · CPC title