Pressure transmitter with improved isolator system

• US 6,662,662 B1
• Filed: 05/04/2000
• Issued: 12/16/2003
• Est. Priority Date: 05/04/2000
• Status: Expired due to Term

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Romo, Mark G., Johnson, Thomas E., Louwagie, Bennett L., Nord, Christina A., Schansberg, Todd W., Harasyn, Donald E., Rud, Stanley E. Jr., Horky, David A., Ballot, William J., Szafranski, Kevin P., Patrick, Renae M., Sherin, Matthew G., Guttsen, Kenneth G., Eidenschink, Ryan R., Hedtke, Robert C., Behm, Steven M., Brekken, Jeffrey C.
• Primary Examiner(s): Hershfeld, Andrew H.
• Assistant Examiner(s): FERGUSON SAMRETH, MARISSA LIANA
• Application Number:
  US09/564,506
• Time in Patent Office: 1,321 Days
• Field of Search: 73/70, 733/98, 73/40, 73/80, 737/18, 737/24, 737/53, 738/61, 375/295, 361/283, 361/283--28, 338/2, 338/42, 600/538
• US Class Current: 73/715
• CPC Class Codes: G01L 19/0618 Overload protection
• CPC Class Codes: G01L 19/0645 using isolation membranes, specially adapted for protection
• CPC Class Codes: G01L 19/0663 Flame protection; Flame barriers

Abstract

A pressure transmitter with a fluid isolator that includes a sensor tube and a fill tube that have “D” shaped ends that connect together in a port internal to the transmitter. The shaped ends can be brazed into the port for sealing. Fitting both the sensor tube and the fill tube in the same port provides a low cost isolator with reduced isolator liquid volume. The fluid isolator has an isolator diaphragm with a central diaphragm region overlying a central backing plate that includes a annular groove. The annular groove avoids slow response of the isolator after an overpressure condition.

Claims

1. A pressure transmitter with an improved isolator system, comprising:

a transmitter body having an external isolator rim around a shaped concavity that is liquidly coupled to a port internal to the transmitter through a passageway through the body, the concavity having a central backing plate region;

an isolator diaphragm having a diaphragm rim sealed to the isolator rim and having a central diaphragm region overlying and spaced apart from the central backing plate region;

isolator liquid between the isolator diaphragm and the shaped concavity and in the passageway;

a pressure sensor receiving pressure from the port through a sensor tube with a first shaped end disposed in the port, the sensor generating a pressure output;

a fill tube internal to the transmitter and adapted to seal off the isolator, the fill tube having a second shaped end disposed in the port; and

the central backing plate region including an annular groove that intersects with passageway.

2. The pressure transmitter of claim 1 wherein the first and second shaped ends are brazed in the port.

3. The pressure transmitter of claim 2 wherein the first and second shaped ends have shapes that are approximately a “

D”

shape.

4. The pressure transmitter of claim 3 wherein transmitter body includes a raised boss surrounding the port.

5. The pressure transmitter of claim 4 wherein the pressure transmitter is a differential pressure transmitter.

6. A pressure transmitter with an improved isolator system, comprising:

a transmitter body having an external isolator rim around a shaped concavity that is liquidly coupled to a port internal to the transmitter through a passageway through the body, the concavity having a central backing plate region;

an isolator diaphragm having a diaphragm rim sealed to the isolator rim and having a central diaphragm region overlying and spaced apart from the central backing plate region;

isolator liquid between the isolator diaphragm and the shaped concavity and in the passageway;

a pressure sensor receiving pressure from the port through a sensor tube with a first shaped end disposed in the port, the sensor generating a pressure output;

a fill tube internal to the transmitter and adapted to seal off the isolator, the fill tube having a second shaped end disposed in the port; and

the fill tube and the sensor tube being shaped to fit together in the port and brazed in the port.

7. The pressure transmitter of claim 6 wherein the central backing plate region includes a annular groove that intersects with the passageway and is filled with isolator liquid.

8. The pressure transmitter of claim 7 wherein the annular groove is shaped as an undulation having a depth sufficient to avoid valve-off.

9. The pressure transmitter of claim 8 wherein the groove remains filled with isolator liquid under overpressure conditions.

10. The pressure transmitter of claim 9 wherein the passageway intersects with the groove at the bottom of the groove.

11. A pressure transmitter with an improved isolator system, comprising:

a transmitter body having an external isolator rim around a shaped concavity that is liquidly coupled to a port internal to the transmitter through a passageway through the body, the concavity having a central backing plate region;

an isolator diaphragm having a diaphragm rim sealed to the isolator rim and having a central diaphragm region overlying and spaced apart from the central backing plate region;

isolator liquid between the isolator diaphragm and the shaped concavity and in the passageway;

a pressure sensor receiving pressure from the port through a sensor tube with a first shaped end disposed in the port, the sensor generating a pressure output; and

a fill tube internal to the transmitter and adapted to seal off the isolator, the fill tube having a second shaped end disposed in the port.

12. A pressure transmitter with an improved isolator system, comprising:

a transmitter body having an external isolator rim around a shaped concavity that is liquidly coupled to a port internal to the transmitter through a passageway through the body, the concavity having a central backing plate region;

an isolator diaphragm having a diaphragm rim sealed to the isolator rim and having a central diaphragm region overlying and spaced apart from the central backing plate region;

isolator liquid between the isolator diaphragm and the shaped concavity and in the passageway;

a pressure sensor receiving pressure from the port through a sensor tube with a first shaped end disposed in the port, the sensor generating a pressure output;

a fill tube internal to the transmitter and adapted to seal off the isolator, the fill tube having a second shaped end disposed in the port; and

means for providing, in the central backing plate region, an annular groove that intersects with the passageway.