Valve assembly calibration

Patent metadata

Field	Value
Publication number	US-9739682-B2
Application number	US-201514703494-A
Country	US
Kind code	B2
Filing date	May 4, 2015
Priority date	May 4, 2015
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

A method for correcting calibration of a closure member on a valve assembly. The method can include comparing a calculated value to an expected value, each relating to a position of a closure member of the valve assembly relative to a seat of the valve assembly, the calculated value being calculated using a calibration variable and an input value corresponding to a measured position of the closure member. The method can also include identifying a deviation between the calculated value and the expected value. The method can further include changing the calibration variable from a first value to a second value in response to the deviation, the second value equating the calculated value at the input value with the expected value for the position.

First claim

What is claimed is:

1. A valve assembly, comprising:
a valve comprising a closure member that is configured to move relative to a seat; and
a valve positioner configured to,
compare a calculated value to an expected value that define a position of the closure member of the valve assembly relative to the seat of the valve assembly, the calculated value being calculated using a calibration variable and an input value corresponding to a measured position of the closure member, wherein the calibration variable comprises a first calibration variable and a second calibration variable, and wherein the second value corresponds to one or more of the first calibration variable and the second calibration variable;
identify a deviation between the calculated value and the expected value;
change the calibration variable from a first value to a second value in response to the deviation, the second value equating the calculated value at the input value with the expected value for the position of the closure member relative to the seat in the valve assembly,
calculate the second value for the first calibration variable and the second calibration variable in accordance with,

C

v
⁢

⁢
1
⁢
new

=

C

v
⁢

⁢
1
⁢
old

(

1
-

Pos
c

)

,
and

C

v
⁢

⁢
2
⁢
new

=

C

v
⁢

⁢
2
⁢
old

-

Pos
c

(

1
-

Pos
c

)

,
and

 generate a pneumatic signal to move the closure member to the calculated value for the position of the closure member relative to the seat that corresponds with the second value,
wherein C v1new is the second value for the first calibration variable Cv 1 , C v1old is a first value for the first calibration variable C v1 , C v2new is the second value for the second calibration variable Cv2, C v2old is a first value for the second calibration variable C v2 , and Pos c is the calculated value.

2. The valve assembly of claim 1 , wherein the valve positioner is further configured to compare the calculated value to the expected value to arrive at the deviation.

3. The valve assembly of claim 1 , wherein the valve positioner is further configured to,
calculate the deviation in accordance with,
d =Pos c −Pos e ,

wherein d is the deviation, Pos c is the calculated value, and Pos e is the expected value.

4. The valve assembly of claim 1 , wherein the valve positioner is further configured to,
determine a drift condition in the input value, wherein the drift condition corresponds to a value for the deviation that satisfies a threshold criteria, and wherein the second value corrects the calculated position that results from the drift condition.

5. The valve assembly of claim 1 , wherein the valve positioner is further configured to,
calculate the second value for the second calibration variable in accordance with,
C vnew =C vold −Pos c ,

wherein C vnew is the second value for the calibration variable, C vold is a first value for the calibration variable that is different from the second value C vnew , and Pos c is the calculated value.

6. The valve assembly of claim 1 , further comprising a sensor coupled with the valve positioner and configured to generate an input signal that relates to the input value,
wherein the valve positioner is further configured to,
calculate the calculated value according to,
Pos c =S i *C v1 +C v2 ,

wherein S i is the input value from the sensor, C v1 is the first calibration variable, and C v2 is the second calibration variable, and
wherein the second calibration variable C v2 assumes the second value.

7. The valve assembly of claim 1 , wherein the valve positioner is further configured to,
require an input that acknowledges that the first value is to be different from the second value.

8. The valve assembly of claim 7 , wherein the valve positioner is further configured to,
generate an alert in response to the deviation, wherein the alert is configured to solicit the input.

9. A valve positioner, comprising:
a processor;
a storage memory coupled with the processor; and
executable instructions stored on the storage memory and configured to be executed by the processor, the executable instructions comprising instructions for,
comparing a calculated value to an expected value that define a position of the closure member of the valve assembly relative to the seat of the valve assembly, the calculated value being calculated using a calibration variable and an input value corresponding to a measured position of the closure member, wherein the calibration variable comprises a first calibration variable and a second calibration variable, and wherein the second value corresponds to one or more of the first calibration variable and the second calibration variable;
identifying a deviation between the calculated value and the expected value; and
changing the calibration variable from a first value to a second value in response to the deviation, the second value equating the calculated value at the input value with the expected value for the position by calculating the second value for the first calibration variable and the second calibration variable in accordance with,

C

v
⁢

⁢

Assignees

• Dresser Inc

Inventors

• Schoonover Larry Gene
• Shriver Justin Scott

Classifications

• F16K37/0083 Primary

  by measuring valve parameters · CPC title

• G01L27/005 Primary

  Apparatus for calibrating pressure sensors · CPC title