•
Quick Opening:
The quick opening characterization is the inverse to the Equal Percentage (50)
characterization curve.
•
Custom Characterization:
A custom characterization defines the relationship between the input
signal and the output position of the valve. Selecting this option will display an additional window
where you can configure a characterization curve with 10 adjustable segments to fit your needs. The
curve can have up to 9 adjustable points and points in between are linearly interpolated
To configure a customer characteristic curve, you enter the values in the edit boxes at the bottom of the
screen and pressing the Tab key. The graph is updated when the value is entered. Alternatively, you
can use a mouse to do the job:
•
Change the shape of the curve by clicking a point, holding the left mouse button down, and dragging
the cursor to a new position before releasing the mouse button.
•
Add a point by clicking the left mouse button at the desired location.
•
Delete a point by clicking the point with the right mouse button.
After configuring the curve, click the OK button to accept the value and exit the Custom Characterization
window, or click the Cancel button to exit without changing the values. To prevent a user to enter unrea-
sonable points, ValVue will check the curve based on established rules and pop up warning message
when the curve does not meet the rules. In addition, these points are saved in SVI with a resolution of
0.4%, the entered value and its saved value may differ slightly by 0.2%. It is important to reenter the
Custom Characterization window and make sure the curve is as desired.
44
Figure 36. Custom Characterization Window
Note:
Linear positioner characteristic is generally used when the valve trim is characterized.
