Flowserve Logix MD+ ValveSight - Manual (Page 256)

ValveSight™ Diagnostics DTM Manual for Logix MD+ Positioner with HART®
FCD- LGENSF0014-00
© Flowserve Corporation
256
Characterization Configuration
The Characterization Selection field displays which curve is active in the positioner. The
custom curve can be generated on this page, but must be activated by changing the curve
to Custom on the
Stroke Characterization page.
The Retrieval Progress bar shows the status of retrieving the curve from the positioner.
Characterization Curve
The
Characterization Curve box allows you to quickly load a rangeability curve or manually
modify the curve.
Inherent Rangeability (R) is defined as the change in which the deviation from a
desired inherent flow characteristic will not exceed some stated controllable limits. It is
generally used to describe the ratio of the minimum controllable flow to the maximum
controllable flow in terms of Valve Cv. In practice, the inherent rangeability is the ratio
between maximum and minimum controllable Cv, where Cv is the valve flow
coefficient representing valve capacity.
In the formula,
n is the Output Signal
R is the value in the input field (default is 30)
i is the Input Signal
Selecting the graph button will calculate the new curve based on the R value.
Selecting the button will reset the curve to the last retrieved or applied curve.
The Input Signal column represents the X axis of the graph and is not adjustable. The
Output Signal column represents the Y axis of the graph. The Output Signal may be edited
by typing, clicking the up/down buttons or dragging points on the the graph.