Among the aforementioned five types of the diagnostic tests, the standard valve diagnostic test strokes
the valve over its full range and should not be run with the valve in service and the process running.
The extended valve actuator signature, positioner signature and step profile tests allow the user to enter
the starting point, end point, time duration or number of sampling of the test. Clicking the Stop
Procedure button in Diagnostic window that appears during the test can halt any of the valve diagnostic
tests.
SVI must be switched to manual mode first in order to access the diagnostic mode. Clicking the
Diagnostic button in the Manual Mode window will retrieve current continuous diagnostic data from the
SVI and display them in the Diagnostics window (figure 43 shown on next page).
To exit the Diagnostics window, click the Manual button to exit to manual mode.
Continuous Diagnostics
ValVue retrieves current diagnostic data from the SVI and display them in Continuous Diagnostic Data
box in the Diagnostics window. These data include:
•
Total Travel:
Valve travel accumulated in the unit of number of full strokes.
•
Number of Cycles:
The number of times the valve travel changes direction.
•
Time Open:
The time the valve has spent fully open
•
Time Closed:
The time the valve has been fully closed
•
Time Near Closed:
The time the valve has spent throttling near the seat.
These continuous diagnostic data are also accessible via a HART command #139 Read Continuous
Diagnostic Data in the normal operating mode or manual mode.
To reset continuous data, click the Reset Continuous Data button under the Diagnostic Data box. A
warning message box will appear. If you click OK, the continuous diagnostic data (Total Travel, Number
of Cycle, Time Open, Time Closed, and Time Near Closed) will be reset to 0. When reset, the previous
values are lost. We recommend recording the continuous diagnostic data before clearing.
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Note:
Limiting a signature or step test to a small range may allow you to conduct the test with
an acceptable upset to the process under some circumstances.