Flowserve Logix MD+ ValveSight - Manual (Page 62)

ValveSight™ Diagnostics DTM Manual for Logix MD+ Positioner with HART®
FCD- LGENSF0014-00
© Flowserve Corporation
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Legend
The legend shows the purpose of the icons.
Action Buttons
The Apply button will save changes to the connected device.
The Retrieve button will retrieve the latest information from the device.
Indicators
Friction High
•
Definition: The valve and actuator friction has passed the user set
limit.
•
Implications: High friction can cause loop oscillations, poor position
control, jerky motion, or valve sticking. It can be caused by build-up
from the process on the stem, trim or seat , by a failing bearing or
guides in the valve and actuator, galling of the trim or stem, excessively
tightened packing, linkages, or other valve or actuator mechanical
issues.
•
Possible Solutions: Determine if the friction is significantly interfering
with the valve control. If not, consider increasing the friction warning
limit. Consider the following to reduce friction: Stroke the valve to clear
off build-up. Clear any external mechanical obstruction, loosen the
packing, clean the stem, repair or replace the actuator. Highly localized
friction or very jerky travel can indicate internal galling. Repair or
replace internal valve components.
Friction Low
•
Definition: The friction has passed below the user set limit.
•
Implications: Low friction is an indication of improperly loaded packing
and, in severe cases, can be an indication of the process fluid leaking at
the valve stem.
•
Possible Solutions: Check for packing leak. Tighten or replace the
valve packing.
Valve Cycles
•
Definition: The valve cycle limit has been exceeded.
•
Implications: Each cycle represents two reversals of the direction of
valve movement. The cycle counting criterion and count limit are set by
the user to track the usage of the valve.
•
Possible Solutions: Follow routine procedures for maintenance when
the limit is reached such as checking the packing tightness, and