EB 8389-1S EN 27
Valve signature
4 Valve signature
The valve signature plots the signal pressure
p
out
as a function of valve position x.
All diagnostic functions dependent on the
signal pressure are based on the valve sig-
nature, e.g. to detect pneumatic leakage or
to reveal an excessively high or low supply
pressure.
Note:
Additionally, the pneumatics are mon-
itored using the 'Leakage limit' param
-
eter, which is adjustable between 0
and 100% in the Device settings fold-
er (> Alarm settings). The positioner
generates the 'Pneumatic leakage'
message whenever the leakage ex
-
ceeds this limit value. 'No message' is
assigned by default.
Requirements
1. A single-acting actuator is mounted on
the valve.
2. The valve operates as a control valve.
1.
Device settings > Actuator
− Principle of operation (Code 48 - d11):
Single-acting
2.
Start-up
− Type of application (Code 49 - h0):
Control valve
To perform monitoring while the process is
running, the reference graph must rst be
plotted.
Fig. 2: Start-up > Reference graphs > Valve signature
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