Badger Meter SRD/SRI Valve Positioners - Manual (Page 57)

Friction / Load Factor
The Friction is a value to determine the force / friction between the stem
and the packing during a movement .
This measurement requires the optional pressure sensors to measure the
supply pressure and the output pressure(s) .
Each time the stem or shaft moves, the positioner measures the
pressure overshoots caused by the stick-slip effect and calculates within
Milliseconds the values for the friction of the movement displayed as
the Load Factor Value .
Friction Configuration
Before an accurate friction measurement can take place, the value of the Spring Range that is listed on the valve label needs
to be entered . The Spring Range is only applicable to single-acting (spring loaded) actuators and is defined with a lower and
upper value . First select the Unit in psig, kPa or bar of how the Spring Range is defined then enter the Range . The Range is
configured as [lower value] to [higher value] psig/kPa/bar and identifies the valve movement from fully closed (for example, at
lower value 1 .5 bar) to fully open (for example, at upper value 2 .7 bar) .
In case the Spring Range is not available, it can also be determined manually after an Autostart has been executed . Select
in the LCD-Menu the display for the output-pressure . Slowly increase the setpoint to the valve and check at what output
pressure the valve starts moving (lower Spring Range) and when the valve is fully open (upper Spring Range) . This
measurement is quite accurate .
After configuration, press Save and Download .
NOTE: N After initial start-up the Load Factor Value can be very high, because the Spring Range originally could have been out
of scale . In this case click on Reset or go to Reset Valve Diagnosis and check the box for the Load Factor and press
Continue . The data in the fields for Measured Value, Minimum Value, Maximum Value will be reset .
To ensure that the reading is the actual reading, press Update .
The Load Factor Alarm Limits can be freely defined and configured . The default setting of the Load Factor Alarm Limits is at
20% increase and –20% decrease in comparison to the Reference Value . The Reference Value is set by clicking on the Set Ref.
button .
Configuration / Parameter
Page 57 August 2014 POS-UM-00011-EN-02