Appendix A: Technical reference
A.2 Echo Processing
SITRANS LR250 with mA/HART
240 Operating Instructions, 10/2019, A5E32220602-AG
A.2.7 Measurement Range
Near Range (2.8.1.)
Near Range programs SITRANS LR250 to ignore the zone in front of the antenna. The
default blanking distance is 50 mm (1.97") from the end of the antenna.
Near Range allows you to increase the blanking value from its factory default. But Auto False
Echo Suppression (2.8.7.1.) is generally recommended in preference to extending the
blanking distance from factory values.
Far Range (2.8.2.)
Far Range can be used in applications where the base of the vessel is conical or parabolic.
A reliable echo may be available below the vessel empty distance, due to an indirect
reflection path.
Increasing Far Range to 30% or 40% can provide stable empty vessel readings.
A.2.8 Measurement Response
Note
Units are defined in Units (2.2.1.)
and are in meters by default.
Response Rate (2.4.1.) limits the maximum rate at which the display and output respond to
changes in the measurement. There are three preset options: slow, medium, and fast.
Once the real process fill/empty rate (m/s by default) is established, a response rate can be
selected that is slightly higher than the application rate. Response Rate automatically adjusts
the filters that affect the output response rate.
Fill Rate per Minute (2.4.2.)/Empty Rate per Mi-
nute (2.4.3.)
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