Setting The Invisible Range - Sigma 980 Operating And Maintenance Manual

Section 4

4.10.4.3 Setting the Invisible Range

Figure 36 Setting the Invisible Range
A
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A. Minimum Distance (must be at least 11 inches (29 cm)
B. Invisible Range (set to ignore tops of channel walls)
Page 86
Downlook Ultrasonic Sensor
4. Enter the ambient air temperature at the transducer location. For optimum
results, allow enough time (100 minutes) to ensure that the sensor is at
equilibrium with the surrounding ambient temperature. Press the
soft key to continue.
5. Select the Sensor Height method and enter the new level.
6. Enter the distance from the face of the transducer to the zero flow point of
the primary device.
7. Press the soft key when finished.
ACCEPT
The 980 Flow Meter is equipped with an Invisible Range feature (adjustable
deadband) to prevent false echoes from tops of channel walls, ladder rungs,
shelves, etc. Refer to Figure
invisible to the flow meter. Extend the invisible range to where it meets or
overlaps the highest expected level in the channel. A gap of at least 2 in.
(5 cm) should be left between the invisible range and the highest expected
level. Only objects beyond the invisible range can be detected.
1. From the Main Menu, select
OPTIONS>CALIBRATION>ULTRASONIC SENSOR.
2. Select the Invisible Range option using the up and down arrow soft keys.
Press to continue.
SELECT
3. Enter the Distance to End of the Invisible Range using the numeric
keypad.
4. Select either inches or centimeters using the
distance must be greater than the minimum deadband of 11.5 in. (29 cm)
for the 75 kHz transducer. Refer to
5. Press soft key when finished.
ACCEPT
C. Highest expected water level
D. Maximum Range
36. A user-selected range is defined which is
OPTIONS>ADVANCED
CHANGE UNITS
Figure 36.
B
C
ACCEPT
soft key. The
D