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Downlook Ultrasonic Sensor
Section 4
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
ACCEPT
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
ACCEPT soft key when finished.
4.10.4.3 Setting the Invisible Range
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 36. A user-selected range is defined which is
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>ADVANCED
OPTIONS>CALIBRATION>ULTRASONIC SENSOR.
2. Select the Invisible Range option using the up and down arrow soft keys.
Press
SELECT to continue.
3. Enter the Distance to End of the Invisible Range using the numeric
keypad.
4. Select either inches or centimeters using the
CHANGE UNITS soft key. The
distance must be greater than the minimum deadband of 11.5 in. (29 cm)
for the 75 kHz transducer. Refer to Figure 36.
5. Press
ACCEPT soft key when finished.
Figure 36 Setting the Invisible Range
A. Minimum Distance (must be at least 11 inches (29 cm) C. Highest expected water level
B. Invisible Range (set to ignore tops of channel walls) D. Maximum Range
A
B
C
D