Liquid Depth; Sensor Height - Sigma 980 Operating And Maintenance Manual

4.11.4.1 Liquid Depth

4.11.4.2 Sensor Height

2. Highlight Calibration, using the up and down arrow soft keys. Press the
soft key to continue.
SELECT
3. Highlight Ultra-Sonic Sensor, using the up and down arrow soft keys.
Press the soft key to continue.
SELECT
4. Highlight Calibrate U-Sonic Sensor and press the
5. Select the type of ultrasonic transducer (In-Pipe), using the
soft key.
CHOICE
6. Press the soft key.
ACCEPT
7. 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.
The speed of sound in air varies with the temperature of the air. The ultrasonic
sensor is equipped with temperature compensation to help eliminate the
effect of temperature variation under normal site conditions.
8. Press the soft key to continue.
ACCEPT
Liquid depth requires knowing the level or depth of the liquid in the channel
that is contributing to flow. Liquid depth calibration is the recommended
calibration method for the in-pipe ultrasonic sensor.
Continue from Step 8, above:
1. Select the Liquid Depth method.
2. Take a physical measurement of the liquid depth (head) and enter the
value.
3. Press the soft key when finished.
ACCEPT
Sensor height calibration is generally used when access to the primary device
is difficult (such as confined space entry in a manhole) or when there is no
liquid flowing during installation of the flow meter. This calibration method
requires compensation for the internal deadband in the sensor housing.
Measurement uncertainty increases to 0.85 m (0.028 ft) for a 60 cm (2 ft)
change in level from the calibration point. Use this method only if the Liquid
Depth method is not an option.
Continue from Step 8, above:
1. Measure the distance from the bottom of the sensor to the zero flow point.
Add 18.2 cm (7.17 in.) to the measured distance to obtain the total zero
flow distance for the in-pipe sensor. Refer to Manual Figure Side View of
In-Pipe on page 4 of this change notice.
2. Select the Sensor Height calibration method and enter the total zero flow
distance from Step 1.
3. Press the soft key when finished.
ACCEPT
Section 4
soft key.
SELECT
CHANGE
Page 89
In-Pipe Ultrasonic Sensor