Hach Flo-Dar Sensor Basic User Manual page 22

Figure 17 Vertical alignment with extended range sensor
1 Spacer
5.1.3 Measure the sensor offset
The sensor offset is the distance from the top of the frame to the bottom of the pipe or channel. This
distance will be entered into the software and is necessary for accurate flow calculations.
If the optional extended range sensor is installed on the wall without the extended frame, the sensor
offset is the distance from the surface of the extended range sensor to the bottom of the pipe or
channel.
Items to collect:
• Rod
• Tape measure
1. Put the rod in the bottom of the pipe or channel and align it vertically with the frame. Refer to
Figure 18.
2. Make a mark on the rod to identify the location of the top of the sensor frame.
3. Measure the distance from the bottom of the rod to the mark. This is the sensor offset.
Note: If it is not practical to measure to the bottom of the pipe, measure the distance from the crown of the pipe
to the top of the frame. Refer to
Sensor offset = pipe diameter + distance from crown of the pipe to the top of the frame
22 English
Figure 18. Add this distance to the pipe diameter to get the sensor offset.