Xylem 6-Series Multiparameter - Manual (Page 323)

Flow Appendix F
YSI Incorporated Environmental Monitoring Systems Operations Manual F-4
Deploy the sonde so that the pressure sensor on the side of the sonde is slightly below the lowest level
expected. Be sure the sonde is installed so that it cannot move during measurement.
Normally, a staff gauge is installed with a weir. After the sonde is installed, calibrate depth to the value
read off the staff gauge.
Be sure also to follow the instructions printed in Appendix G, Using Vented Level.
FLUME
Generally there is a staff gauge installed in a flume at the point where the level should be measured. Be
certain that you know the location of the measurement for the flume you are using. Some flumes are built
with a stilling well outside of the flume. Deploying the sonde in the stilling well will give accurate level
readings, but readings of other parameters like DO and pH may not be equivalent to those in the main flow
of the flume. Also be aware that many flumes are not much bigger than the sonde. Installing the sonde in
the flume may change the way the flume behaves, thus causing errors in flow readings. An ideal
deployment would include a flume with a recess for the sonde that locates the pressure sensor properly,
allows the other sensors to measure the water flowing through the flume, and does not significantly alter
the geometry of the flume. In a flume this means deploying the sonde horizontally. If possible, deploy the
sonde so that the pressure sensor on the side of the sonde is slightly below the lowest level expected. Also
be aware that the pressure sensor in the sonde is along the side of the sonde and not at its very tip. If a
sonde is deployed vertically in the flume, then it may not be able to make measurements when the water
level is low. Be sure the sonde is installed so that it cannot move during measurement.
Normally, a staff gauge is installed with a flume. After the sonde is installed, calibrate depth to the value
read off the staff gauge.
Be sure to follow the instructions printed in Appendix G, Using Vented Level.
USING THE MANNING EQUATION IN AN OPEN CHANNEL
The channel should be large enough that the sonde does not significantly alter the flow of water. Most
deployments will require the sonde to be in the channel horizontally so that the pressure sensor remains
submerged at all times. Be sure that the sonde cannot move during the measurement. After installation
measure the depth of water in the channel with a ruler and use that measurement to calibrate depth on the
sonde.
Be sure to follow the instructions printed in Appendix G, Using Vented Level.