YSI APPENDIX F - Manual (Page 4)

Quick Start Guide to Drinking Water Studies Appendix F
• Immediately calibrate the free chlorine sensor in the sonde to the value just determined
via DPD analysis. Interface to the sonde for calibration can be via PC, YSI 650
Display/Logger, or YSI 6500 Process Monitor.
• Start a Continuous Monitoring Study
• For stand-alone applications, make sure that you have new batteries in your sonde and use a
PC or 650 interface to set up an Unattended Sampling Study from the Run|Unattended menu
at your desired sample interval and start the study. Under these conditions, data will be
logged to the internal memory of the sonde for later upload using a computer or a 650
display/logger. The Sample and Hold feature found in the Advanced|Setup menu of the
sonde should be INACTIVE for this type of application.
• For applications involving the YSI 6500 Process Monitor applications, follow the procedure
below. Consult Appendix G, Using Your DW Sonde with the 6500 Process Monitor or
the manual supplied with the 6500 for more details:
1. Make sure that the sonde is attached to the 6500 via a suitable YSI field cable.
2. Make sure that the 6500 is attached to line power.
3. Make sure that readings of all appropriate parameters are displayed on the screen.
4. Connect the 4-20 mA current loop or modbus outputs of the 6500 to your SCADA
system and assure proper data capture by the SCADA system.
5. Determine whether you would like the readings output to your SCADA system to be
continuous (NOT RECOMMENDED because higher frequency of free chlorine probe
maintenance and potential compromise of pH/ORP sensor life) or frozen between longer
sample intervals (RECOMMENDED because of lower frequency of free chlorine probe
maintenance and longer pH/ORP probe life).
6. If you choose continuous output to the SCADA, no further action is required.
7. If you choose to use the recommended longer sample intervals, then enter the secondary
menu of the 6500 by pressing the Esc and Enter keys simultaneously. Select Setup
sonde from the menu and (a) activate the Data Freeze and Release function by pressing
Enter to show a check mark in the box and (b) choose the sample interval between
readings, pressing Enter after selecting the interval.
8. Data should now be acquired by your SCADA system for processing according to user
software.
Maintenance of the Chlorine Sensor During a Continuous Monitoring Study
• Inspect the flow cell, inlet and drain fittings and hose attachment points as often as possible and
make certain no leaks are present. If leaks are observed, turn off the water at the inlet valve and
make the necessary repairs to the fittings and/or tubing.
• Check the accuracy of the free chlorine sensor after approximately 2 days of deployment in
flowing tap water and recalibrate the sensor to remove any drift due to long-term break-in. The
accuracy check should be done by carrying out a colorimetric DPD analysis of a sample of the
flow cell effluent and comparing it with the latest logged reading or the reading displayed in a
real-time or 6500 study. Note that the sonde should not be taken off-line to calibrate the sensor.
Calibration of any parameters during a study will not interrupt the continuity of the Unattended
logging file.
• Check the accuracy of the free chlorine sensor every two weeks if possible and recalibrate if
necessary.
YSI Incorporated Drinking Water Monitoring Systems Operations Manual F-4