YSI 600DW-B Sonde - Manual (Page 43)

Sondes Section 2
Thoroughly rinse and dry the calibration cups for future use.
FREE CHLORINE 1-POINT
The 6572 free chlorine sensor MUST be calibrated in situ, i.e. in flowing drinking water whose free
chlorine content has been determined by an independent method. In many cases, the independent method
involves the use of the DPD Colorimetric Method as defined in Section 4500-Cl G of Standard Methods for
the Examination of Water and Wastewater. Relatively inexpensive colorimeters, such as the YSI Models
9000 and 9100 and the Hach Model 5870000, are available for carrying out the DPD method to determine
the free chlorine in the effluent of the flow cell associated with the 6920DW or 600DW-B drinking water
studies.
After activation of the sensor according to the instruction in Section 2.6.1 above and AFTER the calibration
of all other sensors present, reinstall the free chlorine probe in the sonde bulkhead after removing the port
plug. Make certain that no moisture is present in the port before installing the probe and, if moisture is
present from the previous calibration procedures, use compressed air to dry the port.
After installing the free chlorine sensor in the sonde bulkhead, locate the flow cell which you purchased
with your drinking water sonde and install the sonde in the flow cell according to the instruction supplied
with the flow cell and as provided below:
• Attach inlet and outlet hoses to the barbed fittings supplied with the flow cell and then insert the
fittings into the proper ports of the flow cell. Make certain that the hoses are attached very snugly
to the barb fittings to prevent any possibility of catastrophic leakage. If necessary, standard hose
clamps can be used to secure the hoses to the barbed fittings.
• Connect the inlet line of the flow cell to a drinking water tap and run the outlet line to a drain.
Make certain that the inlet line is securely attached to the tap and that the outline line will not pop
out of the drain under flow conditions.
NOTE CAREFULLY: Make certain that the inlet line is attached to the bottom fitting of the
flow cell and the drain line is attached to the top fitting.
• Turn on the water with a flow rate of 500-1000 mL/minute (500 mL/min minimum).
• Break in the sensor by running it continuously in flowing tap water by one of the following
methods:
• If using a PC with EcoWatch for sonde interface, start a Discrete Sample study at a 4 second
interval as described below and continue the study for 2-3 hours while displaying the readings
on the PC monitor.
• If using a 650 Display/Logger for sonde interface, choose the Sonde Run selection from the
Main menu and continue the study for 2-3 hours while displaying the readings on the 650
screen.
• If using a 6500 Process Monitor for sonde interface, simply allow the system to run for 2-3
hours while displaying the readings on the 6500 screen.
During the 2-3 hour break-in period, the Free Chlorine and Chlorine Charge readings should drop
significantly and show reasonable stability for periods of 5 minutes.
YSI Incorporated Drinking Water Monitoring Systems Operations Manual 2-36