YSI 600DW-B Sonde - Manual (Page 297)

Frequently Asked Questions About YSI Drinking Water Systems Appendix H
Study 3 – All Data
Study 3 Expansion
How often should I check the accuracy of and/or recalibrate the free chlorine sensor?
You should confirm the accuracy of your free chlorine readings relative to a DPD colorimetric analysis
within one week of your deployment and as often as possible thereafter. Calibration checks involve
making a visit to the deployment site, performing a DPD colorimetric test of the flow cell effluent with a
handheld, battery-powered colorimeter and recalibrating the sensor if significant drift is evident. It is
important to note that because the free chlorine sensor is calibrated in situ, i.e., in flowing water in the flow
cell, the sonde setup at the site need not be disturbed, making the recalibration procedure very quick and
easy. If drift in the same direction continues to be observed, if calibration errors are evident during the
calibration process, and/or if the free chlorine readings become jumpy, then you should remove the free
chlorine probe from the sonde, recondition it, install a new membrane, and activate the sensor as described
in Section 2.6.1 of the Drinking Water Sonde Manual.
YSI Incorporated Drinking Water Monitoring Systems Operations Manual H-11