Can I Use the Zirkon® DIS Total Chlorine Sensor to Measure Free Chlorine at High pH Values?

Yes, you can use the Zirkon® DIS Total Chlorine sensor for this, if your application is drinking water and the water is free of organic substances.

Water treatment with bleach leads to almost no formation of organic chlorine, which results in the measured "Total Chlorine" consisting of almost 100% free chlorine.

A free chlorine sensor can only be used up to pH 8 since it only responds to hypochlorous acid. The Zirkon® DIS Total Chlorine sensor also responds to hypochlorite and thus can be used as high as pH 10.

Note: Calibrate against DPD1 (free chlorine).