Stage – Pre-disinfection, Filtration, Disinfection, Storage & Distribution
Two different technologies (amperometry, photometry) and three types of instruments are available for monitoring free chlorine, ozone, chlorine dioxide or monochloramine. The choice depends on water treatment methods:
• Amperometric three electrode system TRIDES: Treatment with free chlorine, chlorine dioxide or ozone. Dual channel system (chlorine and pH) will provide on-line conversion from hypochlorous acid to free chlorine without reagents.
• Process photometers CODES: Work under the same conditions as the amperometric system. In addition, they can be used for monochloramine. pH compensation is not necessary because the reagents contain a buffer solution.
Amperometric systems have lower cost of ownership (no reagents). Under unknown conditions (and at pH above 8.5) Swan recommends using a photometer.
• CHEMATEST portable photometer: A high precision portable photometer is needed for verification and calibration in any case.