Digital sensor with Memosens technology for determining free chlorine
Membrane-covered amperometric sensor for process and drinking water applications
Oxidants such as chlorine or inorganic chlorine compounds are used to disinfect water. They must be dosed immediately, depending on the operating conditions. If the concentrations are too low, this could jeopardize the disinfection process. On the
other hand, concentrations which are too high can cause
corrosion, skin irritation and affect the taste of the water.
The CCS142D chlorine sensor is used to measure free chlorine in the following areas:
- Drinking water
- Process water
- Industrial water treatment
- Sensor with digital signal processing:
- Not sensitive to electromagnetic interference thanks to digital communication with the transmitter
- Calibration data saved in the sensor, making it possible to calibrate at any transmitter or location and install subsequently at the measuring point
- Ultimate measuring reliability:
- Measurement practically independent of the flow at flow velocities above 15 cm/s (~0.5 ft/s)
- Long calibration and maintenance intervals
- No change in measured value in the event of fluctuations in conductivity
- Membrane-covered sensor, therefore:
- Easy membrane replacement thanks to prefabricated membrane head
- Minimum maintenance
- Zero-point calibration not required. No complex installation of an activated carbon filter, as found with open chlorine sensors
The concentration of free chlorine is determined according to the amperometric measuring principle. The
hypochlorous acid (HOCl) contained in the medium diffuses through the sensor membrane and is reduced to
chloride ions (Cl - ) on the gold cathode. On the silver anode, silver is oxidized to silver chloride. The electron
release of the gold cathode and electron acceptance on the silver anode result in a current flow which is
proportional to the free chlorine concentration in the medium under constant conditions. The concentration
of hypochlorous acid in the medium depends on the pH value. This dependence can be compensated by
measuring the pH value in the flow assembly.
The transmitter transforms the current signal into the measuring unit concentration in mg/l.
The membrane-covered sensor CCS142D consists of a cathode (working electrode) and an anode
(counterelectrode) in an electrolyte which is separated from the medium by a membrane. The membrane
prevents the electrolyte from leaking and protects against contaminant penetration.
The measuring system is calibrated by determining the free chlorine based on the DPD method (photometric
method). The calibration value determined is entered in the transmitter.
A complete measuring system consists of:
- A CCS142D chlorine sensor
- An assembly, e.g. Flowfit CCA250
- A Memosens data cable CYK10
- A transmitter, e.g. Liquiline CM44x
- RM junction box for cable extension
- When using the assembly CCA250: additional sensor(s), e.g. pH sensor CPS71D