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 Residual
Chlorine
The measurement uses sensors with measuring electrodes in an
inside electrolyte chamber that are separated from the medium
by a membrane. The membrane-covered sensor consists of a cathode
serving as the working electrode, and an anode acting as the
counter electrode. These electrodes are immersed in an electrolyte.
Electrodes and electrolyte are separated from the medium to
be measured by a membrane. This membrane prevents the loss of
electrolyte and penetration of contaminants, which can cause
"poisoning." A fixed polarization voltage is applied
between the anode and the cathode. Free chlorine or chlorine
dioxide diffuses through the membrane and generates a signal
current in the sensor that is proportional to the content in
the medium. The signal current is transformed and displayed
on the measuring instrument as content in mg/l. For calibration,
the colorimetric or photometric measurement according to the
DPD method is used.
Amperometric
Residual Chlorine
A liquid sample liquid is delivered to the annular space between
the two fixed electrodes in the sensing cell. As it passes,
a small DC current is generated in direct linear proportion
to the amount of residual present in the sample. The residual
value is displayed on the digital indicator in mg/l (ppm). A
suitable temperature sensing element compensates for sample
temperature variation. A liquid reagent (Foxcroft- standard
food grade vinegar) is continuously added to the sample to maintain
the pH levels. The sample after analysis is drained out.
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