IM 50.560CA UA (B/4-03) 53
DEPOLOX
®
3 PLUS RESIDUAL ANALYZER
• To store the sensors after use:
Remove the elastomer seal from the vent hole. Unscrew the mem-
brane cap. Rinse the membrane and the reference electrode with dis-
tilled water. Carefully dry the reference electrode with a paper towel.
Let the cap dry in a dust free place. Screw the dry membrane cap
loosely onto the sensor. The membrane must not touch the gold work-
ing electrode.
3.4.3 Membrane Sensor Theory of Operation
• TC1: The Membrane Sensor Kit consists of a flow through cell with
a transparent Plexi-glass body that houses the chlorine sensors (and
optionally the pH or the fluoride sensor). The cell’s transparency per-
mits visual checks on the flow of sample water and measuring condi-
tions.
The Membrane Sensor measures the sum of free chlorine and chloram-
ines. The Sensor includes a membrane-covered potentiostatic 3 elec-
trode system. The silver/silver-iodide reference electrode and gold
working electrode are positioned inside the membrane cap filled with
a potassium iodide electrolyte solution. The stainless steel counter
electrode is located outside the membrane cap for added stability.
Chlorine, diffusing through the membrane, causes a reaction at the
working electrode, creating a current, which is a direct measure of
Total Chlorine. An amplifier in the electrode shaft conditions this
signal including temperature compensation and passes it to the micro-
processor-based electronic system DEPOLOX 3 plus for processing.
Air bubbles on the membrane may prevent chlorine from passing
through the membrane, resulting in a false reading of the probe. A
water jet, designed into the flow block assembly, is used to remove
any potential air bubbles from the membrane.
The sensor has a very low dependence on pH-value, so you can use
it in water with varying pH-value. The sensor should be used only in
potable water applications.
The sensor is designed such that a zero residual chlorine will yield
zero current. Therefore only a single point calibration is needed.
The flow block assembly, housing the Membrane Sensor, is designed
to provide a constant flow of water past the membrane surface. This
and the potentiostatic three-electrode system ensure accurate and re-
peatable measured data.
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