II. SYSTEM COMPONENT DESCRIPTION
Refer to Figure 2 for this section.
1. Measurement Cell:
The measurement electrodes consist of a cathode and a Copper anode. The
measurement electrodes are mounted in a PVC housing assembly. The electrodes are in the shape
of concentric cylinders. The cathode is the inner smaller cylinder and the anode is the outer larger
cylinder. The sample water fi lls the gap in between the electrodes and continually fl ows in the upward
direction. The detailed description of the electro-chemical process can be found in section I.
The Series 210 Residual Chlorine Analyzer also employs a continuous electrode cleaning method.
The purpose of this method is to keep the electrode surfaces clean and free of chemical desposits
to ensure consistent measurement readings. The cleaning is accomplished by fi lling the space
between the electrodes with roughly 130
7
⁄
32
" diameter PTFE cleaning balls and continuously driving
them around the annular gap with a rotary motor. These balls and the electrodes require periodic
maintenance and replacement as described in Section VI.
2. Temperature Probe:
A Thermistor is used to continuously measure the sample water Temperature.
The Temperature can be displayed and retransmitted by the Series 210 Residual Chlorine Analyzer.
It is also used in software for signal manipulation for the two following reasons:
Temperature compensation for the e
ff
ects of Thermal Di
ff
usion:
As described in Section I, the rate of
arrival at the electrode surfaces is dependent on the Temperature of the sample water. If the device
is being used at a location with constant water Temperature, then this compensation is not necessary.
However, if the sample water Temperature experiences signifi cant fl uctuations, then the raw signal
will be aff ected and software Temperature compensation is necessary for accurate readings.
For use in pH compensation:
As described in Section I, if the pH buff er is not being used to lower the
sample water pH, then pH compensation is necessary to achieve accurate measurements.
3. Optional Reagent Chemical Feed System:
The Series 210 Residual Chlorine Analyzer can be
fi tted with a mechanically driven reagent feed system. The chemical reagent solution is continuously
injected at a controlled rate by a mechanical system driven by the motor that is used to drive the
cleaning balls in the measurement cell. Section I.5 outlines the various reagent solutions that may be
needed depending on the target measurement species and the measurement method. If operating
properly, the reagent feed system should feed the solution at a rate of 3⁄4" to 11⁄8" (20 to 30 mm)
level change in 24 hours.
4. Optional pH Probe:
If the unit is not fi tted with the reagent feed system then it is recommend that
the unit be equipped with an external pH probe. This probe is mounted in its own acrylic chamber
located to the right of the measurement cell and used used to compensate for the eff ects of pH
as described in section I. It is not recommended that this compensation method be used where
the sample water being measured is consistently above pH 8.5. Should this be the case Hydro
Instruments recommends utilizing the reagent feed system.
FIGURE 2
Motor
Water
Sample
Inlet
Cleaning
Balls
Rotating
Striker
Cylindrical
Copper
Electrode
Probe
Screen
Drain
Electrical
Signal
Overflow
to Drain
Rotary Valve
Buffer Chemical Feed
6
Содержание 210 Series
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