Hach Ultra POLYMETRON 9210, Operator'S Manual, Page: 12 / 116

Page 6
SILKOSTAT 9210
Operation
The 9210 can analyse up to six different samples. The sample to be
analysed circulates in a fast loop permitting rapid renewal of the sample.
Adjustment of the flow is carried out with the help of a needle valve (2). At
the beginning of the analysis, the sample is introduced into the
measurement cell (4) with the help of a solenoid valve (5).
The 1
st
reagent is added with the pump (9). The silica contained in the
sample now reacts with the molydate and forms the silicomolybdic
complex. The reagent time is relatively long.
Oxalic acid is then added to avoid the interference of phosphates and to
intensify the colour.
The silicomolybdic complex is reduced to a blue molybdenum complex by
means of ferrous ions. A photometric measurement is carried out at the
end of the reaction.
Figure 2 Working principal
1 - Overflow tank with level detector
2 - Flow adjustment valve
3 - Sample input 1 to 6
4 - Photometric measurement cell
5 - Measuring solenoid valve 6 - Mixing motor
7 - Magnetic bar
8 - Drain
9 - Reagent pump 10 - Calibration solution canister
11 - Calibration pump
12 - Photometer
13 - Drain pump of measurement cell
Calibration
In order to ensure correct functioning, the analyser should be calibrated
periodically. The zero is realised chemically and internally in the analyser.
The system slope is controlled in comparison to a standard solution of
known concentration.
8
10
3
3
3
3
3
3
1
8
4
7
5
11
13
12
9
2
6