Process Unit 73 LF - Knick

Concentration Measurement (Opt. 359, 382)
Concentration ranges
Substance Concentration ranges
HNO 3 0 to 30
–20 to 50
35 to 96
–20 to 50
HCl 0 to 18
22 to 39
–20 to 50
–20 to 50
H 2 SO 3) 4 0 to 30
32 to 84
–17.8 to 110 –17.8 to 115.6
NaOH 4) 0 to 14
18 to 50
0 to 100
0 to 100
NaCl 0 to 26
0 to 100
3) Range limits based on 27 5C 4) Range limits based on 25 5C
92 to 99
–17.8 to 115.6
% by wt.
C
% by wt.
C
% by wt.
C
% by wt.
C
% by wt.
C
Concentration Curves
The concentration curves of many substances show a maximum. This means that if the substance
concentration continues to increase and the temperature remains constant, the conductivity will drop.
The curve is temperature-dependent.
For sulfuric acid, the position of the maximum concentration shifts in dependence on the temperature.
Near the maximum (or near the minimum as for sulfur), the curve is so flat that the conductivity hardly
changes over a large concentration range.
This means that practical concentration determination is only possible in some areas:
In the shaded areas of the concentration curves no concentration calculation is possible.
Due to the ambiguity of the curves (the same conductivity may correspond to several concentration
values), the measuring range of the concentration must be defined.
Specifications 14–13