Data
70
J
Sample liquid conditions
Q
Influence of the pH of the sample
The chemical form of free residual chlorine varies depending on the pH of the sample, as
described in the previous section.
Fig. 3 indicates variations in the readings of the converter due to a change in the pH values.
As indicated in Fig. 3, the readings decrease as the sample changes from acid to alkali. Fig. 3
indicates a change in the readings when calibration is performed using a pH 7 sample. If the
pH of the sample has changed largely from that during calibration, it affects the readings. In
order to avoid this, be sure the pH of the sample is as stable as possible.
Fig. 3 Change in readings due to a change in pH of the sample
Q
Influence of the conductivity of the sample
The converter performs measurement of the free residual chlorine concentration using
electrochemical reactions.
Therefore, if the conductivity of the sample is low, it could affect the readings (Fig. 4).
Adjust the conductivity of the sample above 100
μ
S/cm before passing it through the
measuring cell. However, there should be generally no problem when tap water or swimming
pool water is used, as the conductivity of these types of water is already above 100
μ
S/cm.
Fig. 4 Change in readings due to a change in the conductivity of the sample
5.5 6 6.5 7 7.5 8 8.5 9
pH
110
105
100
95
90
85
80
Percen
ta
g
e at
pH
7
.0 [
%
]
Conductivity of the sample [uS/cm]
Residu
al chlo
rine conce
ntra
tion [mg
/L
]