Hanna Instruments HI 8614 - Manual (Page 13)

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INSTALLATION PROCEDURE
AND EXAMPLES
The HI 8614, HI 8614L, HI 8615 and HI 8615L
transmitters may be wall mounted in any con-
venient location near the measurement point.
To minimize thermal drift due to extreme tem-
perature fluctuations during the measurement
process, particularly if the measurement is
conducted outdoors, it is best to protect the
transmitter in an enclosed casing.
General Installation Procedure
For most industrial application involving long
term monitoring and control, it is also recom-
mended to use tank electrode holders (HI 6050
or HI 6051) to protect the pH electrode and the
temperature probe from contamination by the
test solution.
Controlling the pH / ORP with a recorder
Typical Electrode Life
Ambient Temperature 1- 3 years
90 °C Less than 4 months
120°C Less than 1 month
High concentrations of sodium ions interfere
with readings in alkaline solutions; the pH at
which the interference starts to be significant
depends upon the composition of the glass.
This interference is the alkaline error and
causes the pH to be underestimated. Hanna's
glass formulations have the indicated charac-
teristics.
Alkaline Error
1.0 Mol L -1 Na +
0.1 Mol L -1 Na +
Sodium Ion Correction for the Glass
at 20-25°C
Concentration pH Error
13.00
13.50
14.00
12.50
13.00
13.50
14.00 0.10
0.14
0.20
0.10
0.18
0.29
0.40