Hach-Lange PHC745 - Manual (Page 3)

6. For Red Rod probes, make sure that there is approximately 0.5 cm (0.2 in.) of KCl
crystals in the filling solution in the probe. Refer to Table 1 . For measurements at
temperatures higher than 60 °C (140 °F), add KCl crystals through the filling hole.
Refer to
Table 1 to calculate the quantity of KCl crystals to add. The quantity of
necessary KCl crystal increases linearly from 60 to 100 °C.
7. For Red Rod probes, make sure that the KCl crystals move freely through the liquid
when the probe is inverted. If necessary, shake the probe to loosen the crystals.
8. Make sure that the sleeve junction is open before calibration or measurement (refer
to Sleeve junction on page 3).
9. Make sure that the filling hole is open during measurement for the correct flow of the
filling solution.
Note: For the best stabilization time, condition the probe for 2 hours in pH buffer 4.01 before use, if
the probe was not used for 3 weeks or more. In low ionic strength (LIS) samples, condition the
probe for a maximum of 5 minutes in the sample before use. In all other cases a condition before
use is not necessary.
Figure 2 Filling solution level
1 KCl crystals 1 3 Filling solution
2 Filling solution level 4 Standard solution or sample level
1 Red Rod probes only
Table 1 KCl crystal level for Red Rod pH probes
Temperature Amount of KCl crystals Add Temperature Amount of KCl crystals Add
60 °C (158 °F) 0.5 g (0.5 cm) 0 g 90 °C (194 °F) 0.875 g 0.375 g
70 °C (158 °F) 0.625 g 0.125 g 100 °C (212 °F) 1.0 g (1.0 cm) 0.5 g
80 °C (176 °F) 0.750 g 0.25 g
Sleeve junction
The sleeve junction must be open during calibration and measurement for a correct
electrical contact between the inner electrolyte and the standard or sample. Adjust the
sleeve junction to change the flow of electrolyte. A higher flow of electrolyte can result in
better speed of response in different sample types.
1. Hold the probe over a beaker or container.
2. Lift the sleeve junction until some drops of electrolyte flow out.
3