Hach PHC725 - Add Kcl Crystals to the Probe

8.3 Add KCl crystals to the probe
The filling solution in the probe contains crystals of potassium chloride (KCl) that keeps the filling
solution saturated with KCl. When the sample temperature is more than 60 °C (140 °F), more
crystals are necessary to keep the solution saturated with KCl. Add more KCl crystals when the level
of crystals above the glass bulb is less than 0.5 cm (0.2 in.), or when the sample temperature is more
than 60 °C (140 °F). Refer to Figure 5 and Table 2 for preparation. Mix some of the filling solution
with the crystals to help move the crystals through the filling hole. Refer to Figure 6.
Figure 5 Items to collect
1 Plastic pipet 4 Mixing bottle
2 Measuring scoop 5 Saturated KCl solution
3 KCl crystals
Table 2 KCl quantity at high temperatures
Temperature KCl quantity
60 °C (140 °F) 0.5 g (0.5 cm (0.2 in.))
70 °C (158 °F) 0.625 g
80 °C (176 °F) 0.750 g
90 °C (194 °F) 0.875 g
100 °C (212 °F) 1.0 g (1.0 cm)
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