Hanna Instruments HI 904 - Manual (Page 52)

4-6
GENERAL OPTIONS
4.5 Language
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4.6 Reagent Exchange Reminder
Coulometric Karl Fischer reagents have a limited titration capacity, meaning that there is a
limited amount of water that a volume of reagent can react. For this reason, the HI 904
automatically tracks the total amount of water that has been reacted since the reagent was
added to the titration vessel. By default, an “Exchange Reagent” reminder will appear after
1000 mg of water have been titrated.
Coulometric Karl Fischer reagents also have a tendency to produce precipitates and
foul-smelling sulfurous compounds. This is particularly problematic when using a diaphragm
generator due to the risk of clogging the diaphragm. Most reagent manufacturers recommend
changing the reagent (anolyte and catholyte) weekly regardless of the amount of use. The
HI 904 can automatically track the elapsed time since the reagent was added to the titration
vessel by setting a reminder timer.
Both reminder types (timer and water counter) are automatically reset after using the air
pump. The reminders can be manually reset by selecting the “Reset Reminder” option.