Hanna Instruments HI 8711 - Manual (Page 26)

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Examples:
For HI 8710, if the set value is pH 3 and the ΔALARM is 1.5 pH, the
instrument generates an alarm every time the pH reading is higher
than 4.5 pH or lower than 1.5 pH.
For HI 8711, if the set values are pH 7 and pH 8, and the ΔALARM is
1.5 pH, the instrument generates an alarm every time the pH reading
is higher than 9.5 pH or lower than 5.5 pH.
For HI 8720, if the set value is 300 mV and the ΔALARM is 100 mV, the
instrument generates an alarm every time the ORP reading is higher than
400 mV or lower than 200 mV.
An alarm is generated if the dosing time exceeds the overtime dosage
period set (if not disabled).
MEASUREMENTS
After setting the pH (or ORP) and alarm (if
available) thresholds, immerse the electrode in
the solution to be tested and press MEASURE.
Note: The ALK. and the ACID setpoints can be set on the entire range
0.00 pH to 14.00 pH using COARSE and FINE trimmers.
In order to avoid erroneous situations the ALK. setpoint value
should not exceed the ACID setpoint value.
ALARMS (HI 8710, HI 8711 and HI 8720)
To set the alarm tolerance, press ΔALARM key and the display will
show the current value.
Using a small screwdriver adjust the ΔALARM trimmer to display the
desired tolerance.