Hanna Instruments HI 9914 - Manual (Page 13)

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• Turn the SET knob until the display shows the desired value.
•Turn back in measurement mode by pressing the MEA button.
Note: The internal pH and EC regulators have a small hysteresis to
prevent oscillations of the relay output that can damage the
pumps. As a result, the selected pH and EC values are equal to
the set value ± hysteresis value.
SETTING EC AND pH CONTROL TIMERS
The Timer feature is provided to avoid overdosing in a system with a long
response time. The running time of the dosing pumps is set through the
TIMER knob. The total time frame is 15 minutes. For example, if the
TIMER is set to 3 minutes, the EC or pH correction pumps will be active for
3 minutes and off for 12 minutes (3+12=15 minutes).
Setting the timer:
• In order to activate the timed dosing feature put the TIMED/CONT
switch to the TIMED position.
• To set the duty cycle of the dosing
pumps, turn the TIMER knob to the
desired position, from 1 to 10 minutes,
depending on the tank volume.
When the TIMED/CONT switch is at the CONT position, the EC and pH
correction pumps will run continuously.
SETTING THE CIRCULATION PUMP WORKING REGIME
• Set the CONT/PAUSE switch to CONT to enable a continuous running
of the Circulation pump (if no ALARM condition is present).
• Set the CONT/PAUSE switch to PAUSE to stop the Circulation pump
after the good water composition is reached (do not run the Step 5).
The pump will start again when an adjustment of water composition
is needed or the irrigation takes place.