Hanna Instruments hi 9914 User Manual

20

Step 4:
The water nozzle is closed, circulation pump is running and the Conduc-
tivity & pH controls are activated. The Conductivity control has the
priority over the pH control.
• If the timer feature is activated, the control is on for a selected period

(1-10 minutes) and off for the remaining period until 15 minutes.

• If both the conductivity and pH values are good for at least 30

seconds, the controller goes to step 5.

• If the normal level sensor remains open for about 15 minutes, the

controller goes back to step 3.

Step 5:
The Conductivity & pH values are good. The Circulation pump is running
and the controller waits for user input. This state is signaled on the front
panel by 

FEED OK LED and externally through a 15mA current between

the 

FEED OK and INPUT COMMON pins.

• If the water composition is not good, the controller goes back to step 4.
• If the normal level sensor remains open for about 15 minutes, the

controller goes back to step 3.

• If the FILL button (or the external fill button connected between 

FILL

and 

INPUT COMMON) is pressed while the NORMAL LEVEL sensor is

open, then the controller goes back to step 3.

• If the user input command is active (the contact is closed between the

USER INPUT and INPUT COMMON pins), the controller goes to step 6.

Step 6:
The Feeding pump is activated. The control of Conductivity and pH is
inhibited.
• If the user input becomes inactive (the contact between the 

USER

INPUT and INPUT COMMON pins is open), the controller goes back
to step 3.

• If the low level is reached (the low-level sensor contact  is open), the

controller goes back to step 3.

• If the water remains under normal level for about 15 minutes (the

normal level contact is open), the controller goes back to step 3.

The tank can also be filled by pressing the 

FILL button on the front panel

(or the external fill button connected between 

FILL and INPUT COMMON

pins) when the irrigation is completed.