Hanna Instruments HI 9912 User Manual

Page 12

Make sure that the controller has been properly calibrated before
commencing and that the pH and ORP setpoint(s) have been
adjusted (see the following pages).
The pH and ORP electrodes and any ground probes must be properly
connected and wired to the controller (see preceding pages).
Remove the protecteive caps if they are still on the tip of the electrodes
and ensure that the electrodes are immersed in the solution (at least
4cm/1.5”). The electrodes should be in-
stalled in such a away that they
permanently lie in the solution whether in
a well, tank or on the discharge pipe.
The actual pH and ORP values will be
displayed on the LCD’s.

NORMAL OPERATION &

MEASUREMENT

8.00

650

ORP

HI 9912 provides for visual dosing status through two LED’s, one for
pH and another for ORP. The LED’s light up when the controller is in
the pH or ORP dosage mode and the terminals are activated.

500

900

SET

FEED

ALARM

OXID

700

ALARM

SET

FEED

ACID

• For 110-115V, short the L and L1 termi-

nals. Then wire the external power supply
to the three terminals as shown.

• Replace the cover with the gasket and

screw it tight with the 4 screws provided.
Only then

Only then

connect the controller to the mains.

NOTE:
HI 9912 provides for two separate relays, one for pH and another for
ORP. In order to save on chemicals and due to the slow reaction of
oxidants, the controller incorporates a Consent feature

Consent feature

Consent feature by which

ORP measurements are adjusted only after pH has been corrected.
The Consent feature makes the pH correction

pH correction

pH correction the master

master

master and the

ORP adjustment

ORP adjustment the salve

salve

salve for a better control.