Hanna Instruments HI 9912 User manual

Instruction Manual
HI 9912
Wall Mounted
Dual pH/ORP
Controller
http://www.hannainst.com These Instruments are in
Compliance with the CE Directives
ALARM
LINE
SETORP
SETpH
0SECONDS
mV2000
ORP
TIMER
MINUTES
90
PROPORTIONALSETTINGS
1
10
2.5
57.5
0SECONDS
pH2.00
pH
TIMER
MINUTES
90
PROPORTIONALSETTINGS
1
10
2.5
57.5
10050
CAL
ALARM
ON
OFF
50150
SET
RDX
mV
OFFSETSLOPE
ALARM
ON
OFF
0.51.5
pH
HI 99
mV
ORP
3
SET
ACID
AL
2
FE
300
pH
0
1
2
0
100
200
mV
ALARM

2
TABLE OF CONTENTSTABLE OF CONTENTS
TABLE OF CONTENTSTABLE OF CONTENTS
TABLE OF CONTENTS
Dear Customer,
Thank you for choosing a Hanna Product.
Please read this instruction manual carefully before using the instru-
ment. This manual will provide you with the necessary information for
a correct use of the instrument, as well as a more precise idea of its
versatility. If you need more technical information, do not hesitate to
e-mail us at [email protected].
These instruments are in compliance with the directives.
PRELIMINARY EXAMINATION ........................................................ 3
GENERAL DESCRIPTION ................................................................ 3
MECHANICAL LAYOUTS................................................................. 4
FUNCTIONAL DIAGRAM ................................................................ 6
CONNECTIONS & WIRING ............................................................ 9
NORMAL OPERATION & MEASUREMENT ..................................... 12
pH CALIBRATION ....................................................................... 13
ORP CALIBRATION ..................................................................... 14
ADJUSTEMENT OF SETPOINT(S) .................................................. 15
PROPORTIONAL CONTROL.......................................................... 15
OVERDOSAGE TIMERS ................................................................ 17
pH VALUES AT VARIOUS TEMPERATURES ................................... 18
REDOX MEASUREMENT ............................................................... 19
ELECTRODE CONDITIONING & MAINTENANCE ............................... 20
SUGGESTED INSTALLATIONS FOR pH/ORP ELECTRODES ............... 21
ACCESSORIES ............................................................................. 22
WARRANTY ................................................................................ 25
OTHER PRODUCTS FROM HANNA ............................................... 26
CE DECLARATION OF CONFORMITY.............................................. 27

3
PRELIMINARY EXAMINATIONPRELIMINARY EXAMINATION
PRELIMINARY EXAMINATIONPRELIMINARY EXAMINATION
PRELIMINARY EXAMINATION
GENERAL DESCRIPTIONGENERAL DESCRIPTION
GENERAL DESCRIPTIONGENERAL DESCRIPTION
GENERAL DESCRIPTION
Remove the instrument from the packing material and examine it
carefully to make sure that no damage has occurred during shipping.
If there is any noticeable damage, notify your Dealer.
Note: Save all packing materials until you are sure that the
instrument functions correctly. Any defective item must be
returned in the original packaging together with the supplied
accessories.
IMPORTANT:
1. Read the instructions before using the instrument.
2. The instrument should be connected to a mains socket.
3. Never install the controller outdoors, in a wet or humid area or
under direct sun light. Nor install the controller where liquids may
be sprayed or poured on it.
4. The instrument’s main power line as well as the dosage and
alarm terminals are protected by separate 2A fuses. Use only 2A
fuses for replacement.
Hanna's wall-mounted pH and ORP controller with proportional
control is designed to meet a variety of process control requirements,
especially those in swimming pools and water conditioning.
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 by which ORP
measurements are adjusted only after pH has been corrected. The
Consent feature makes the pH correction the master and the ORP
adjustment the salve for a better control.
The electrodes can be installed quickly and easily. Simply plug the
universal BNC connectors into the sockets and twist them into a
secured position. Accurate measurements are displayed on large
LCD’s.
In order to avoid electrical noise and interference, HI 9912 provides
for two ground probes (differential inputs.
The controllers come equipped with relays operating at a maximum of
2A (240V).

4
pH
0
1
2
0
100
200
mV
ALARM
pH
0SECONDS
mV 200 0
TIMER
MINUTES
90
PROPORTIONALSETTINGS
110
2.5 57.5
0SECONDS
pH 2.0 0
TIMER
MINUTES
90
PROPORTIONALSETTINGS
110
2.5 57.5
500 900
CAL
ALARM
ON
OFF
SET
FEED
mV
OFFSET SLOPE
ALARM
ON
OFF
0.5 1.5
pH
HI 9912
mV
ORP
ALARM
8
SET
FEED
ALARM
6
7
ACID
OXID
700
50 150
SET pH
SET ORP
ALARM
LINE
LCD DISPLAY
CALIBRATION
TRIMMERS
CONTROL KNOBS
AND SWICHES
OUTPUT TERMINALS
DOSING TERMINALS
POWER SUPPLY
TERMINALS
ALARM CONTACTS
MATCHING PIN
Fig. 2
Figure 2 illustrates the controls and terminals.
MECHANICAL LAYOUTSMECHANICAL LAYOUTS
MECHANICAL LAYOUTSMECHANICAL LAYOUTS
MECHANICAL LAYOUTS
ELECTRODE WITH
BNC CONNECTION
WIRING ACCESS
PORTS
MATCHING PIN FOR GROUND PROBE
Fig. 1
The Hanna controllers incorporate a triple contact alarm system.
When activated, the alarm contacts will open or close, triggering the
mechanism of your choice, whether a buzzer, light or any other
electrical device.
The controller is housed in a rugged, modular, fiber-reinforced ABS
housing.
All models can be wired to work with 110/115V or 220/240V
50/60 Hz power supplies.
Figure 1 illustrates the connectors for electrodes and the wiring access
ports.

5
3.8“
96.9 mm
25 mm
1“
75 mm
3“
Fig. 3
227.8 mm
9“
188.6 mm
7.4“
221.8 mm
8.7“
174.8 mm
6.9“
Fig. 4
Figure 3 is a dimensioned, bottom view of the Wall Mounted
Controller. The modular design isolates the control circuitry from the
contacts making it possible to make the connections and then close
the compartment. Adjustments can then be made only in the control
area, without having to open the contacts compartment.
Figure 4 is a dimensioned front view of the Wall Mounted Controller.
The molded, mounting holes in the corners provide for quick and
secure installation. No additional hardware is needed for mounting.
All electrical connections and controls are located on the front of the
instrument so that adjustment can be made without having to
remove the unit.

6
FUNCTIONAL DIAGRAM HI 9912FUNCTIONAL DIAGRAM HI 9912
FUNCTIONAL DIAGRAM HI 9912FUNCTIONAL DIAGRAM HI 9912
FUNCTIONAL DIAGRAM HI 9912
pH
0
1
2
0
100
200
mV
ALARM
pH
0SECONDS
mV 200 0
TIMER
MINUTES
90
PROPORTIONAL SETTINGS
110
2.5 57.5
0SECONDS
pH 2.0 0
TIMER
MINUTES
90
PROPORTIONAL SETTINGS
110
2.5 57.5
500 900
CAL
ALARM
ON
OFF
SET
FEED
mV
OFFSET SLOPE
ALARM
ON
OFF
0.5 1.5
pH
HI 9912
mV
ORP
ALARM
8
SET
FEED
ALARM
6
7
ACID
OXID
700
50 150
SET pH
SET ORP
ALARM
LINE
1
3
4
5
6
7
8
9
10
11
12
14
13
15
16
17
18
19
20
21
2
2
4
822
FRONT PANEL
Left panel
1. Alarm LED signal for pH
2. Liquid Crystal Displays for pH and ORP
3. Acid feed LED and dial to adjust the pH setpoint
4. Alarm disable switches for pH and ORP
5. Slope calibration trimmer for pH
6. Offset calibration trimmer for pH
7. Proportional pH band and time cycle settings
8. Two independent maximum dosage timers
9. Alarm LED for mV (ORP)
10. Calibration trimmer for mV
11. Oxidant feed LED and dial to adjust the ORP setpoint
12. Proportional mV band and time cycle settings
Right panel
13. pH alarm setting from 0 to 2 pH
14. Short the terminals if a pH ground probe is not in use, or
connect the ground probe wire to the Matching Pin terminal
15. Short the terminals if an ORP ground probe is not in use, or
connect the ground probe wire to the Matching Pin terminal
16. ORP alarm setting from 0 to 200 mV

7
Unplug the instrument from the power supply before
wiring or replacing the fuses.
23 2425 26
17. Triple contact alarm in a Normally Closed (NC) or a Normally
Open (NO) position
18. Powered dosage terminals for pH correction
19. Powered dosage terminals for ORP correction
20. 110/115V or 220/240V power configuration
21. Incoming power terminals
22. Fuses
BOTTOM VIEW
23. Female BNC connector for a combination pH electrode
24. 4-mm Banana socket for the pH ground probe
25. Female BNC connector for a combination ORP electrode
26. 4-mm Banana socket for the ORP ground probe

8
Specifications HI 9912
RANGE 0.00 to 14.00 pH and 0 to 1000 mV
RESOLUTION 0.01 pH and 1mV
ACCURACY ±0.02 pH and ±5 mV
(@20°C/68°F)
TYPICAL EMC ±0.1 pH and ±6 mV
DEVIATION
CALIBRATION Through "OFFSET" and "SLOPE" trimmers for pH and
“CAL” for ORP
WEIGHT 1.6 Kg (3.5 lb.)
ENCLOSURE 181 x 221 x 142mm (7.1 x 8.7 x 5.6")
CASE MATERIAL Fiber-reinforced, self-extinguishing ABS
SETPOINT RANGE From 6 to 8 pH and 500 to 900 mV
PROPORTIONAL Two independent controls: pH from 0.0 to 2.0 and
CONTROL ORP from 0 to 200 mV with two separate time cycle
from 0 to 90 seconds
ALARM Relay can be configured as normally open or normally
CONTACT closed (isolated output Max. 2A, Max. 240V, resistive
load, 1,000,000 strokes). The alarm is activated if pH
varies by more than the user-selectable interval (0 to
2 pH), and/or ORP varies by more than the user
selectable interval (0 to 200 mV) from the setpoints or
due to overdosage
POWER SUPPLY 220/240V or 110/115V at 50/60Hz
DOSING
TERMINALS
Two sets of independent terminals (115 to 240V,
Max.2A, 1,000,000 strokes) are activated whenever
pH exceeds the pH setpoint or when ORP falls below
the mV setpoint
ENVIRONMENT -10 to 50°C (14 to 122°F)
max. 95% RH non-condensing

9
CONNECTIONS & WIRINGCONNECTIONS & WIRING
CONNECTIONS & WIRINGCONNECTIONS & WIRING
CONNECTIONS & WIRING
ELECTRODE WITH
BNC CONNECTION
WIRING ACCESS
PORTS
MATCHING PIN FOR GROUND PROBE
GENERAL POINTS
• The relay terminalsrelay terminals
relay terminalsrelay terminals
relay terminals of the controller are poweredpowered
poweredpowered
powered. You can
simply hook up your pumps or electrovalves directly to the
controller and do not need additional power supply.
• Unscrew the 4 screws on the right hand panel and remove the
cover and the gasket. Thread the wires through the access ports
on the right hand side of the controller.
•BeforeBefore
BeforeBefore
Before connecting the controller to the mains, wireconnecting the controller to the mains, wire
connecting the controller to the mains, wireconnecting the controller to the mains, wire
connecting the controller to the mains, wire
the controller completelythe controller completely
the controller completelythe controller completely
the controller completely and make all the connections for
pumps, alarm, electrode, set the alarm threashold and adjust
the settings. Upon completion replace the coverreplace the cover
replace the coverreplace the cover
replace the cover. Only then
connect the controller to the power supply.
ELECTRODE & GROUND PROBE CONNECTIONS
• Simply attach any combination pH and ORP electrode with a
male BNC connector (such as HI 1002/3 and HI 2002/3) to the
female BNC sockets located on the bottom of the casing and twist
them into a secure position.
• HI 9912 also provides for Ground Probes (differ-
ential input) to reduce electrical noise and
interference. The controller is shipped with the
Matching Pin and Reference terminals shorted (see 14 and 15 -
Functional Diagram). If you are not using a matching pin
(ground probe), leave the terminals shortedleave the terminals shorted
leave the terminals shortedleave the terminals shorted
leave the terminals shorted and skip the
next two paragraphs.
• It is recommended that only electrodes that incorporate a match-
ing pin (such as HI 1003/3 and HI 2003/3) are utilized. In this
case simply attach the 4-mm banana connectors of theattach the 4-mm banana connectors of the
attach the 4-mm banana connectors of theattach the 4-mm banana connectors of the
attach the 4-mm banana connectors of the
matchingmatching
matchingmatching
matching pins to the socketspins to the sockets
pins to the socketspins to the sockets
pins to the sockets located next to the BNC
connectors on the outer casing (see 24 and 26 - Functional

10
pH
0
1
2
0
100
200
mV
ALARM
pH
0SECONDS
mV 200 0
TIMER
MINUTES
90
PROPORTIONALSETTINGS
110
2.5 57.5
0SECONDS
pH 2.0 0
TIMER
MINUTES
90
PROPORTIONALSETTINGS
110
2.5 57.5
500 900
CAL
ALARM
ON
OFF
SET
FEED
mV
OFFSET SLOPE
ALARM
ON
OFF
0.5 1.5
pH
HI 9912
mV
ORP
ALARM
8
SET
FEED
ALARM
6
7
ACID
OXID
700
50 150
SET pH
SET ORP
ALARM
LINE
BL DOSING
PUMPS
pH
0
1
2
0
100
200
mV
ALARM
Diagram) and remove the jumpersremove the jumpers
remove the jumpersremove the jumpers
remove the jumpers shorting the matching
pin terminals.
• When using a separate probe for grounding purposes, wire it to
the Matching Pin terminals on the right hand panel and
remove the jumpersremove the jumpers
remove the jumpersremove the jumpers
remove the jumpers (see 14 and 15 - Functional Diagram).
NOTE:
NEVER leave the jumper in when
using an electrode with a match-
ing pin. This can shorten the life
of the electrode (reference) drasti-
cally.
ALARM CONNECTIONS
• The operator can select an alarm threshold of 0.0
to 2.0 pH and 0 to 200 mV by turning the alarm
knob (see 13 and 16 of Functional Diagram). The
alarm can be selected as normally closed ("NC") by
connecting the external device to the C and NC
terminals or normally open ("NO") by connecting
the external device to the C and NO terminals.
RELAY CONNECTIONS
• Wire the external devices (pumps or electrovalves) directly to the
relay terminal strips of the controller (see 18 and 19 - Functional
Diagram). The
terminals areterminals are
terminals areterminals are
terminals are
poweredpowered
poweredpowered
powered and
hence you do notdo not
do notdo not
do not
need an ex-need an ex-
need an ex-need an ex-
need an ex-
ternal powerternal power
ternal powerternal power
ternal power
supplysupply
supplysupply
supply for the
pumps or valves.
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 featureConsent feature
Consent featureConsent feature
Consent feature by which
ORP measurements are adjusted only after pH has been corrected.
The Consent feature makes the pH correctionpH correction
pH correctionpH correction
pH correction the mastermaster
mastermaster
master and the
ORP adjustmentORP adjustment
ORP adjustmentORP adjustment
ORP adjustment the salvesalve
salvesalve
salve for a better control.
REMOVE WHEN
USING MATCHING PIN

11
ALARM DOSING TIME
MINUTES
110
2.5
5
7.5
ALARM
ON
OFF
MAIN POWER SUPPLY CONNECTION
•BeforeBefore
BeforeBefore
Before connecting the unit to the mains, make sureconnecting the unit to the mains, make sure
connecting the unit to the mains, make sureconnecting the unit to the mains, make sure
connecting the unit to the mains, make sure
that the controller is completely wiredthat the controller is completely wired
that the controller is completely wiredthat the controller is completely wired
that the controller is completely wired and that all
connections for pump, alarm, electrode, etc. have been made.
• For 220-240V, short the L1 and N1 termi-
nals. Then wire the external power supply
to the three terminals.
EXTERNAL ELECTRICAL
DEVICE ACTIVATED BY
AN ALARM CONDITION
pH
0
1
2
0
100
200
mV
ALARM
pH
0SECONDS
mV 200 0
TIMER
MINUTES
90
PROPORTIONALSETTINGS
110
2.5 57.5
0SECONDS
pH 2.0 0
TIMER
MINUTES
90
PROPORTIONALSETTINGS
110
2.5 57.5
500 900
CAL
ALARM
ON
OFF
SET
FEED
mV
OFFSET SLOPE
ALARM
ON
OFF
0.5 1.5
pH
HI 9912
mV
ORP
ALARM
8
SET
FEED
ALARM
6
7
ACID
OXID
700
50 150
SET pH
SET ORP
ALARM
LINE
• If the actual measurements are above or below the setpoints by
a margin greater than the user-selectable alarm threshold, the
alarm terminal is activated, triggering the mechanism of your
choice. The alarm LED lights also come on. Due to the ConsentConsent
ConsentConsent
Consent
featurefeature
featurefeature
feature, if the pH is in alarm, both the pH and ORP relays will
be disactivated. However, if only ORP is in an alarm condition,
only the ORP relay will be disactivated.
• The alarm ON/OFF switch is only to disable thedisable the
disable thedisable the
disable the
alarm terminalalarm terminal
alarm terminalalarm terminal
alarm terminal (e.g. the buzzer will not sound).
However, all other functions such as disactivation of
the dosing relays remain unvaried.
• If the pH ON/OFF switch is in the off position, the buzzer/light
will not come on when the pH value is out. The alarm will be
sounded for ORP, unless likewise, the ORP switch is in the off position.
• The controller provides for automatic fail-safeautomatic fail-safe
automatic fail-safeautomatic fail-safe
automatic fail-safe security by
activating the alarm if there is a power failure, regardless of
whether the NC or NO configurations were chosen.
• The alarm is also activated if one or both of
the independent overdosage times are ex-
ceeded. The maximum time that the relay
contacts remain active continuously (overdos-
age timers) can be set from 1 to 10 minutes.
• Once in an alarm condition, the alarm contact remain activated
until the switch is manually put in the off position or the
measurements return to normal values.

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 &NORMAL OPERATION &
NORMAL OPERATION &NORMAL OPERATION &
NORMAL OPERATION &
MEASUREMENTMEASUREMENT
MEASUREMENTMEASUREMENT
MEASUREMENT
8.00
650
pH
mV
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
mV ALARM
OXID
700
pH ALARM
8
SET
FEED
6
7
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 thenOnly then
Only thenOnly 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 featureConsent feature
Consent featureConsent feature
Consent feature by which
ORP measurements are adjusted only after pH has been corrected.
The Consent feature makes the pH correctionpH correction
pH correctionpH correction
pH correction the mastermaster
mastermaster
master and the
ORP adjustmentORP adjustment
ORP adjustmentORP adjustment
ORP adjustment the salvesalve
salvesalve
salve for a better control.

13
pH
OFFSET SLOPE
ALARM
ON
OFF
7.01
4cm
(1½")
HI 7007
4cm
(1½")
HI 7007
4cm
(1½")
HI 7007
Make sure that the pH electrode and any ground probe have been
properly connected and wired to the controller (see preceding pages)
and that the meter is plugged to the mains.
Calibration should be performed at a tem-
perature similar to that of the liquid to be
monitored.
Use a Checktemp (or an accurate thermom-
eter) as reference. Remove the electrode cap if
it is still on the electrode.
During calibration, move the electrode and the
separate ground probe (if in use) together
from one buffer to the next.
If no separate ground probe is being used, make sure that
the Reference and the Matching Pin terminals are shorted
(see 14 - Functional Diagram).
If the electrode (such as HI 1003/3) incorporates a ground probe
(matching pin) then remove the jumper.
OFFSET ADJUSTMENT:
• Rinse the tip of the electrode with pH 7.01 solution (HI 7007),
then dip the bottom 4 cm (1.5”) of the
electrode (and ground probe) in the pH
7.01 buffer.
• Place the Checktemp thermometer in the
buffer solution.
• Wait for the measurement to sta-
bilize and then adjust the
"OFFSET" trimmer (see 6 - Func-
tional Diagram) to display
pH 7.01 on the LCD if the tem-
perature of the buffer solution is
at 25°C (77°F).
• If the temperature of the buffer solution is not 25°C (77°F), refer
to the chart at the end of the manual for the appropriate buffer
value at a given temperature.
pHpH
pHpH
pH CALIBRATIONCALIBRATION
CALIBRATIONCALIBRATION
CALIBRATION

14
4cm
(1½")
HI 7010
pH
OFFSET SLOPE
ALARM
ON
OFF
10.01
SLOPE ADJUSTMENT:
• Rinse the electrode (and ground probe)
thoroughly with water and immerse
the bottom 4 cm (1.5”) in a pH
10.01 (HI 7010) or a pH 4.01 (HI
7004) buffer solution.
• Stir the electrode and wait for the display to stabilize before
adjusting the "SLOPE" trim-
mer (see 5 - Functional
Diagram) to display pH
10.01 (or 4.01) on the LCD
if the temperature of the
buffer solution is at 25°C
(77°F). Otherwise, refer to
the chart at the end of the
manual for the buffer value and adjust the trimmer accordingly.
The pH calibration is now complete.
Make sure that the ORP electrode and any ground probe have been
properly connected and wired to the controller (see preceding pages)
and that the meter is plugged to the mains.
Remove the electrode cap if it is still on the electrode.
During calibration, introduce both the electrode and the separate
ground probe (if in use) to the known solution. If no separate ground
probe is being used, make sure that the Reference
and the Matching Pin terminals are shorted (see
15 - Functional Diagram).
If the electrode (such as HI 2003/3) incorporates a ground probe
(matching pin) then remove the jumper.
• Immerse the electrode in a HI 7020 (or another known) ORP
solution and wait until the reading stabilizes.
• Adjust the CAL trimmer to 230 ±20 mV.
ORP CALIBRATIONORP CALIBRATION
ORP CALIBRATIONORP CALIBRATION
ORP CALIBRATION
4cm
(1½")
HI 7020
CAL
ALARM
ON
OFF
mV
ORP 230

15
Make sure that the electrode (and any ground probe) is properly
installed and calibrated (see the preceding pages).
FOR pH
Simply turn the pH ACID FEED dial (see 3 - Func-
tional Diagram) and choose the desired value between
6 and 8 pH.
DOSING DIRECTION
The dosing terminals are activated when the pH value exceeds the
setpoint. HI 9912 will then dose acidic solutions until the user-selected
setpoint is reached.
ADJUSTEMENT OF SETPOINT(S)ADJUSTEMENT OF SETPOINT(S)
ADJUSTEMENT OF SETPOINT(S)ADJUSTEMENT OF SETPOINT(S)
ADJUSTEMENT OF SETPOINT(S)
FOR ORP
Simply turn the ORP OXID FEED dial (see 11 -
Functional Diagram) and choose the desired value
between 500 and 900 mV
DOSING DIRECTION
The dosing terminals are activated when the ORP falls below the
setpoint. HI 9912 will dose oxidants until the user-selected setpoint is
reached.
pH
ALARM
8
SET
FEED
6
7
ACID
500 900
SET
FEED
mV
ALARM
OXID
700
0SECONDS
pH 2.0 090
PROPORTIONAL SETTINGS
0.5 1.5
0SECONDS
mV 200 090
PROPORTIONAL SETTINGS
50 150
PROPORTIONAL CONTROLPROPORTIONAL CONTROL
PROPORTIONAL CONTROLPROPORTIONAL CONTROL
PROPORTIONAL CONTROL
In order to optimize the controlling process and reduce the amount of
chemicals used, it is recommended to use a proportional dosage
appropriate for the system.
HI 9912 allows for a proportional
band of 0 to 2.0 pH and 0 to
200 mV (delta) as well as two
independent time cycles from 0 to
90 seconds. The proportional dos-
age is obtained by personalizing a
current pulse whose height equals
the pH or ORP proportional delta
and the length corresponds to the
selected time cycle.
The controller will enter proportional dosage at setpointproportional dosage at setpoint
proportional dosage at setpointproportional dosage at setpoint
proportional dosage at setpoint
minusminus
minusminus
minus (in case of ORP) or plusor plus
or plusor plus
or plus (for pH) the preselected deltathe preselected delta
the preselected deltathe preselected delta
the preselected delta.
It will then keep the dosing relays activated for a period proportional

16
0SECONDS
pH 2.0 090
PROPORTIONAL SETTINGS
0.5 1.5
DpH
Seconds15 30 45 60
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
15 30 45 60
DpH
Seconds15 30 45 60
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
15 30 45 60
DpH
Seconds15 30 45 60
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
15 30 45 60
e.g. pH proportional control
Setpoint = 7.4 pH
Measured value = 8.90 pH
Delta = 8.90 - 7.40 = 1.50 pH
Proportional settings = pH set to 2 and time cycle to 60 seconds
The controller will be dosing
acids to reduce pH to the
desired limit. Since it is 1.50/
2.00 = 75% away from the
ideal setting, it will keep the
dosing relay activated for 75%
of the time over the predeter-
mined 60 seconds. The
terminals are hence theoreti-
cally activated for 45 seconds
and off for 15 seconds.
In order to avoid over dosage
of fast responding samples or
highly concentrated chemicals
or under dosage with slow
reacting or weak chemicals,
the controller provides even a
more accurate control.
As the graphs show, it does
that by stopping the dosage
as soon as the current pulse
curve intersects the dosage
curve. This means shortening
the dosage period if the chemi-
cals have reacted quickly or lengthening it if the measured pH
continues to drift from the ideal setpoint as can be seen from the
graphs.
to the difference between the measurement less the setpoint over the
cycle.
NOTE:
• If the setting is left at 0 pH or 0 mV, the controller will operate
as an ON/OFF control with no proportional dosage. In this case
the controller will operate with a 0.1 pH or 7 mV hysteresis.
•Do not set the time cycle to 0Do not set the time cycle to 0
Do not set the time cycle to 0Do not set the time cycle to 0
Do not set the time cycle to 0. This causes the relay to chatter
and can be detrimental to the controlling system and pump.

17
ALARM DOSING TIME
MINUTES
110
2.5
5
7.5
e.g. ORP proportional control
Setpoint = 750 mV
Measured value = 725 mV
Delta = 750 - 725 = 25 mV
Proportional settings = mV set to 100 and time cycle to 60 seconds
The controller will be dosing
oxidants to increase redox to
the desired value. Since it is
25/100 = 25% away from
the ideal setting, it will keep
the dosing contacts activated
for 25% of the time over the
predetermined 60 seconds.
The terminals are hence acti-
vated for 15 seconds and off
for 45 seconds until the next
cycle.
0SECONDS
mV 200 090
PROPORTIONAL SETTINGS
50 150
OVERDOSAGE TIMERSOVERDOSAGE TIMERS
OVERDOSAGE TIMERSOVERDOSAGE TIMERS
OVERDOSAGE TIMERS
HI 9912 provides for two independent overdosage timers. The
operator can set the maximum amount of time that the dosage
terminals should continuously remain acti-
vated from 1 to 10 minutes . Should this
period elapse, the alarm terminals are acti-
vated (and dosage disactivated to ensure
that chemicals have not run out or pumps
or electrovalves have not ceased to function
properly).
DmV
Seconds15 30 45 60
25
50
75
100
15 30 45 60

18
Please refer to the following chart for a more accurate pH calibra-
tion:
For instance, if the buffer temperature is 25°C (77°F), calibrate the
meter to read 4.01, 7.01 or 10.01 on the display.
If the buffer temperature is 20°C, calibrate it to 4.00, 7.03 or
10.06.
If the buffer temperature is 50°C, calibrate it to 4.06, 6.98 or 9.82.
pHpH
pHpH
pH VALUES AT VARIOUSVALUES AT VARIOUS
VALUES AT VARIOUSVALUES AT VARIOUS
VALUES AT VARIOUS
TEMPERATURESTEMPERATURES
TEMPERATURESTEMPERATURES
TEMPERATURES
TEMP pHVALUES
°C °F 4.01 6.86 7.01 9.18 10.01
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
32
41
50
59
68
77
86
95
104
113
122
131
140
149
158
4.01
4.00
4.00
4.00
4.00
4.01
4.02
4.03
4.04
4.05
4.06
4.07
4.09
4.11
4.12
6.98
6.95
6.92
6.90
6.88
6.86
6.85
6.84
6.84
6.83
6.83
6.84
6.84
6.85
6.85
7.13
7.10
7.07
7.04
7.03
7.01
7.00
6.99
6.98
6.98
6.98
6.98
6.98
6.99
6.99
9.46
9.39
9.33
9.27
9.22
9.18
9.14
9.10
9.07
9.04
9.01
8.99
8.97
8.95
8.93
10.32
10.24
10.18
10.12
10.06
10.01
9.96
9.92
9.88
9.85
9.82
9.79
9.77
9.76
9.75

19
REDOX MEASUREMENTREDOX MEASUREMENT
REDOX MEASUREMENTREDOX MEASUREMENT
REDOX MEASUREMENT
Redox measurements allow the quantification of the oxidizing or
reducing power of a solution, and are commonly expressed in mV.
Oxidation may be defined as the process during which a molecule (or
an ion) loses electrons and reduction as the process by which electrons
are gained.
Oxidation is always coupled together with reduction so that as one
element gets oxidized, the other is automatically reduced, therefore
the term oxidation-reduction is frequently used.
Redox potentials are measured by an electrode capable of absorbing
or releasing electrons without causing a chemical reaction with the
elements with which it comes into contact.
The electrodes most usually available for this purpose have a plati-
num surface. When a platinum electrode is immersed in an oxidizing
solution a monomolecular layer of oxygen is developed on its surface.
This layer does not prevent the electrode from functioning, but it
increases the response time. The opposite effect is obtained when the
platinum surface absorbs hydrogen in the presence of reducing
mediums. This phenomenon is rough on the electrode.
To make accurate redox measurements the surface of the electrode
must be clean and smooth. At certain mV and pH values, especially
those found in pools, the ORP electrode requires a considerable
amount of time before it reads the proper value. This is due to the
fact that it is moving from a reducing to an oxidizing state. Once it
reaches a stable condition though, it reacts rapidly to changes.
Hence when the process is first set up allow sufficient time for the ORP
electrode to adapt itself to the sample stream.
As with pH electrodes, gel-filled redox electrodes are more suitable for
industrial applications due to less maintenance requirements.
In order to test that the ORP electrode is functioning properly,
immerse it into a HI 7020 solution. The measured value should be
between 200 and 250 mV.
When not in use, the electrode tip should be kept moist in order for
the reference junction, especially Teflon models, to respond quickly.
Otherwise, soak the electrode overnight in a HI 70300 storage
solution or allow more time upon installation for its stabilization. Also
keep the electrode far from any type of mechanical stress which might
cause damage.
Install the electrode in such a way that it is constantly in a well filled
with the sample (stream or tank) and does not dry up.

20
The protective cap should also be filled with a few drops of HI 70300
storage solution if the electrode is not being used at all.
Note: With industrial applications, it is always good practice to keep
at least one spare electrode handy. When anomalies are not
resolved with a simple maintenance, change the electrode to
see if the problem is alleviated.
ELECTRODE CONDITIONINGELECTRODE CONDITIONING
ELECTRODE CONDITIONINGELECTRODE CONDITIONING
ELECTRODE CONDITIONING
& MAINTENANCE& MAINTENANCE
& MAINTENANCE& MAINTENANCE
& MAINTENANCE
PREPARATION
Remove the protective cap.
DO NOT BE ALARMED IF ANY SALT DEPOSITS ARE PRESENT.
This is normal with electrodes and they will disappear when rinsed
with water.
During transport tiny bubbles of air may have formed inside the glass
bulb (membrane). Shake down the electrode as you would do with a
glass thermometer to remove these bubbles.
If the bulb and/or junction are dry, soak the electrode in a HI 70300
Storage Solution overnight.
STORAGE
To minimize clogging and assure a quick response time, the glass
bulb and the junction should be kept moist and not allowed to dry
out. This can be achieved by installing the electrode in such a way
that it is constantly in a well filled with the sample (stream or tank).
When not in use, pour a few drops of HI 70300 Storage Solution or,
in its absence, HI 7007 pH 7.01 Buffer Solution in the protective cap
and replace it on the electrode.
Note: NEVER STORE THE ELECTRODE IN DISTILLED OR DEIONIZED
WATER.
PERIODIC MAINTENANCE
Inspect the electrode and the cable. The cable used for the connection
to the controller must be intact and there must be no points of broken
insulation on the cable or cracks on the electrode stem or bulb.
The connector must be clean and dry. If any scratches or cracks are
present, replace the electrode. Rinse off any salt deposits with water.
CLEANING PROCEDURE
Soak in Hanna HI7061 General Cleaning Solution for ½ hour.