Hanna Instruments HI 9931 User manual

Instruction Manual
http://www.hannainst.com TheseInstrumentsarein
Compliancewith theCE Directives
ALARM
LINE
SET EC
0SECONDS
mS1.6 0
TIMER
MINUTES
90
45
FINESLOPE
CAL
COARSE
PROPORTIONALSETTINGS
ALARMAUTO
MANUAL
SET
READ
FERT.
SETPOINT
HI 9
1
2.5
5
0.8
mS
EC
FEED
EC
0
1
2
ALARM
mAOUTPUT
4/200/20
mS
ZERO
CAL
HI 9931 - HI 9934
Wall Mounted
Conductivity & TDS
Controllers

2
DearCustomer,
Thank you for choosing a Hanna Product.
Please read this instruction manual carefully before using the instru-
ment.This manual will provide youwith 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
EN50081-1,50082-1and61010-1.
ISO 9000 Certified
Company since 1992
PRELIMINARY EXAMINATION........................................................3
GENERAL DESCRIPTION ................................................................3
MECHANICAL LAYOUTS.................................................................4
FUNCTIONAL DIAGRAM HI 9931..................................................6
FUNCTIONAL DIAGRAM HI 9934..................................................9
CONNECTIONS & WIRING ..........................................................12
NORMAL OPERATION & MEASUREMENT .....................................15
CALIBRATION.............................................................................16
ADJUSTEMENT OF SETPOINT......................................................17
PROPORTIONAL CONTROL.......................................................... 18
OVERDOSAGETIMER ..................................................................20
PROBE CLEANING & MAINTENANCE ............................................20
SUGGESTED INSTALLATIONS FOR EC/TDS PROBES.......................21
ACCESSORIES.............................................................................23
WARRANTY ................................................................................25
OTHER PRODUCTS FROM HANNA...............................................26
CE DECLARATION OF CONFORMITY.............................................. 27
TABLE OF CONTENTSTABLE OF CONTENTS
TABLE OF CONTENTSTABLE OF CONTENTS
TABLE OF CONTENTS

3
PRELIMINARY EXAMINATIONPRELIMINARY EXAMINATION
PRELIMINARY EXAMINATIONPRELIMINARY EXAMINATION
PRELIMINARY EXAMINATION
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.
GENERAL DESCRIPTIONGENERAL DESCRIPTION
GENERAL DESCRIPTIONGENERAL DESCRIPTION
GENERAL DESCRIPTION
Hanna's wall-mounted conductivity and TDS controllers with
proportional control are designed to meet a variety of process control
requirements, especially those in horticultural, hydroponics and
agricultral applications.
The controllers operate with the optional Hanna 4-ring probes to
provide a linear and repeatble measurement. The conductivity/TDS
probes can be installed quickly and easily. Simply plug the DIN
connector into the socket and tighten the retainer ring.
The probes incorporate a tempertaure sensor and the contoller will
automatically compensate for the temperature effect. Accurate mea-
surements are displayed on a large LCD.
The controllers come equipped with relays operating at a maximum of
2A (240V).
The 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
electricaldevice.

4
MECHANICAL LAYOUTSMECHANICAL LAYOUTS
MECHANICAL LAYOUTSMECHANICAL LAYOUTS
MECHANICAL LAYOUTS
DIN connector
WIRING ACCESS
PORTS
EC
0
1
2
ALARM
mA OUTPUT
4/20 0/20
mS
0SECONDS
mS 1.6 0
TIMER
MINUTES
90
45
FINE
COARSE
PROPORTIONAL SETTINGS
ALARM AUTO
MANUAL
SET
READ
FERT.
SET POINT
HI 9931
110
2.5
5
7.5
0.8
mS
EC
FEED
ALARM
LINE
SET EC
LCD DISPLAY
CALIBRATION
TRIMMERS
CONTROL KNOBS
AND SWICHES
OUTPUT CONTACTS
DOSING TERMINALS
POWER SUPPLY
TERMINALS
ALARM CONTACTS
RECORDER OUTPUT
SWITCH
SLOPE
CAL
ZERO
CAL
Fig. 2
Fig. 1
Figure 1 illustrates the connector for probe and the wiring access
ports.
Figure 2 illustrates the controls and terminals.
The recorder output terminals are isolated from the controller circuitry
to avoid any interference and are user-switchable between 0 to 20
mA or 4 to 20 mA.
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 at 50/
60 Hz power supplies.

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
FRONTPANEL
FUNCTIONAL DIAGRAM HI 9931FUNCTIONAL DIAGRAM HI 9931
FUNCTIONAL DIAGRAM HI 9931FUNCTIONAL DIAGRAM HI 9931
FUNCTIONAL DIAGRAM HI 9931
EC
0
1
2
ALARM
mA OUTPUT
4/20 0/20
mS
0SECONDS
mS 1.6 0
TIMER
MINUTES
90
45
FINE SLOPE
CAL
COARSE
PROPORTIONAL SETTINGS
ALARM AUTO
MANUAL
SET
READ
FERT.
SET POINT
HI 9931
110
2.5
5
7.5
0.8
mS
EC
FEED
ALARM
LINE
SET EC
ZERO
CAL
1
2
3
4
5
6
7
8
9
10
11 12
13
14
15
16
17
18
19
20
Left panel
1. Liquid Crystal Display
2. Slope calibration trimmer
3. Fine setpoint trimmer
4. Coarse setpoint trimmer
5. Zero calibration trimmer
6. Alarm LED warning signal
7. Alarm disable switch
8. READ for actual measurement and SET for setpoint
adjustment
9. Dosing LEDsignal
10. Proportional conductivity band setting
11. Proportional time cycle setting
12. Overdosage timer
Right panel
13. Conductivity alarm setting from 0 to 2.0 mS/cm (EC)
14. Recorder output contacts
15. 0 to 20 or 4 to 20 mA output selector
16. Triple contact alarm in a Normally Closed (NC) or a Normally
Open (NO) position.

7
Unplug the instrument from the power supply before
wiring or replacing the fuses.
21
17. Powered dosage terminals (Relay)
18. 110/115V or 220/240V power configuration
19. Incoming power terminals
20. Fuses
BOTTOM VIEW
21. Female DIN connector for conductivity probe

8
SETPOINTRANGE From 0to 10.00 mS/cm
Specifications HI9931
RANGE 0.00 to 10.00 mS/cm (EC)
RESOLUTION 0.01mS/cm
ACCURACY ±2%F. S.
(@20C/68 F)
TYPICALEMC ±2% F.S.
DEVIATION
PROPORTIONAL Conductivity from 0.0 to 1.6 mS/cm and
CONTROL time cycle from 0 to 90 seconds
ALARM
CONTACTS
DOSINGTERMINALS
PROBE (optional) 4-ring potentiometric with built-in temperature sensor
POWER SUPPLY 220/240Vor110/115V at50/60Hz
ENVIRONMENT -10 to 50°C (14 to 122°F)
max. 95% RH non-condensing
WEIGHT 1.6Kg (3.5 lb.)
ENCLOSURE 181x 221 x 142mm (7.1 x 8.7 x5.6")
CASE MATERIAL Fiber-reinforced, self-extinguishing ABS
Terminal can be configured as normally open or
normally closed (isolated output Max. 2A, Max. 240V,
resistive load, 1,000,000 strokes). The alarm is
activated if conductivity exceeds by more than the user-
selectable interval (0 to 2.0 mS/cm) from the setpoint
or due to overdosage
Relay (115 to 240V, Max.2A,1,000,000 strokes) is
activated whenever conductivity falls below the setpoint
CALIBRATION Through"ZERO CAL" and"SLOPE CAL" trimmers

9
FUNCTIONAL DIAGRAM HI 9934FUNCTIONAL DIAGRAM HI 9934
FUNCTIONAL DIAGRAM HI 9934FUNCTIONAL DIAGRAM HI 9934
FUNCTIONAL DIAGRAM HI 9934
TDS
0
200
400
ALARM
mA OUTPUT
4/20 0/20
ppm
TIMER
MINUTES
FINE SLOPE
CAL
COARSE
PROPORTIONAL SETTINGS
AUTO
MANUAL
SET
READ
FERT.
SET POINT
110
2.5
5
7.5
FEED
ALARM
LINE
SET TDS
ZERO
CAL
1
2
3
4
5
6
7
8
9
10
11 12
13
14
15
16
17
18
19
20
0SECONDS
ppm 400 090
45
HI 9934
200
ppm
TDS
ALARM
FRONTPANEL
Left panel
1. Liquid Crystal Display
2. Slope calibration trimmer
3. Fine setpoint trimmer
4. Coarse setpoint trimmer
5. Zero calibration trimmer
6. Alarm LED warning signal
7. Alarm disable switch
8. READ for actual measurement and SET for setpoint
adjustment
9. Dosing LEDsignal
10. Proportional TDS band setting
11. Proportional time cycle setting
12. Overdosage timer
Right panel
13. TDS alarm setting from 0 to 400 ppm (mg/L)
14. Recorder output contacts
15. 0 to 20 or 4 to 20 mA output selector
16. Triple contact alarm in a Normally Closed (NC) or a Normally

10
21
Open (NO) position.
17. Powered dosage terminals (Relay)
18. 110/115V or 220/240V power configuration
19. Incoming power terminals
20. Fuses
BOTTOM VIEW
21. Female DIN connector for TDS probe

11
Specifications HI9934
RANGE 0.00to 1999 ppm(mg/L)
RESOLUTION 1 ppm (mg/L)
ACCURACY ±2%F. S.
(@20C/68 F)
TYPICALEMC ±2% F.S.
DEVIATION
PROPORTIONAL TDSfrom0to400ppm and
CONTROL time cycle from 0 to 90 seconds
ALARM
CONTACTS
DOSINGTERMINALS
TDSRATIO 0.65 ppm (mg/L) = 1 µS/cm
POWER SUPPLY 220/240Vor110/115V at50/60Hz
ENVIRONMENT -10 to 50°C (14 to 122°F)
max. 95% RH non-condensing
WEIGHT 1.6Kg (3.5 lb.)
ENCLOSURE 181x 221 x 142mm (7.1 x 8.7 x5.6")
CASE MATERIAL Fiber-reinforced, self-extinguishing ABS
Terminals can be configured as normally open or
normally closed (isolated output Max. 2A, Max. 240V,
resistive load, 1,000,000 strokes). The alarm is
activated if TDS exceeds by more than the user-
selectable interval (0 to 400 ppm) from the setpoint
or due to overdosage.
Relay (115 to 240V, Max.2A, 1,000,000 strokes) are
activated whenever TDS falls below the setpoint
PROBE(optional) 4-ring potentiometric with built-in temperature sensor
CALIBRATION Through "ZERO CAL" and "SLOPE CAL" trimmers
SETPOINTRANGE From 0 to 1999 ppm (mg/L)

12
GENERAL POINTS
• The relay terminalsrelay terminals
relay terminalsrelay terminals
relay terminals of the controller are poweredpowered
poweredpowered
powered. This
means that you can simply hook up your pump or electrovalve
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, probe, set the alarm threshold 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.
PROBE CONNECTION
• Attach the conductivity/TDS probe (HI 3002, HI 3001D or
HI 7638) to the DIN socket located on the bottom of the casing.
Align the guide on the connector with the socket, push the
connector in and tighten the retainer ring. (HI 3002 is more
suitable for direct immersion in the tank, vat or pipes. HI 3001D
can be mounted directly into a pipe and HI 7638 is recom-
mended for high temperature and pressure applications).
• The probes incorporate a temperature sensor and the controller’s
circuitry automatically compensates for the temperature effect.
RELAY CONNECTIONS
• Wire the external devices (pumps or electrovalves) directly to the
relay terminal strips of the controller (see 17 - Functional Dia-
CONNECTIONS & WIRINGCONNECTIONS & WIRING
CONNECTIONS & WIRINGCONNECTIONS & WIRING
CONNECTIONS & WIRING
DIN connector
WIRING ACCESS
PORTS

13
SET EC
ALARM
LINE
BL DOSING PUMP
0SECONDS
mS 1.6 0
TIMER
MINUTES
90
45
FINE
COARSE
PROPORTIONAL SETTINGS
ALARM AUTO
MANUAL
SET
READ
FERT.
SET POINT
HI 9931
110
2.5
5
7.5
0.8
mS
EC
FEED
SLOPE
CAL
ZERO
CAL
EC
0
1
2
ALARM
mA OUTPUT
4/20 0/20
mS
gram). The terminals are poweredterminals are powered
terminals are poweredterminals are powered
terminals are powered and hence you do notdo not
do notdo not
do not
need an external power supplyneed an external power supply
need an external power supplyneed an external power supply
need an external power supply for the pumps or valves.
ALARM CONNECTIONS
• Theoperatorcanselectanalarmthresh-
old of 0.0 to 2.0 mS/cm for HI 9931
and 0 to 400 ppm for HI 9934 by
turning the alarm knob (see 13 -
FunctionalDiagram).Iftheactualmea-
surements are above the setpoint by a
margin greater than the user-select-
ablealarmthreshold,thealarmterminalisactivated.
Thealarmcanbe selectedasnormallyclosed("NC")byconnecting
the external device to the C and NC terminals or normally open
("NO") by connecting the external device to the C and NO
terminals.
• When activated, the alarm contacts will open or close, triggering
the mechanism of your choice. When the alarm is activatedalarm is activated
alarm is activatedalarm is activated
alarm is activated
all other terminalsall other terminals
all other terminalsall other terminals
all other terminals (such as dosing relay etc.) areare
areare
are
disactivateddisactivated
disactivateddisactivated
disactivated. The alarm LED light also comes on.
• The alarm AUTO/MANUAL switch (see 7 - Functional Diagram) is
only to disable the alarm terminaldisable the alarm terminal
disable the alarm terminaldisable the alarm terminal
disable the alarm terminal (e.g. the
buzzer will not sound). However, all other functions
such as disactivation of the dosing relay remain
unvaried, i.e. the pump ceases to dose until the
alarm condition is alleviated.
EC
0
1
2
ALARM
mA OUTPUT
4/20 0/20
mS
TDS
0
200
400
ALARM
mA OUTPUT
4/20 0/20
ppm
SET EC
ALARM
LINE
0SECONDS
mS 1.6 0
TIMER
MINUTES
90
45
FINE
COARSE
PROPORTIONAL SETTINGS
ALARM AUTO
MANUAL
SET
READ
FERT.
SET POINT
HI 9931
110
2.5
5
7.5
0.8
mS
EC
FEED
SLOPE
CAL
ZERO
CAL
EC
0
1
2
ALARM
mA OUTPUT
4/20 0/20
mS
EXTERNAL ELECTRICAL
DEVICE ACTIVATED BY
AN ALARM CONDITION
ALARM
AUTO
MANUAL

14
• The contoller provides for automatic fail-safe secruityautomatic fail-safe secruity
automatic fail-safe secruityautomatic fail-safe secruity
automatic fail-safe secruity 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 the overdosage time is exceeded.
The maximum time that the relay contacts
remain active continuously can be set from 1
to 10 minutes.
• Once in an alarm condition, the alarm contact
remains activated until the switch is put in the
manual position or the measurements return to normal values.
TIMER
MINUTES
110
2.5
5
7.5
RECORDER OUTPUT CONNECTIONS
• The recorder output contacts are iso-
lated from the controller circuitry to avoid
interference. Select 0 to 20 mA or 4 to 20
mA with the switch (see 15 - Functional
Diagram) before wiring the recorder to the terminals. The output
mA value is proportional and is the measured conductivity or TDS
over the entire range. For example, when HI 9931 measures
2.00 mS/cm (EC), the output values are 4 mA or 7.2 mA based
on whether the 0-20 or 4-20 output was respectively selected.
Likewise, when HI 9934 measures 1500 ppm (mg/L), the output
values are 15 mA or 16 mA based on whether the 0-20 or 4-20
output was selected.
Output mA
selector
0/204/20
RECORDER
SET EC
ALARM
LINE
0SECONDS
mS 1.6 0
TIMER
MINUTES
90
45
FINE
COARSE
PROPORTIONAL SETTINGS
ALARM AUTO
MANUAL
SET
READ
FERT.
SET POINT
HI 9931
110
2.5
5
7.5
0.8
mS
EC
FEED
SLOPE
CAL
ZERO
CAL
EC
0
1
2
ALARM
mA OUTPUT
4/20 0/20
mS
TEMPERATURE COMPENSATION
Temperature affects conductivity and TDS mesurements considerably
(approx. 2% per °C). You however do not need to worry about
having to compensate for this or go through complicated calculations
since all three probes recommended in this manual (HI 7638,
HI 3002 and HI 3001D) compensate for temperature automatically.

15
MAIN POWER SUPPLY CONNECTION
•BeforeBefore
BeforeBefore
Before connecting the unit to the mainsconnecting the unit to the mains
connecting the unit to the mainsconnecting the unit to the mains
connecting the unit to the mains, make sure
that the controller is completely wiredcontroller is completely wired
controller is completely wiredcontroller is completely wired
controller is completely wired and that all
connections for pump, alarm, probe, etc. have been made.
• For 220-240V, short the L1 and N1 termi-
nals. Then wire the external power supply
to the three terminals as shown.
• For 110-115V, short the L and L1 termi-
nals and the N1 and Neutral. 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 connect the controller to the mains.
Neutral
Line
POWER
SUPPLY
220 VAC
Configuration
L
L1
N1
Neutral
Line
POWER
SUPPLY
L
L1
N1
110 VAC
Configuration
110 VAC
Configuration
Make sure that the controller has been properly calibrated before
commencing and that the conductivity/TDS setpoint has been ad-
justed (see following pages).
The conductivity/TDS probe must be properly connected and wired to
the controller (see preceding pages).
Theprotectivesleevemustnot be removedandtheholesonthesleeve
should be near the top (the cable end). The probe must be immersed
in the solution above the air-vent holes on the external sleeve. The
probe must be installed in such a way as to minimize presence of air
bubbles (see probe installation tips at the end of the
manual).
Ensure that the selector (see 8 - Functional Diagram) is in
the“READ” mode.
Thecontrollerprovidesforavisualdosingstatusthrough
the “FERT FEED” LED (see 9 - Functional Diagram).
The actual conductivity (EC) or TDS value will be dis-
played on the LCD in mS/cm or ppm, respectively.
NORMAL OPERATIONNORMAL OPERATION
NORMAL OPERATIONNORMAL OPERATION
NORMAL OPERATION
& MEASUREMENT& MEASUREMENT
& MEASUREMENT& MEASUREMENT
& MEASUREMENT
FERT.
FEED
SET
READ
ppm
TDS
mS
EC
12401.20

16
Make sure that the probe has been properly connected and
wired to the controller (see preceding pages) and that the
meter is plugged to the mains.
Calibration should be ideally performed at a temperature
similar to that of the liquid to be monitored.
Ensure that the controller is in the “READ” position.
ZERO ADJUSTMENT:
• Leave the probe in the air and
make sure that it is dry.
• The LCD should show 0. If neces-
saryadjustthe"ZEROCAL"trimmer
to display zero.
SLOPE ADJUSTMENT:
• Pour sufficient amount of a known conductivity or TDS solution in
a beaker. The solution should be close to the sample stream to be
monitored. For example, when using the HI 9931, choose
HI 7031L with a 1.41 mS/cm value at 25 °C if the measure-
ments are in the 1.2 to 2.5 EC range. Similarly, utilize
HI 70442L with a value of 1500 ppm at 25 °C if controlling your
procress with HI 9934.
• Immersetheprobe inthebeakeresuring
that the holes on the sleeve of the
probe are completely covered.
• Stir the probe and gently tap it on the
bottom of the beaker to ensure that
any air bubbles trapped inside the
sleeve escape. Best results are obtained
when the probe is not too close to the walls of the beaker nor
lying on the bottom.
• Wait for the reading to stabilize.
Adjust the "SLOPE CAL" trimmer to
display the same value as the cali-
bration solution at 25 °C. For
example, with HI 7031L, you should adjust the dispaly to 1.41
mS/cm and with HI 70442 to 1500 ppm.
CALIBRATIONCALIBRATION
CALIBRATIONCALIBRATION
CALIBRATION
SET
READ
FINE
COARSE
SET POINT
SLOPE
CAL
ZERO
CAL
0
Min7cm
(2.8“)
FINE
COARSE
SET POINT
mS
EC
SLOPE
CAL
ZERO
CAL
1.41

17
• Once the controller is calibrated to a solution by referring to its
value at 25 °C, all subsequent measurements are temperature
compensated to 25 °C. You can also obtain temperature compen-
sation to a different temperature reference point by calibrating
the meter to that value. For example, the conductivity and TDS
value of HI 7031L and HI 70442L at 20 °C are 1.28 mS/cm
and 1358 ppm, respectively. By adjusting the display to these
two values, all subsequent measurements are compensated to a
base temperature of 20 °C.
Calibration is now complete.
Make sure that the probe is properly installed and calibrated (see
the preceding pages).
Turn the switch to the "SET" position (see 8 - Functional Diagram).
The display will show the previously adjusted (e.g. 1.60 mS/cm or
1400 ppm).
Using a small screwdriver, first adjust the setpoint through the
COARSE trimmer and then fine tune it to your required level with the
FINE trimmer (see 4 and 3 - Functional Diagram) until the desired
value is displayed (e.g. 2.1 mS/cm or 1700 ppm).
ADJUSTEMENT OF SETPOINTADJUSTEMENT OF SETPOINT
ADJUSTEMENT OF SETPOINTADJUSTEMENT OF SETPOINT
ADJUSTEMENT OF SETPOINT
SET
READ
mS
EC 1.60
FINE
COARSE
SET POINT
mS
EC
SLOPE
CAL
ZERO
CAL
1.60
FINE
COARSE
SET POINT
mS
EC
SLOPE
CAL
ZERO
CAL
2.10

18
PROPORTIONAL CONTROLPROPORTIONAL CONTROL
PROPORTIONAL CONTROLPROPORTIONAL CONTROL
PROPORTIONAL CONTROL
In order to optimize the controlling process and reduce the amount of
chemicalsandfertilizersused,it is recommendedtouseaproportional
dosage appropriate for the system.
HI 9931 and HI 9934 allow for a proportional band (delta) of 0 to
1.6 mS/cm and 0 to 400 ppm for conductivity (EC) and TDS,
respectively.Eachcontrolleralso providesforatimecycle from0to90
seconds. The proportional dosage is obtained by personalizing a
curent pulse whose height equals the EC or TDS proportional delta
and the length corresponds to the selected time cycle.
The controller will enter proportional dosage at the setpoint minus the
preselected delta. It will then keep the dosing relay activated for a
period proportional to the difference between the actual measurement
less the setpoint over the cycle.
If the setting is left at 0 mS/cm or 0 ppm, the controller will operate
as an ON/OFF control with no proportional dosage. The hysteresis of
such an ON/OFF control will be 0.1 mS/cm or 15 ppm, respectively.
0SECONDS
mS 1.6 090
45
PROPORTIONAL SETTINGS
0.8
PROPORTIONAL SETTINGS
0SECONDS
ppm 400 090
45200
e.g. HI 9931 proportional control
Setpoint = 2.2 mS/cm (EC)
Measured value = 1.6 mS/cm
Delta = 2.2 - 1.6 = 0.6 mS/cm
Proportional settings = EC set to 0.8 and time cycle to 60 seconds
Thecontrollerwillbedosing fertilizerstoincreasetheECto the desired
limit. Since it is 0.6/0.8 = 75%
away from the ideal setting, it will
keep the dosing relay activated for
75% of the time over the preselected
60 seconds. The terminals are hence
theoretically activated for 45 seconds
0SECONDS
mS 1.6 090
45
PROPORTIONAL SETTINGS
0.8
DmS
Seconds15 30 45 60
0.20
0.40
0.60
0.80
15 30 45 60

19
e.g. HI 9934 proportional control
Setpoint = 1600 ppm TDS)
Measured value = 1550 ppm
Delta = 1600 - 1550 = 50 ppm
Proportionalsettings = ppm set to 200 and timecycle to 60 seconds
The controller will be dosing fertilizers to reach the desired value.
Sinceitis50/200= 25%awayfromthe
ideal setting, it will keep the dosing relay
activated for 25% of the time over the 60
second period. The terminals are hence
activated for 15 seconds and off for 45
seconds until the next cycle.
and off for 15 seconds.
In order to avoid over dosage of highly
concentrated chemicals or fertilizers, the
controller provides even a more accurate
control.
As the graphs show, it does that by
stopping the dosage as soon as the cur-
rentpulsecurveintersectsthedosagecurve.
This means shortening the dosage period
if the chemicals have reacted quickly or
lengthening it if the measured conductiv-
itycontinuestodriftfromtheidealsetpoint
as can be seen from the graphs.
DmS
Seconds15 30 45 60
0.20
0.40
0.60
0.80
15 30 45 60
PROPORTIONAL SETTINGS
0SECONDS
ppm 400 090
45200
DmS
Seconds15 30 45 60
0.20
0.40
0.60
0.80
15 30 45 60
Dppm
Seconds15 30 45 60
50
100
150
200
15 30 45 60

20
OVERDOSAGE TIMEROVERDOSAGE TIMER
OVERDOSAGE TIMEROVERDOSAGE TIMER
OVERDOSAGE TIMER
HI 9931 and HI 9934 provide for an overdosage alarm system. The
operator can set the maximum amount of time that the dosage
terminals should continuously remain activated from 1 to 10 minutes
. Should this period elapse, the alarm
terminals are activated (and dosage
disactivatedtoensurethatfertilizersorchemi-
cals have not run out or pumps or
electrovalves have not ceased to function
properly).
TIMER
MINUTES
110
2.5
5
7.5
PREPARATION
Make sure that the protective sleeve is on the probe shaft and that
the air-vent holes are on the top (nearer to the cable).
STORAGE
The conductivity/TDS probes should be stored dry. If the probes are
not to be used for a while, clean and dry them throroughly (see
below) before storing them in a dry store room.
PERIODIC MAINTENANCE
Inspect the probe 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 probe sleeve.
Connector must be clean and dry. If any cracks are present, replace
the probe and cable.
CLEANING PROCEDURE
Remove the sleeve and soak the probe in a Hanna HI7061 General
Cleaning Solution for 1 hour. Wash the sleeve with plenty of water
and remove any dirt.
If the probe has been left in highly concentrated fertilizer solution and
does not seem to become clean, repeat the cleaning procedure.
The rings can also be cleaned with a cloth. Make sure that the cloth
is made of a soft and non-abrasive material and does not scratch the
rings.
PROBE CLEANINGPROBE CLEANING
PROBE CLEANINGPROBE CLEANING
PROBE CLEANING
& MAINTENANCE& MAINTENANCE
& MAINTENANCE& MAINTENANCE
& MAINTENANCE