Hanna Instruments HI 96724C User manual

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www.hannainst.com
This Instrument is in
Compliance with the CE Directives
Instruction Manual
HI 96724C
Free & Total Chlorine
ISM

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TABLE OF CONTENTS
PRELIMINARY EXAMINATION .............................................................................................. 3
GENERAL DESCRIPTION ...................................................................................................... 4
ABBREVIATIONS ................................................................................................................ 4
SPECIFICATIONS ................................................................................................................ 5
PRECISION AND ACCURACY ................................................................................................. 5
PRINCIPLE OF OPERATION .................................................................................................. 6
FUNCTIONAL DESCRIPTION ................................................................................................7
ERRORS AND WARNINGS ..................................................................................................9
GENERAL TIPS FOR AN ACCURATE MEASUREMENT ...........................................................11
STARTUP...................................................................................................................12
MEASUREMENT PROCEDURE ...........................................................................................12
VALIDATION PROCEDURE .................................................................................................15
CALIBRATION PROCEDURE ...............................................................................................17
GLP...........................................................................................................................20
BATTERY MANAGEMENT ..................................................................................................21
BATTERY REPLACEMENT ..................................................................................................22
ACCESSORIES .................................................................................................................22
WARRANTY .................................................................................................................23
Dear Customer,
Thank you for choosing a Hanna product. This manual will provide you with the necessary
information for the correct use of the instrument. Please read it carefully before using the meter. If
you need additional technical information, do not hesitate to e-mail us at [email protected].
This instrument is in compliance with directives.
All rights are reserved. Reproduction in whole or in part is prohibited without the written consent of the copyright owner,
Hanna Instruments Inc., Woonsocket, Rhode Island, 02895 , USA.

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PRELIMINARY EXAMINATION
Please examine this product carefully. Make sure that the instrument is not damaged. If any
damage occurred during shipment, please notify your Dealer.
Each HI 96724 Ion Selective Meter is supplied complete with:
• Two Sample Cuvets and Caps
• 9V Battery
• Tissue for wiping cuvets
• Instrument quality certificate
• Instruction Manual
• Rigid carrying case
Note:Save all packing material until you are sure that the instrument works correctly. Any
defective item must be returned in its original packing.

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GENERAL DESCRIPTION
ABBREVIATIONS
The HI 96724 is an auto diagnostic portable microprocessor meter that benefits from Hanna’s
years of experience as a manufacturer of analytical instruments. It has the advanced optical
system based on a special tungsten lamp and a narrow band interference filter that allows most
accurate and repeatable readings. All instruments are factory calibrated and the electronic and
optical design minimizes the need of frequent calibration.
With the powerful CAL CHECKTM validation function, you are able to validate good performance
of your instrument at any time. The validation procedure is extremely user friendly. Just use the
exclusive HANNA ready-made, NIST traceable standards to verify the performance of the
instrument and recalibrate if necessary.
All instruments are splash waterproof and the lamp and filter units are protected from dust or dirt
by a transparent cup. This makes the instruments fulfill field applications. Display messages aid
the user in routine operation. The meter has an auto-shut off feature that will turn off the
instrument after 10 minutes of non use in measurement mode or after 1 hour if left in
calibration mode.
The meter uses an exclusive positive-locking system to ensure that the cuvet is in the same
position every time it is placed into the measurement cell. It is designed to fit a cuvet with a
larger neck making it easier to add both sample and reagents. The cuvet is made from special
optical glass to obtain best results.
The HI 96724 meter measures the free and total chlorine (Cl2) content in water samples in the
0.00 to 5.00 mg/L (ppm) range. The method is an adaptation of the USEPA Method 330.5 for
wastewater, and Standard Method 4500-Cl G for drinking water.
The reagents are in liquid form and are supplied in dropper bottles. The amount of reagent is
precisely dosed to ensure the maximum repeatability.
degree Celsius
US Environmental Protection Agency
degree Fahrenheit
milligrams per liter. mg/L is equivalent to ppm (part per million)
milliliter
millivolts
°C:
EPA:
°F:
mg/L:
mL:
mV:

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SPECIFICATIONS
PRECISION AND ACCURACY
Range 0.00 to 5.00 mg/L of Cl2(Free or Total)
Resolution 0.01 mg/L from 0.00 to 3.50 mg/L; 0.10 mg/L above 3.50 mg/L
Precision ±0.03 mg/L @ 1.00 mg/L
Typical EMC Deviation ±0.01 mg/L
Light Source Tungsten lamp
Light Detector Silicon Photocell with narrow band interference filter @ 525 nm
Method Adaptation of the USEPA method 330.5 and Standard Method 4500-Cl G.
The reaction between chlorine and the reagents causes a pink tint in
the sample.
Environment 0 to 50°C (32 to 122°F); max 95% RH non-condensing
Battery Type 1 x 9 volt
Auto-Shut off After 10' of non-use in measurement mode;
after 1 hour of non-use in calibration mode;
with last reading reminder.
Dimensions 192 x 102 x 67 mm (7.6 x 4 x 2.6")
Weight 290 g (10 oz.).
REQUIRED REAGENTS
Code Description Quantity/test
HI 93701A-T DPD1 Indicator 3 drops
HI 93701B-T DPD1 Buffer 3 drops
HI 93701C-T DPD3 Solution 3 drops
Precision is how closely repeated measurements
agree with each other. Precision is usually
expressed as standard deviation (SD).
Accuracy is defined as the nearness of a test
result to the true value.
Although good precision suggests good accuracy,
precise results can be inaccurate. The figure
explains these definitions.
In a laboratory using a standard solution of 1.00
mg/L chlorine and a representative lot of reagents,
an operator obtained with a single instrument a
standard deviation of 0.03 mg/L.

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PRINCIPLE OF OPERATION
Absorption of Light is a typical phenomenon of interaction between electromagnetic radiation and
matter. When a light beam crosses a substance, some of the radiation may be absorbed by
atoms, molecules or crystal lattices.
If pure absorption occurs, the fraction of light absorbed depends both on the optical path length
through the matter and on the physical-chemical characteristics of the substance according to the
Lambert-Beer Law:
-log I/Io= ελc d
or
A = ελc d
Where:
-log I/Io= Absorbance (A)
Io= intensity of incident light beam
I= intensity of light beam after absorption
ελ= molar extinction coefficient at wavelength λ
c = molar concentration of the substance
d = optical path through the substance
Therefore, the concentration "c" can be calculated from the absorbance of the substance as the
other factors are known.
Photometric chemical analysis is based on the possibility to develop an absorbing compound
from a specific chemical reaction between sample and reagents. Given that the absorption of a
compound strictly depends on the wavelength of the incident light beam, a narrow spectral
bandwidth should be selected as well as a proper central wavelength to optimize measurements.
The optical system of Hanna's HI 96 series colorimeters is based on special subminiature
tungsten lamps and narrow-band interference filters to guarantee both high performance and
reliable results.
HI 96 series block diagram (optical layout)

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1) GLP/ key
2) CAL CHECK key
3) ZERO/CFM key
4) READ/ key
5) ON/OFF key
6) Liquid Cristal Display (LCD)
7) Cuvet alignment indicator
8) Cuvet holder
FUNCTIONAL DESCRIPTION
A microprocessor controlled special tungsten lamp emits radiation which is first optically
conditioned and beamed to the sample contained in the cuvet. The optical path is fixed by the
diameter of the cuvet. Then the light is spectrally filtered to a narrow spectral bandwidth, to
obtain a light beam of intensity Ioor I.
The photoelectric cell collects the radiation Ithat is not absorbed by the sample and converts
it into an electric current, producing a potential in the mV range.
The microprocessor uses this potential to convert the incoming value into the desired measuring
unit and to display it on the LCD.
The measurement process is carried out in two phases: first the meter is zeroed and then the
actual measurement is performed.
The cuvet has a very important role because it is an optical element and thus requires particular
attention. It is important that both, the measurement and the calibration (zeroing) cuvets, are
optically identical to provide the same measurement conditions. Whenever possible use the same
cuvet for both. It is necessary that the surface of the cuvet is clean and not scratched. This to
avoid measurement interference due to unwanted reflection and absorption of light. It is
recommended not to touch the cuvet walls with hands.
Furthermore, in order to maintain the same conditions during the zeroing and the measuring
phases, it is necessary to close the cuvet to prevent any contamination.
INSTRUMENT DESCRIPTION

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KEYPAD DESCRIPTION
•ON/OFF: to turn the meter on and off.
•ZERO/CFM: to zero the meter prior to measurement, to confirm edited values or to confirm
factory calibration restore.
•READ/ : this is a bi-functional key. In measurement mode, press to make a measurement. In
GLP mode press to view the next screen.
•CAL CHECK: this is a bi-functional key. Just press to perform the validation of the meter, or
press and hold for three seconds to enter calibration mode.
• GLP/: this is a bi-functional key. Just press to enter GLP mode. In calibration mode press
to edit the date and time.
OPERATING MODES
•Measurement mode: default operation mode, enables both validation and measurement.
•Calibration mode: may be entered by keeping CAL CHECK pressed for three seconds (the
“CAL” tag appears), it enables calibration of the instrument.
•GLP mode may be entered by pressing GLP/(“GLP” appears), it enables consulting of
user calibration date or restore factory calibration.
DISPLAY ELEMENTS DESCRIPTION
1) The measuring scheme (lamp, cuvet, detector), appears during different phases of zero or
reading measurement
2) Error messages and warnings
3) The battery icon shows the charging level of the battery
4) The hourglass appears when an internal checking is in progress
5) Status messages
6) The chronometer appears when the reaction timer is running
7) The month, day and date icons appear when a date is displayed
8) Four digit main display
9) Measuring units
10) Four digit secondary display

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ERRORS AND WARNINGS
The instrument shows clear messages when erroneous condition appears. Messages are also displayed
when the obtained values are outside expected range. The beeper is playing a beep on errors.
a) on zero reading
Light High: There is too much light to perform a measurement.
Please check the preparation of the zero cuvet.
Light Low: There is not enough light to perform a measurement.
Please check the preparation of the zero cuvet.
No Light:The instrument cannot adjust the light level. Please
check that the samples does not contain any debris.
Inverted cuvets: The sample and the zero cuvet are inverted.
Zero: A zero reading was not taken. Follow the instructions of
the measurement procedure for zeroing the meter.
b) on sample reading

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Under range: A blinking “0.00” indicates that the sample
absorbs less light than the zero reference. Check the procedure
and make sure you use the same cuvet for reference (zero) and
measurement.
Over Range: A flashing value of the maximum concentration
indicates an over range condition. The concentration of the
sample is beyond the programmed range: dilute the sample and
re-run the test.
c) during calibration procedure
Standard Low: The standard reading is less than expected.
Standard High: The standard reading is higher than expected.
Cooling lamp: The instrument waits for the lamp to cool down.
d) other errors and warnings
Battery low: The battery must be replaced soon.

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The instructions listed below should be carefully followed during testing to ensure best accuracy.
• Color or suspended matter in large amounts may cause
interference, therefore these should be removed by
treatment with active carbon and by prior filtration.
• For a correct filling of the cuvet: the liquid in the cuvet
forms a concavity on the top; the bottom of this concavity
must be at the same level of the 10 mL mark.
• Proper use of dropper:
(a) to get good reproducible results, tap the dropper on the table for several times and wipe
the outside of the dropper with a cloth.
(b) always keep the dropper bottle in a vertical position while dosing the reagent.
• It is important that the sample does not contain any debris. This would corrupt the reading.
GENERAL TIPS FOR AN ACCURATE MEASUREMENT
Dead battery: This indicates that the battery is dead and must
be replaced. Once this indication is displayed, the meter will
lock up. Change the battery and restart the meter.
(a) (b)

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• Whenever the cuvet is placed into the measurement cell, it
must be dry outside, and completely free of fingerprints, oil
or dirt. Wipe it thoroughly with HI 731318 or a lint-free
cloth prior to insertion.
• Shaking the cuvet can generate bubbles in the sample, causing higher readings. To obtain
accurate measurements, remove such bubbles by swirling or by gently tapping the cuvet.
• Do not let the reacted sample stand too long after reagent is added, or accuracy will be lost.
• It is possible to take multiple readings in a row, but it is recommended to take a new zero
reading for each sample and to use the same cuvet for zeroing and measurement.
• After the reading it is important to discard immediately the sample, otherwise the glass
might become permanently stained.
• All the reaction times reported in this manual are referred to 20°C (68°F). As a general rule
of thumb, they should be doubled at 10°C (50°F) and halved at 30°C (86°F).
• In order to maximize accuracy, prior to a measurement follow the validation procedure to
be sure that the instrument is properly calibrated. If necessary, calibrate the instrument.
• In order to avoid reagent leaking and to obtain more accurate
measurements, it is recommended to close the cuvet first with
the supplied HPDE plastic stopper and then with the black
cap.
STARTUP
Prepare the instrument for measurement as follows:
• Unpack the instrument by removing the dust protection sleeve from the instrument cuvet holder.
• Place the battery in the instrument as described in the “BATTERY REPLACEMENT” chapter.
• Place the instrument on a flat table.
• Do not place the instrument under direct sun light.
• Each time the cuvet is used, the cap must be tightened to the
same degree.

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To compensate the meter for the sample turbidity or color, the measurement takes place in two
phases. First, the meter is zeroed using the unreacted sample. After the reagents are added the
reacted sample is measured.
• When the beeper sounds briefly and the
LCD displays dashes, the meter is ready.
The blinking “ZERO” indicates that the
instrument needs to be zeroed first.
• Fill the cuvet with 10 mL of unreacted
sample, up to the mark, and replace the
cap.
• Place the cuvet into the cuvet holder and
ensure that the notch on the cap is
positioned securely into the groove.
• Press ZERO/CFM and the lamp, cuvet
and detector icons will appear on the
display, depending on the measurement
phase.
• After a few seconds, the display will show
“-0.0-”. The meter is now zeroed and
ready for measurement.
MEASUREMENT PROCEDURE
•Turn the meter on by pressing ON/OFF.
The display briefly shows all tags on.

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• Remove the cuvet.
•For free chlorine measurement: add 3
drops of HI 93701A-T DPD1 indicator
and 3 drops of HI 93701B-T DPD1 buffer
to the cuvet.
Immediately add 10 mL of unreacted
sample. Replace the cap and shake gently.
•Immediately replace the cuvet into the
cuvet holder and ensure that the notch on
the cap is positioned securely into the
groove.
• Press READ/ and the lamp, cuvet and
detector icons will appear on the display,
depending on the measurement phase.
• At the end of measurement, the instrument
directly displays concentration in mg/L of
free chlorine on the LCD.
•For total chlorine measurement,remove
the cuvet and add to the reacted sample
3 drops of HI 93701C-T DPD3 solution.
Replace the cap and swirl gently.
• Replace the cuvet into the cuvet holder
and ensure that the notch on the cap is
positioned securely into the groove.

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• Wait for 2’ and 30’’ and press READ/ .
The lamp, cuvet and detector icons will
appear on the display, depending on the
measurement phase.
• At the end of measurement, the instrument
directly displays concentration in mg/L of
total chlorine on the LCD.
INTERFERENCES
Bromine (positive error)
Chlorine dioxide (positive error)
Ozone (positive error)
Iodine (positive error)
Oxidized Manganese and Chromium (positive error)
VALIDATION PROCEDURE
Alkalinity above 250 mg/L CaCO3 or acidity above 150 mg/L CaCO3will not reliably develop the
full amount of color or it may rapidly fade. To resolve this, neutralize the sample with diluted
HCl or NaOH.
In case of water with hardness greater than 500 mg/L CaCO3, shake the sample for approximately
2 minutes after adding the powder reagent.
Use the validation procedure to ensure that the instrument is properly calibrated.
Warning: Do not validate the instrument with any standard solutions other than the HANNA CAL
CHECKTM Standards, otherwise erroneous results will be obtained. For accurate validation, please
perform test at room temperature: 18 to 25°C (64.5 to 77.0°F)
•Turn the meter on by pressing ON/OFF.
• When the beeper sounds briefly and the
LCD displays dashes, the meter is ready.

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• After a few seconds, the display will show
“-0.0-”. The meter is now zeroed and ready
for validation.
• Remove the cuvet.
• Place the CAL CHECKTM Standard HI 95724-11
Cuvet B into the cuvet holder and ensure that
the notch on the cap is positioned securely
into the groove.
• Press CAL CHECKTM and the lamp, cuvet and
detector icons together with “CAL CHECK” will
appear on the display, depending on the
measurement phase.
• At the end of the measurement the display
will show the validation standard value.
The reading should be within specifications as reported in the CAL CHECKTM Standard
Certificate. If the value is found out of the specifications, please check that the cuvets are free
of fingerprints, oil or dirt and repeat validation. If results are still found out of specifications,
then recalibrate the instrument.
• Press ZERO/CFM and the lamp, cuvet
and detector icons will appear on the
display, depending on the measurement
phase.
• Place the CAL CHECKTM Standard
HI 95724-11 Cuvet A into the cuvet
holder and ensure that the notch on the
cap is positioned securely into the groove.

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CALIBRATION PROCEDURE
Note: It is possible to interrupt calibration procedure at any time by pressing CAL CHECK or
ON/OFF keys.
Warning: Do not calibrate the instrument with standard solutions other than the HANNA CAL
CHECKTM Standards, otherwise erroneous results will be obtained. For accurate calibration, please
perform test at room temperature: 18 to 25°C (64.5 to 77.0°F)
• Turn the meter on by pressing ON/OFF.
• When the beeper sounds briefly and the
LCD displays dashes, the meter is ready.
• Press and hold CAL CHECK for three
seconds to enter calibration mode. The
display will show “CAL” during
calibration procedure. The blinking
“ZERO” asks for instrument zeroing.
• Place the CAL CHECKTM Standard
HI 95724-11 Cuvet A into the cuvet
holder and ensure that the notch on the
cap is positioned securely into the groove.
• Press ZERO/CFM and the lamp, cuvet
and detector icons will appear on the
display, depending on the measurement
phase.

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• After a few seconds the display will show
“-0.0-”. The meter is now zeroed and ready
for calibration. The blinking “READ” asks for
reading calibration standard.
• Remove the cuvet.
• Place the CAL CHECKTM Standard HI 95724-11
Cuvet B into the cuvet holder and ensure that
the notch on the cap is positioned securely into
the groove.
• Press READ/ and the lamp, cuvet and
detector icons will appear on the display,
depending on the measurement phase.
• After measurement the instrument will show
for three seconds the Cal Check Standard value.
Note: If the display shows “STD HIGH”, the
standard value was too high. If the display
shows “STD LOW”, the standard value was
too low. Verify that both CAL CHECKTM
Standards HI 95724-11 Cuvets, A and B are
free from fingerprints or dirt and that they are
inserted correctly.
Then the date of the last calibration (e.g.:
”01.08.2005”) appears on the display, or
“01.01.2005” if the factory calibration was
selected before. In both cases the year number
is blinking, ready for date input.

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• Press GLP/ to edit the desired day
(01-31). If the key is kept pressed the
day number is automatically increased.
Note: It is possible to change the editing
from day to year and to month by pressing
READ/ .
• Press GLP/ to edit the desired year
(2000-2099). If the key is kept pressed,
the year number is automatically
increased.
• When the correct year has been set, press
ZERO/CFM or READ/ to confirm. Now
the display will show the month blinking.
• Press GLP/ to edit the desired month
(01-12). If the key is kept pressed the
month number is automatically increased.
• When the correct month has been set,
press ZERO/CFM or READ/ to confirm.
Now the display will show the day
blinking.
• Press ZERO/CFM to save the calibration
date.
• The instrument displays “Stor” for one
second and the calibration is saved.
DATE INPUT
or
or

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In the GLP mode, the last user calibration date can be consulted and the factory calibration can
be restored.
To display the calibration date:
• Press GLP/ to enter GLP mode. The
calibration month and day will appear on
the main display and the year on the
secondary display.
LAST CALIBRATION DATE
• If no calibration was performed, the
factory calibration message, “F.CAL” will
appear on the main display and the
instrument returns to measurement mode
after three seconds.
FACTORY CALIBRATION RESTORE
It is possible to delete the calibration and
restore factory calibration.
• Press GLP/ to enter GLP mode.
GLP
• The instrument will return automatically
to the measurement mode by displaying
dashes on the LCD.