Hanna Instruments HI96725C User manual

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INSTRUCTION MANUAL
HI96725C
Chlorine, Cyanuric Acid & pH ISM

Thank you for choosing a Hanna Instruments product.
Please read this instruction manual carefully before using the instrument.
This manual will provide you with the necessary information for correct use of
the instrument, as well as a precise idea of its versatility.
If you need additional technical information, do not hesitate to e‑mail us at
[email protected] or view our worldwide contact list at www.hannainst.com.
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.
Dear
Customer,

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PRELIMINARY EXAMINATION ............................................................................................
GENERAL DESCRIPTION ....................................................................................................
ABBREVIATIONS ..............................................................................................................
SPECIFICATIONS ..............................................................................................................
PRECISION AND ACCURACY ..............................................................................................
PRINCIPLE OF OPERATION ...............................................................................................
FUNCTIONAL DESCRIPTION ...............................................................................................
ERRORS AND WARNINGS .................................................................................................
GENERAL TIPS FOR AN ACCURATE MEASUREMENT .............................................................
STARTUP ........................................................................................................................
RANGE SELECTION............................................................................................................
MEASUREMENT PROCEDURE ............................................................................................
VALIDATION PROCEDURE .................................................................................................
CALIBRATION PROCEDURE ...............................................................................................
GLP ................................................................................................................................
BATTERY MANAGEMENT ...................................................................................................
BATTERY REPLACEMENT ...................................................................................................
ACCESSORIES ..................................................................................................................
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TABLE OF CONTENTS
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heckTM
Please examine this product carefully. Make sure that the instrument is not damaged. If any damage
occurred during shipment, please contact your local Hanna Instruments Office.
Each HI96725 Ion Selective Meter is supplied complete with:
• Sample Cuvettes and Caps (2 pcs.)
• CAL CheckTM Standard Cuvettes (5 pcs.)
• 9V Battery
• Scissors
• Cloth for wiping cuvettes
• Instruction Manual and Quick Reference Guide
• Quality Certificate
• 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.
PRELIMINARY EXAMINATION

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The HI96725 is an auto diagnostic portable microprocessor meter that benefits from Hanna
Instruments’ years of experience as a manufacturer of analytical instruments. It has an 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 Instruments ready‑made, NIST traceable standards to verify the performance of
the instrument and recalibrate if necessary.
All instruments are splash proof 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 cuvette is in the same
position every time it is placed into the measurement cell. It is designed to fit a cuvette with a
larger neck making it easier to add both sample and reagents. The cuvette is made from special
optical glass to obtain best results.
The HI96725 meter measures the pH value in the 6.5 to 8.5 range, the free and total chlorine
(Cl2) in water samples in the 0.00 to 5.00 mg/L (ppm) range, and cyanuric acid in the 0 to
80 mg/L range. The methods are phenol red for pH, an adaptation of the USEPA Method 330.5
for wastewater, and Standard Method 4500‑Cl G for drinking water for free and total chlorine and
an adaptation of the turbidimetric method for cyanuric acid.
The reagents are in powder and liquid form and supplied in packets or 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 (parts per million)
milliliter
millivolt
°C:
USEPA:
°F:
mg/L:
mL:
mV:
GENERAL DESCRIPTION ABBREVIATIONS

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Range
Free Cl2 0.00 to 5.00 mg/L
Total Cl2 0.00 to 5.00 mg/L
Cyanuric Acid 0 to 80 mg/L
pH 6.5 to 8.5
Resolution
0.01 mg/L under 3.50 mg/L Chlorine
0.10 mg/L above 3.50 mg/L Chlorine
1 mg/L Cyanuric Acid
0.1 pH
Accuracy
@25 °C (77 °F)
Free Cl2 ±0.03 mg/L ±3% of reading
Total Cl2 ±0.03 mg/L ±3% of reading
Cyanuric Acid ±1 mg/L±15% of reading
pH ±0.1 pH
Light source Tungsten lamp
Light Detector Silicon Photocell @525 nm filter
Method
For Cl2: Adaptation of the USEPA method and Standard Method 4500‑Cl G. The re‑
action with reagents causes a pink tint in the sample.For Cyanuric Acid: Adaptation
of the turbidimetric method. The reaction between cyanuric acid and the reagent
causes a white suspension in the sample. For pH: Phenol red method. The reaction
with reagents causes a red tint in the sample.
Environment 0 to 50 °C (32 to 122 °F); max 95% RH non‑condensing
Battery Type 9V (1 pc.)
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 104 x 69 mm (7.6 x 4.1 x 2.7”)
Weight 320 g (11.3 oz.)
Required Reagents
Code Unit Description Quantity/Test
HI93701-0 Free Cl2 DPD Powder Reagent 1 packet
HI93711-0 Total Cl2 DPD Powder Reagent 1 packet
HI93722-0 Cyanuric Acid 1 packet
HI93710-0 pH 5 drops
SPECIFICATIONS

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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
ε
λ= molar extinction coefficient at wavelength λ
c = molar concentration of the substance
d = optical path through the substance
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 reagent, an operator obtained
with a single instrument a standard deviation of
0.02 mg/L.
PRECISION AND ACCURACY PRINCIPLE OF OPERATION

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A microprocessor controlled special tungsten lamp emits radiation which is first optically conditioned
and beamed to the sample contained in the cuvette. The optical path is fixed by the diameter of
the cuvette. 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 cuvette 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) cuvettes, are
optically identical to provide the same measurement conditions. Whenever possible use the same
cuvette for both. It is necessary that the surface of the cuvette 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 cuvette walls with hands.
Furthermore, in order to maintain the same conditions during the zeroing and the measuring phases,
it is necessary to close the cuvette to prevent any contamination.
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 Instruments’ HI96 series colorimeters is based on special subminiature
tungsten lamps and narrow‑band interference filters to guarantee both high performance and
reliable results.
HI96 series block diagram (optical layout)
PRINCIPLE OF OPERATION

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1) RANGE/GLP key
2) CAL CHECK key
3) ZERO/CFM key
4) READ /TIMER key
5) ON/OFF key
6) Liquid Crystal Display (LCD)
7) Cuvette alignment indicator
8) Cuvette holder
INSTRUMENT DESCRIPTION
KEYPAD DESCRIPTION
• ON/OFF: to turn the meter on and off.
• ZERO/CFM: this is a bi‑functional key. Just press to zero the meter prior to measurement, or
confirm edited values. In calibration mode press to confirm factory calibration restore.
• READ /TIMER: this is a multi‑functional key. In measurement mode, press to make a
measurement, or press and hold for three seconds to start a pre‑programmed countdown prior
to 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.
• RANGE/GLP : this is a multi‑functional key. Just press to change the parameter. Press and
hold for three seconds to enter GLP mode. In calibration mode press to edit the date and time.
FUNCTIONAL DESCRIPTION

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DISPLAY ELEMENTS DESCRIPTION
1) The measuring scheme (lamp, cuvette, detector), appears during different phases of zero or
reading measurement
2) Error messages and warnings
3) The battery icon indicates the charge state of the battery
4) The hourglass appears when an internal check 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
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 keeping RANGE/GLP pressed for three seconds (“GLP”
appears), it enables consulting of user calibration date or restore factory calibration.
FUNCTIONAL DESCRIPTION

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The instrument shows clear messages when erroneous conditions appear. 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 cuvette.
Light Low: There is not enough light to perform a measurement.
Please check the preparation of the zero cuvette.
No Light: The instrument cannot adjust the light level. Please check
that the sample does not contain any debris.
Inverted cuvettes: The sample and the zero cuvette are inverted.
Zero: A zero reading was not taken. Follow the instructions of the
measurement procedure for zeroing the meter.
b) on sample reading
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 cuvette for reference (zero) and measurement.
ERRORS AND WARNINGS

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Battery low: The battery must be replaced soon.
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.
Cap error: Appears when external light enters in the analysis cell.
Assure that the cuvette cap is present.
Cooling lamp: The instrument waits for the lamp to cool down.
d) other errors and warnings
ERRORS AND WARNINGS

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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 cuvette: the liquid in the cuvette
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 the powder reagent packet:
(a) use scissors to open the powder packet;
(b) push the edges of the packet to form a spout;
(c) pour out the content of the packet
Dead battery: This indicates that the battery is dead and must
be replaced. Once this indication is displayed, normal operation of
the instrument will be interrupted. Change the battery and restart
the meter.
GENERAL TIPS FOR AN ACCURATE MEASUREMENT
• 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.

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Prepare the instrument for measurement as follows:
• Unpack the instrument by removing the dust protection sleeve from the instrument cuvette
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.
• It is important that the sample does not contain any debris. This would corrupt the reading.
• Each time the cuvette is used, the cap must be tightened to the same degree.
• Whenever the cuvette is placed into the measurement cell, it must be dry outside, and completely
free of fingerprints, oil or dirt. Wipe it thoroughly with HI731318 or a lint‑free cloth prior to
insertion.
• Shaking the cuvette can generate bubbles in the sample, causing higher readings. To obtain
accurate measurements, remove such bubbles by swirling or by gently tapping the cuvette.
• 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 cuvette 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 25 °C (77 °F). In general, the
reaction time should be increased for temperatures lower than 20 ºC (68 ºF), and decreased
for temperatures higher than 25 ºC (77 ºF).
• 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.
GENERAL TIPS FOR AN ACCURATE MEASUREMENTSTARTUP

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• Press RANGE/GLP to change the range.
The range can be changed any time when the instrument is in measurement mode.
The selected range is memorized and the selection remains unchanged at power off or when the
battery is removed.
The HI96725 can measure Free Chlorine when range P1 is selected, Total Chlorine when range
P2 is selected, Cyanuric Acid when P3 is selected or pH when P4 is selected. To change the active
range follow the procedure:
• Turn the meter on by pressing ON/OFF. The display briefly shows all tags on.
• After startup, the range identification number is shown on the secondary display as P1, P2, P3
or P4.
RANGE SELECTION
Code Parameter
P1 Free Chlorine
P2 Total Chlorine
P3 Cyanuric Acid
P4 pH

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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.
Important note:Free and Total Chlorine have to be measured separately with fresh unreacted
samples if both values are requested.
• Turn the meter on by pressing ON/OFF. The display briefly shows all tags on.
• 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.
• Pay attention to the selected range. To change the range, simply press RANGE/GLP .
• Fill the cuvette with 10 mL of unreacted sample, up to the mark, and replace the cap.
• Place the cuvette into the cuvette holder and ensure that the notch on the cap is positioned
securely into the groove.
MEASUREMENT PROCEDURE

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• Press ZERO/CFM and the lamp, cuvette 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.
• Remove the cuvette.
• Add the specific test reagent for each parameter:
Free Chlorine: 1 packet of HI93701‑0. Replace the cap and shake gently for 20 seconds.
Total Chlorine: 1 packet of HI93711‑0. Replace the cap and shake gently for 20 seconds.
Cyanuric Acid: Fill a beaker with 25 mL of sample, add 1 packet of HI93722‑0 and swirl
gently. Fill a second cuvette with 10 mL of reacted sample.
pH: 5 drops of HI93710‑0. Replace the cap and swirl the solution.
• Replace the cuvette into the holder and ensure that the notch on the cap is positioned securely
into the groove.
MEASUREMENT PROCEDURE
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or or

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• At the end of measurement, the instrument directly displays concentration in mg/L of free chlorine,
total chlorine or cyanuric acid or the pH measured value and the range number on the LCD.
INTERFERENCES FOR FREE CHLORINE AND TOTAL CHLORINE
Bromine, Oxidized Manganese and Chromium, Chlorine dioxide, Ozone and Iodine (positive error).
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.
• Alternatively, wait for:
Free Chlorine: 1 minute; Total Chlorine: 2 minutes and 30 seconds, Cyanuric Acid: 45
seconds, pH: press READ /TIMER directly.
Press READ /TIMER. In all cases the lamp cuvette and detector icons will appear on the
display, depending on the measurement phase.
or
• Press and hold READ /TIMER for three seconds. The display will show the countdown prior
to measurement. The beeper is playing a beep at the end of the countdown period.
MEASUREMENT PROCEDURE
or
1'
2'30"
3"

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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 Instruments
CAL CheckTM Standards, otherwise erroneous results will be obtained.
Note: The validation is performed only for the selected parameter. For full validation of the
instrument, the following procedure must be performed for each parameter.
• Turn the meter on by pressing ON/OFF.
• When the beeper sounds briefly and the LCD displays dashes, the meter is ready.
• Place the CAL CheckTM Standard Cuvette A into the cuvette holder and ensure that the notch
on the cap is positioned securely into the groove.
VALIDATION PROCEDURE
• Press ZERO/CFM and the lamp, cuvette 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
validation.

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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 cuvettes are free of fingerprints,
oil or dirt and repeat validation. If results are still found out of specifications, then recalibrate the
instrument.
• Remove the cuvette.
• Place the specific CAL CheckTM Standard Cuvette B into the cuvette holder, for:
Free Chlorine:B, HI96701‑11
Total Chlorine:B, HI96711‑11
Cyanuric Acid: B, HI96722‑11
pH: B, HI96710‑11
Ensure that the notch on the cap is positioned securely into the groove.
• Press CAL CheckTM and the lamp, cuvette 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.
VALIDATION PROCEDURE