Hanna Instruments HI97725 User manual

INSTRUCTION MANUAL
HI97725
Free Chlorine,
Total Chlorine,
Cyanuric Acid & pH
Photometer

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.
Thank you for choosing a Hanna Instruments product.
Please read this instruction manual carefully before using this instrument.
This manual will provide you with the necessary information for correct
use of this 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.
Dear
Customer,

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TABLE OF CONTENTS
TABLE OF CONTENTS
1. PRELIMINARY EXAMINATION ..........................................................................4
2. SAFETY MEASURES........................................................................................5
3. ABBREVIATIONS ...........................................................................................5
4. SPECIFICATIONS............................................................................................6
5. DESCRIPTION................................................................................................7
5.1. GENERAL DESCRIPTION & INTENDED USE..............................................7
5.2. FUNCTIONAL DESCRIPTION...................................................................8
5.3. PRECISION & ACCURACY.......................................................................9
5.4. PRINCIPLE OF OPERATION....................................................................9
5.5. OPTICAL SYSTEM................................................................................10
6. GENERAL OPERATIONS.................................................................................11
6.1. METER VALIDATION: CAL CHECK & CALIBRATION...................................11
6.2. GLP...................................................................................................13
6.3. LOGGING DATA & LOG RECALL ............................................................. 13
6.4. GENERAL SETUP ................................................................................14
6.5. REAGENTS & ACCESSORIES.................................................................16
6.6. CONTEXTUAL HELP............................................................................. 17
6.7. BATTERY MANAGEMENT ..................................................................... 17
7. PHOTOMETER..............................................................................................18
7.1. METHOD SELECTION .......................................................................... 18
7.2. COLLECTING & MEASURING SAMPLES AND REAGENTS...........................18
7.3. CUVETTE PREPARATION...................................................................... 19
8. METHOD PROCEDURE ..................................................................................20
8.1. FREE CHLORINE (POWDER REAGENT) .................................................. 20
8.2. FREE CHLORINE (LIQUID REAGENT)..................................................... 22
8.3. TOTAL CHLORINE (POWDER REAGENT).................................................25
8.4. TOTAL CHLORINE (LIQUID REAGENT) ...................................................27
8.5. CYANURIC ACID..................................................................................30
8.6. pH.................................................................................................... 32
9. WARNING & ERROR DESCRIPTIONS...............................................................34
10. BATTERY REPLACEMENT ............................................................................. 36
11. ACCESSORIES............................................................................................ 37
11.1. REAGENT SETS.................................................................................37
11.2. OTHER ACCESSORIES .......................................................................37
CERTIFICATION.................................................................................................38
RECOMMENDATIONS FOR USERS.......................................................................38
WARRANTY ......................................................................................................38

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PRELIMINARY EXAMINATION
1. PRELIMINARY EXAMINATION
Remove the instrument and accessories from the packaging and examine it carefully.
For further assistance, please contact your local Hanna Instruments Office or email us
at [email protected].
Each HI97725C is delivered in a rugged carrying case and is supplied with:
• Sample cuvette (2 pcs.)
• Sample cuvette cap (2 pcs.)
• Plastic stopper (2 pcs.)
• A ZERO - CAL Check Cuvette A
• HI97701B - CAL Check Cuvette B for Free and Total Chlorine (Powder & Liquid)
• HI97710B - CAL Check Cuvette B for pH
• HI97722B - CAL Check Cuvette B for Cyanuric Acid
• Cloth for wiping cuvettes
• Scissors
• 1.5V AA Alkaline batteries
• CAL Check standard certificate
• Instrument quality certificate
• Instruction manual
Each HI97725 is delivered in a cardboard box and is supplied with:
• Sample cuvette (2 pcs.)
• Sample cuvette cap (2 pcs.)
• Plastic stopper (2 pcs.)
• 1.5V AA Alkaline batteries
• Instrument quality certificate
• Instruction manual
Note: Save all packing material until you are sure that the instrument works
correctly. Any damaged or defective item must be returned in its original packing
material with the supplied accessories.

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SAFETY MEASURES
2. SAFETY MEASURES
• The chemicals contained in the reagent kits may be hazardous if
improperly handled.
• Read the Safety Data Sheets (SDS) before performing tests.
• Safety equipment: Wear suitable eye protection and clothing when
required, and follow instructions carefully.
• Reagent spills: If a reagent spill occurs, wipe up immediately and rinse
with plenty of water. If reagent contacts skin, rinse the affected area
thoroughly with water. Avoid breathing released vapors.
• Waste disposal: For proper disposal of reagent kits and reacted samples,
contact a licensed waste disposal provider.
3. ABBREVIATIONS
mg/L milligrams per liter (ppm)
mL milliliter
°C degree Celsius
°F degree Fahrenheit
EPA US Environmental Protection Agency
GLP Good Laboratory Practice
HDPE High Density Polyethylene
LED Light Emitting Diode
NIST National Institute of Standards and Technology
ABBREVIATIONS

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SPECIFICATIONS
4. SPECIFICATIONS
Chlorine
(All Methods)
Range 0.00 to 5.00 mg/L (as Cl2)
Resolution 0.01 mg/L
Accuracy ±0.03 mg/L ±3% of reading at 25 °C
Method Adaptation of US EPA Method 330.5, DPD
Colorimetric Method
Cyanuric Acid
Range 0 to 80 mg/L (as CYA)
Resolution 1 mg/L
Accuracy ±1 mg/L ±15% of reading at 25 °C
Method Adaptation of the Turbidimetric Method
pH
Range 6.5 to 8.5 pH
Resolution 0.1 pH
Accuracy ±0.1 pH of reading at 25 °C
Method Adaptation of the Phenol Red Method
Measurement
System
Light source Light Emitting Diode
Bandpass filter 525 nm
Bandpass filter
bandwidth 8 nm
Bandpass filter
wavelength accuracy ±1.0 nm
Light detector Silicon photocell
Cuvette type Round 24.6 mm diameter (22 mm inside)
Additional
Specifications
Auto logging 50 readings
Display 128 x 64 pixel B/W LCD with backlight
Auto-off After 15 minutes of inactivity
(30 minutes before a READ measurement)
Battery type 1.5 V AA Alkaline (3 pcs.)
Battery life > 800 measurements (without backlight)
Environment 0 to 50 °C (32 to 122 °F);
0 to 100% RH, non-serviceable
Dimensions 142.5 x 102.5 x 50.5 mm (5.6 x 4.0 x 2.0")
Weight
(with batteries) 380 g (13.4 oz.)
Case ingress
protection rating IP67, floating case

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DESCRIPTION
5. DESCRIPTION
5.1. GENERAL DESCRIPTION & INTENDED USE
The HI97725 is an auto-diagnostic portable photometer that benefits from Hanna’s
years of experience as a manufacturer of analytical instruments. It has an advanced
optical system that uses a Light Emitting Diode (LED) and a narrow band interference
filter that allows for accurate and repeatable readings.
The optical system is sealed from outside dust, dirt and water. The meter uses an
exclusive positive-locking system to ensure that the cuvettes are placed into the holder
in the same position every time.
With the CAL Check™ functionality, users are able to validate the performance of the
instrument at any time and apply a user calibration (if necessary). Hanna Instruments
CAL Check cuvettes are made with NIST traceable standards.
The built-in tutorial mode guides users step-by-step through the measurement
process. It includes all steps required for sample preparation, the required reagents
and quantities.
The HI97725 meter measures four important parameters in the treatment and
disinfection of drinking water, waste water, and swimming pools.
Chlorine is a widely used disinfectant. In order for chlorine to be effective the pH of the
water should be less then pH 8.0. The method is an adaptation of the US EPA Method
330.5, DPD Colorimetric Method.
Cyanuric Acid is added to increase the life of chlorine, without it chlorine levels can be
reduced by up to 90% in hours when exposed to sunlight. The method is an adaptation
of the Turbidimetric Method.
The method for pH is an adaptation of the Phenol Red Method.
The HI97725 photometer is a compact and versatile meter suitable for field or bench
measurements, featuring a:
• Sophisticated optical system
• Meter validation using certified CAL Check cuvettes
• Tutorial mode guides the user step-by-step
• Auto logging
• Waterproof IP67, floating case
• GLP features

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DESCRIPTION
5.2. FUNCTIONAL DESCRIPTION
1. ON/OFF power button 3. Liquid Crystal Display (LCD) 5. Indexing mark
2. Keypad 4. Cuvette holder 6. Battery cover
Keypad Description
The keypad contains 3 direct keys and 3 functional keys with the following functions:
Press the functional key to perform the function displayed above it on the LCD.
Press and hold to power off/on. Press briefly to return to the previous screen.
Press to access the menu screen.
Press to display the context-sensitive help menu.

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DESCRIPTION
5.3. PRECISION & ACCURACY
Precision is how closely repeated measurements are to one another. Precision is usually
expressed as standard deviation (SD).
Accuracy is defined as the closeness of a test result to the true value and is method
specific.
Although good precision suggests good accuracy, precise results can be inaccurate. The
figure explains these definitions.
5.4. 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. Photometric chemical analysis
is based on specific chemical reactions between a sample and reagent to produce a
light-absorbing compound.
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. If all other factors are constant, the
concentration "c" can be calculated form the absorbance of the substance.
Lambert-Beer Law:
-log I/Io= elc d
or
A = elc d
Io= intensity of incident light beam
I= intensity of light beam after absorption
el= molar extinction coefficient at wavelength l
c = molar concentration of the substance
d = optical path through the substance

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DESCRIPTION
5.5. OPTICAL SYSTEM
Instrument Block Diagram
The internal reference system (reference detector) of the HI97725 photometer
compensates for any drifts due to power fluctuations or ambient temperature changes,
providing a stable source of light for your blank (zero) measurement and sample
measurement.
LED light sources offer superior performance compared to tungsten lamps. LEDs have
a much higher luminous efficiency, providing more light while using less power. They
also produce little heat, which could otherwise affect electronic stability. LEDs are
available in a wide array of wavelengths, whereas tungsten lamps have poor blue/
violet light output.
Improved optical filters ensure greater wavelength accuracy and allow a brighter,
stronger signal to be received. The end result is higher measurement stability and less
wavelength error.
A focusing lens collects all of the light that exits the cuvette, eliminating errors from
cuvette imperfections and scratches, eliminating the need to index the cuvette.

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GENERAL OPERATIONS
6. GENERAL OPERATIONS
6.1. METER VALIDATION: CAL CHECK & CALIBRATION
Validation of the HI97725 involves verifying the concentration of the certified CAL Check
standards. The CAL Check screen guides the user step-by-step through the validation
process and user calibration (if necessary).
WARNING: Do not use any solutions or standards other than the Hanna
Instruments®CAL Check Standards. For accurate validation and calibration results,
please perform these at room temperature, 18 to 25 ° C (64.5 to 77.0 ° F).
Note: CAL Check Standards will not read the specified value in measurement
mode. Protect the CAL Check cuvettes from direct sunlight by keeping them in
the original packing. Store between 5 and 30
° C (41 to 86 ° F), do not freeze.
To perform a CAL Check:
1. Press the key to enter menu. Use the functional keys to select
CAL Check / Calibration and press Select.
The “Not Available“message or the date, time and status of the last CAL Check
will be displayed on the screen.
Note: CAL Check & Calibration is for the selected method.
2. Press Check to start a new CAL Check. Press the key at any time to abort
the validation process.
3. Use the functional keys to enter the certificate value of the calibration standard
found on the CAL Check Standard Certificate. Press Next to continue.
Note: This value will be saved in the instrument for future validation. If a new set
of calibration standards is obtained please update the certificate value.

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GENERAL OPERATIONS
4. Insert the A ZERO CAL Check Cuvette A then press Next to continue. The “Please
wait...“message will be displayed during the measurement.
5. Insert the CAL Check Cuvette B for the selected method (HI97701B for Free and
Total Chlorine, HI97722B for Cyanuric Acid or HI97710B for pH) then press
Next to continue. The “Please wait...“message will be displayed during the
measurement.
6. When the CAL Check is complete the display will show one of the following
messages and the value obtained during the measurement:
• “PASSED“: The measured value is within the accuracy specification, no user
calibration is required.
• “OUT OF SPECIFICATION“ and Calibrate is available: The measured value
is near the expected value. To update the user calibration press Calibrate. Press
Accept to confirm or Cancel to return to the previous screen.

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GENERAL OPERATIONS
• “OUT OF SPECIFICATION“: A user calibration is not allowed, the measured
value is outside of the tolerance window. Check the certified value, expiration date
and clean the outside of the cuvette. Repeat the CAL Check procedure. If this error
continues contact your nearest Hanna Instruments Customer Service Center.
6.2. GLP
Press the key to enter the menu. Use the functional keys to select GLP and
press Select. Good Laboratory Practice (GLP) shows the date and time of the last user
calibration (if available) or factory calibration. To erase the last user calibration and to
clear the CAL Check press Clear and follow the prompts. Press Yes to erase and return
to the factory calibration data or No to exit the clear procedure.
6.3. LOGGING DATA & LOG RECALL
The instrument features a data autolog function to help users keep track of all
measurements. Every time a measurement is made the data is automatically saved.
The data log can hold 50 individual measurements. When the data log is full (50 data
points) the meter will rewrite the oldest data point.
Viewing and deleting the data is possible using the Log Recall menu.
Press the key to enter the menu. Use the functional keys to select Log Recall
and press Select.
Use the functional keys to highlight a log and press Info to view additional information
about the log. From this screen Next and Previous can be used to view other logs.

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GENERAL OPERATIONS
Press Delete to erase logged data. After pressing Delete a prompt on display is asking
for confirmation.
Press No or the key to return to the previous screen.
Press Yes to delete selected log.
Press Del All to erase all the logged data. If Del All is pressed follow the prompt to
confirm. Press Yes to delete all logged data, No or the key to return to the log recall.
6.4. GENERAL SETUP
Press the key to enter the menu. Use the functional keys to select Setup and
press Select. Use the functional keys to highlight desired option.
Backlight
Option: 0 to 100 %
Press Modify to access the backlight intensity. Use the functional keys to increase or
decrease the value. Press Accept to confirm or the key to return to the Setup
menu without saving the new value.
Contrast
Option: 0 to 100 %
Press Modify to change the display’s contrast. Use the functional keys to increase or
decrease the value. Press Accept to confirm the value or the key to return to the
Setup menu without saving the new value.
Date & Time
Press Modify to change the date and time. Press the functional keys to highlight the
value to be modified (year, month, day, hour, minute or second). Press Edit to modify
the highlighted value. Use the functional keys to change the value.

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GENERAL OPERATIONS
Press Accept to confirm or the key to return to the previous screen.
Time Format
Option: AM/PM or 24-hour
Press the functional key to select the desired time format.
Date Format
Press Modify to change the date format. Use the functional keys to select the desired
format. Press Accept to confirm or the key to return to the Setup menu without
saving the new format.
Decimal Separator
Option: Comma ( , ) or Period ( . )
Press the functional key to select the desired decimal separator. The decimal separator
is used on the measurement screen.
Language
Press Modify to change the language. Use the functional keys to select the desired
language. Press Accept to choose one of the languages installed.

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GENERAL OPERATIONS
Beeper
Option: Enable or Disable
When enabled, a short beep is heard every time a key is pressed. A long beep alert
sounds when the pressed key is not active or an error is detected. Press the functional
key to enable or disable the beeper.
Tutorial
Option: Enable or Disable
When enabled, the user will be guided step-by-step through the measurement
procedure.
Meter Information
Press Select to view the model, serial number, firmware version and selected language.
Press the key to return to the Setup menu.
Restore Factory Settings
Press Select to reset to factory settings. Press Accept to confirm or Cancel to exit
without restoring the factory settings.
6.5. REAGENTS & ACCESSORIES
Press the key to enter the menu. Use the functional keys to select
Reagents / Accessories and press Select to access a list of reagents and accessories.
To exit press the key.

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GENERAL OPERATIONS
6.6. CONTEXTUAL HELP
The HI97725 offers an interactive contextual help mode that assists the user at any
time. To access the help screen press the key.
The instrument will display additional information related to the current screen. To read
all the available information, scroll the text using the functional keys.
To exit help mode press the or the key and the meter will return to the
previous screen.
6.7. BATTERY MANAGEMENT
The meter will perform an auto-diagnostic test when it is powered on. During this test,
the Hanna Instruments®logo will appear on the LCD. If the auto-diagnostic test was
successful, the meter is ready for use. The battery icon on the LCD will indicate the
battery status:
• battery full
• battery below 10%, replace the batteries soon
• battery is low, replace the batteries with new ones
To conserve battery, the meter will turn off automatically after 15 minutes of
inactivity. If a zero reading has been done but not a read, auto-off time is increased
to 30 minutes.

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PHOTOMETER
7. PHOTOMETER
7.1. METHOD SELECTION
Press Methods when in measurement mode to access the list of methods. Use the
functional keys to highlight the desired method then press Select.
The selected method will be saved when the instrument is powered off.
7.2. COLLECTING & MEASURING SAMPLES AND REAGENTS
Proper Use of Powder Packet
1. Use scissors to open the powder packet.
2. Push the edges of the packet to form a spout.
3. Pour out the content of the packet.
Proper Use of Dropper Bottle
1. Tap the dropper on the table several times and wipe the outside of the tip with
a cloth.
2. Always keep the dropper bottle in a vertical position while dosing the reagent.

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PHOTOMETER
7.3. CUVETTE PREPARATION
Proper mixing is very important for reproducibility of the measurements. The proper
mixing technique is listed in the method procedure.
(a) The mixing method is indicated with “shake gently“using one of the following icons:
(b) The mixing method is indicated with “swirl“ using one of the following icons:
In order to avoid reagent leaking and to obtain more accurate
measurements, close the cuvette first with the supplied HDPE
plastic stopper and then the black cap.
Whenever the cuvette is placed into the measurement holder,
it must be dry outside and free of fingerprints, oil or dirt. Wipe it
thoroughly with HI731318 microfiber cleaning cloth or a lint-free
wipe 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
has been added. For best accuracy, respect the timings
described in the method.
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
when possible.
Discard the sample immediately after the reading has been taken, or the glass might
become permanently stained.
All the reaction times reported in this manual are at 25 °C (77 °F). In general, the
reaction time should be increased for temperatures lower than 20 °C (68 °F), and
decreased for temperatures higher than 25 °C (77 °F).

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METHOD PROCEDURE
8. METHOD PROCEDURE
8.1. FREE CHLORINE (POWDER REAGENT)
Note: Free and Total Chlorine have to be measured separately with fresh unreacted
samples, following the related procedures, if both values are desired.
REQUIRED REAGENTS
Code Description Quantity
HI93701-0 Free Chlorine Reagent 1 packet
REAGENT SETS
HI93701-01 Free Chlorine Reagent - 100 tests
HI93701-03 Free Chlorine Reagent - 300 tests
For other accessories see ACCESSORIES section.
MEASUREMENT PROCEDURE
• Select the Free Chlorine (Powder) method using the procedure described in the
METHOD SELECTION section.
Note: If tutorial mode is disabled, follow the measurement procedure below. If the
tutorial mode is enabled, press Measure and follow the messages on the screen.
• Fill the cuvette with 10 mL of unreacted sample (up
to the mark). Replace the plastic stopper and the cap.
• Insert the cuvette into the holder and ensure that the
notch on the cap is positioned securely in the groove.
• Press Zero. The display will show “-0.0-” when the meter is zeroed and ready for
measurement.
10 mL