Hanna Instruments pH 21 User manual

pH20 • pH21
Basic pH meters
Instruction Manual
www.hannainst.com

32
pH 20 and pH 21 are basic pH meters designed for simplicity of use in
all applications where rapid daily controls are required.
These meters are also suitable for educational field, where students begin
to approach pH measurements.
Both models measure pH in the 0 to 14 range, with 0.01 resolution.
In addition, pH 21 can also measure ORP (mV) by using a proper ORP
electrode (optional).
The pH calibration procedure is automatic and can be performed at
1 or 2 points.
Readings can be manually (MTC) or automatically (ATC) compensated
for temperature variations.
The automatic temperature compensation is performed if using the
optional HI 7662 temperature probe, while for manual compensation
the user can set the temperature value through the arrow keys.
The meters are also provided with the Hold function, which allows to
freeze reading on the LCD by simply pressing the HOLD button.
GENERAL DESCRIPTION
PRELIMINARY EXAMINATION
Remove the instrument from the packing material and examine it to
make sure that no damage has occurred during shipping. If there is
any damage, notify your Dealer.
Each meter is supplied complete with:
• HI 1110B pH electrode with BNC connector and 1 m cable
• 12 Vdc adapter
• instruction manual
Note: Save all packing material until you are sure that the instru-
ment functions correctly. All defective items must be returned in
the original packing with the supplied accessories.
Dear Customer,
Thank you for choosing a Hanna Instruments Product.
Please read this instruction manual carefully before using the instru-
ment. This manual will provide you with all the necessary information
for the correct use of the instrument, as well as a precise idea of its
versatility in a wide range of applications.
If you need additional technical information, do not hesitate to e-mail
us at [email protected]
These instruments are in compliance with the directives.
TABLE OF CONTENTS
GENERAL DESCRIPTION ........................................................................... 3
PRELIMINARY EXAMINATION ...................................................................... 3
FUNCTIONAL DESCRIPTION ........................................................................ 4
SPECIFICATIONS ................................................................................... 5
OPERATIONAL GUIDE ................................................................................ 6
pH CALIBRATION ................................................................................... 9
ELECTRODE CONDITIONING AND MAINTENANCE ........................................ 11
ACCESSORIES ................................................................................. 13
Hanna Instruments reserves the right to modify the design, construction and
appearance of its products without advance notice.
WARRANTY
All Hanna Instruments meters are warranted for two years
against defects in workmanship and materials when used for their
intended purpose and maintained according to instructions. The
electrodes and the probes are warranted for six months. This
warranty is limited to repair or replacement free of charge. Damages
due to accident, misuse, tampering or lack of prescribed mainte-
nance are not covered. If service is required, contact the dealer from
whom you purchased the instrument. If under warranty, report the
model number, date of purchase, serial number and the nature of
the failure. If the repair is not covered by the warranty, you will be
notified of the charges incurred. If the instrument is to be returned
to Hanna Instruments, first obtain a Returned Goods Authorization
number from the Customer Service department and then send it
with shipping costs prepaid. When shipping any instrument, make
sure it is properly packaged for complete protection.

54
SPECIFICATIONS
FUNCTIONAL DESCRIPTION
1. Liquid Crystal Display
2. CAL key, to enter and exit the calibration mode
3. CFM key, to confirm calibration values
4. ↑↑
↑↑
↑°C and ↓↓
↓↓
↓°C keys, to manually set temperature value for
compensation
5. HOLD key, to freeze reading on display
6. RANGE key, to select measurement range
7. ON/OFF key, to turn the meter on and off
+-
Note: These instruments use the following configuration.
It is recommended to use the Hanna HI 710005 or HI 710006
voltage adapters (supplied with the meter) which are provided with
the proper polarity configuration.
The meters can also be powered with other adapters. In this case,
remember to check the correct polarity of the adapter before connect-
ing it to the meter.
REAR PANEL
1. BNC connector for pH or ORP (pH 21 only) electrode.
2. Temperature probe socket for use with the HI 7662.
3. Power supply input. Plug the 12 Vdc adapter into the DC socket,
then into the mains.
Notes:
• Make sure the mains line is protected by a fuse.
• If the instrument needs to be unplugged, press the ON/OFF
key before disconnecting it from the mains.
Range pH 0.00 to 14.00
ORP ±1999 mV (pH 21 only)
°C 0.0 to 100.0
Resolution pH 0.01
ORP 1 mV (pH 21 only)
°C 0.1
Accuracy pH ±0.02
(@20°C/68°F) ORP ±2 mV (pH 21 only)
°C ±1
pH Calibration Automatic, 1 or 2 point
Temperature Automatic (with temperature probe) or
Compensation manual (adjustable with arrow keys)
pH Electrode HI 1110B combination pH electrode
with BNC and 1 m cable (included)
Temperature probe HI 7662 (optional)
Power supply 12 Vdc adapter (included)
Environment 0 to 50°C (32 to 122°F)
RH max 95% non-condensing
Dimensions 230 x 170 x 75 mm (9.1x6.7x 3")
Weight 500 g (1.1 lb.)

76
Note: If measurements are taken in different samples successively, it is
recommended to clean the electrode thoroughly to avoid cross-
contamination. After cleaning, rinse the electrode with water
and then with some of the solution to be tested.
MANUAL TEMPERATURE COMPENSATION
• When the temperature probe is not connected, the default
temperature value is 25°C.
• To temperature compensate the pH read-
ing, measure the temperature of the solution
with a ChecktempC or another accurate
thermometer. E.g. 20°C.
• Press the RANGE key to enter the °C mode and adjust the
displayed value by using the arrow keys.
TAKING ORP MEASUREMENTS (for pH21 only)
•The meter is factory calibrated for ORP (mV) range. Please
contact the nearest Hanna Service Center for recalibration,
if needed.
• Connect an ORP electrode (optional, see "Accessories" section) to the
BNC connector on the rear panel (see page 4).
• Connect the 12VDC power adapter to the instrument (see page 4)
and then to the mains.
• Press the ON/OFF key to turn the meter
on.
• Press the RANGE key to select the ORP
(mV) mode.
• Remove the electrode protective cap, then immerse the ORP
electrode in the sample to be tested.
Note: The electrode should be submerged approximately 4 cm (1½")
into the solution.
Note: With refillable electrodes, to obtain a faster response unscrew
the refill hole cap during measurements.
• Shake briefly and wait a few seconds for
the reading to stabilize, i.e. when the
hourglass symbol stops blinking. The LCD
will show the ORP (mV) value.
TAKING pH MEASUREMENTS
• Make sure that the instrument has been calibrated for pH before
taking measurements (see "pH Calibration" section for details).
• Connect the supplied HI 1110B pH electrode to the BNC connec-
tor on the rear panel (see page 4).
• If automatic temperature compensation is required, connect the
HI 7662 temperature probe (optional) to the proper socket on
the rear panel (see page 4).
• Connect the 12VDC power adapter to the instrument (see page 4)
and then to the mains.
• Press the ON/OFF key to turn the meter
on.
• Press the RANGE key to select the pH
mode, if necessary.
• Remove the electrode protective cap, then immerse the pH
electrode and the temperature probe in the sample to be tested.
Note: If the pH electrode is dry, immerse it in HI 70300 storage
solution for at least one hour to reactivate it.
Note: The pH electrode should be submerged
approximately 4 cm (1½") into the
solution and the temperature probe (if
used) should be located as close as
possible to the electrode.
Note: With refillable electrodes, to obtain a faster response unscrew
the refill hole cap during measurements.
• Shake briefly and wait a few seconds for
the reading to stabilize, i.e. when the
hourglass symbol stops blinking. The LCD
will show the pH value automatically com-
pensated for temperature variations.
• After measurements, turn the meter off by pressing the ON/OFF
key, disconnect the power adapter from the mains and the pH
electrode from the instrument.
• Store the electrode with a few drops of HI 70300 solution in the
protective cap.
NEVER USE DISTILLED OR DEIONIZED WATER FOR STORING
PURPOSES.
OPERATIONAL GUIDE

98
pH CALIBRATION
For better accuracy the instruments should be calibrated frequently,
and however:
1. After electrode replacement.
2. After testing aggressive chemicals.
3. At least once a month.
4. When extreme accuracy is required.
• Turn the instrument on after connecting the pH electrode and the
temperature probe.
• Immerse the temperature probe together with the electrode into
pH 7.01 buffer solution or manually set the temperature (see the
note here below).
Note: The pH electrode should be submerged approximately 4 cm
(1½") into the solution and the temperature probe should be
located as close as possible to the electrode.
Note: If the temperature probe is not used, measure the buffer value
with a thermometer, enter the °C mode by pressing the RANGE
key and adjust the displayed value by using the arrow keys.
• Press the RANGE key to display pH readings.
•Press the CAL key to enter the calibration mode: the display
flashes "pH 7.01" and the hourglass symbol lights up.
• Wait till the hourglass symbol on the LCD turns off and the "pH"
tag stops blinking, then press CFM to confirm the first calibration
point (offset). "pH 4.01" will flash on the LCD.
• If a single point calibration at pH 7.01 is desired, press the CAL
key to exit, otherwise proceed with the second point.
• Rinse and immerse both pH electrode and temperature probe (if
used) in pH 4.01 or pH 10.01 buffer solution. The meter
automatically recognizes the buffer and displays the correct value.
• After measurements, turn the meter off by pressing the ON/OFF
key, disconnect the power adapter from the mains and the
electrode from the instrument.
Note: To perform correct ORP measurements, the surface of the ORP
electrode must be clean and smooth.
Note: When not in use, the tip of the electrode should be kept moist
and safe from any mechanical stress which might cause
damage to the glass/platinum junction.
TAKING TEMPERATURE MEASUREMENTS
•The meter is factory calibrated for temperature range.
Please contact the nearest Hanna Service Center for
recalibration, if needed.
• Connect the HI 7662 temperature probe (optional) to the proper
connector on the rear panel (see page 4).
• Connect the 12VDC power adapter to the instrument (see page 4)
and then to the mains.
• Press the ON/OFF key to turn the meter
on.
• Press the RANGE key to select the tem-
perature (°C) mode.
• Immerse the probe in the sample to be tested.
• Shake briefly and wait a few seconds for
the reading to stabilize, i.e. when the
hourglass symbol stops blinking. The LCD
will show the temperature (°C) value.
• After measurements, turn the meter off by pressing the ON/OFF
key, disconnect the power adapter from the mains and the probe
from the instrument.
HOLD FUNCTION
• To freeze a reading on display, from measurement mode press
and hold the HOLD key. The "HOLD" tag will light up.
• The meter returns to normal mode when the HOLD key is released.
Note: The RANGE key is not working while in HOLD mode.

1110
ELECTRODE CONDITIONING & MAINTENANCE
PREPARATION
Remove the electrode protective cap.
DO NOT BE ALARMED IF ANY SALT DEPOSITS ARE PRESENT: this is
normal with electrodes and they will disappear when rinsed with
water.
During transport tiny bubbles of air may have formed inside the glass
bulb. The electrode cannot function properly under these conditions.
These bubbles can be removed by "shaking down" the electrode as
you would do with a glass thermometer.
If the bulb and/or junction are dry, soak the electrode in HI 70300
Storage Solution for at least one hour.
For refillable electrodes, if the refill solution (electrolyte) is more than
2½ cm (1") below the fill hole, add the appropriate Electrolyte
Solution.
MEASUREMENT
Rinse the electrode tip with distilled water, immerse it (4 cm / 1½")
in the sample and stir gently for a few seconds.
For a faster response and to avoid cross contamination of the samples,
rinse the electrode tip with the solution to be tested, before taking
any measurements.
STORAGE
To minimize clogging and ensure a quick response time, the glass
bulb and the junction should always be kept moist.
When not in use, store it with a few drops of HI 70300 storage
solution or HI 7007 pH 7.01 buffer in the protective cap.
NEVER STORE THE ELECTRODE IN DISTILLED OR DEIONIZED
WATER.
PERIODIC MAINTENANCE
Inspect electrode and cable. The cable used for the connection to the
meter must be intact and there must be no points of broken
insulation on the cable or cracks on the electrode stem or bulb. If any
scratches or cracks are present, replace the electrode. Rinse off any salt
deposits with water.
Connectors must be perfectly clean and dry.
Refill the electrode with fresh electrolyte (see the electrode’s specifica-
tions to select the correct refilling solution). Allow the electrode to
stand upright for 1 hour. Follow the Storage Procedure.
• Wait till the hourglass symbol on the LCD turns off and the "pH"
tag stops blinking, then press CFM to confirm the second calibra-
tion point (slope).
• The meter automatically returns to normal measurement mode.
Note: To abort a calibration procedure and save previous calibration
data, press the CAL key while the "pH" tag is still blinking.
Recommendations for Users
Before using these products, make sure that they are entirely suitable for the environ-
ment in which they are used.
Operation of these instruments in residential area could cause unacceptable inter-
ferences to radio and TV equipments, requiring the operator to take all necessary
steps to correct interferences.
The glass bulb at the end of the electrode is sensitive to electrostatic discharges.
Avoid touching this glass bulb at all times.
During operation, ESD wrist straps should be worn to avoid possible damage to the
electrode by electrostatic discharges.
Any variation introduced by the user to the supplied equipment may degrade the
instrument's EMC performance.
To avoid electrical shock, do not use these instruments when voltages at the measure-
ment surface exceed 24VAC or 60VDC.
To avoid damages or burns, do not perform any measurement in microwave ovens.

1312
ACCESSORIES
pH CALIBRATION SOLUTIONS
HI 70004P pH 4.01 buffer solution, 20 mL sachet, 25 pcs
HI 7004M pH 4.01 buffer solution, 230 mL bottle
HI 7004L pH 4.01 buffer solution, 500 mL bottle
HI 8004L pH 4.01 buffer solution, 500 mL FDA bottle
HI 70007P pH 7.01 buffer solution, 20 mL sachet, 25 pcs
HI 7007M pH 7.01 buffer solution, 230 mL bottle
HI 7007L pH 7.01 buffer solution, 500 mL bottle
HI 8007L pH 7.01 buffer solution, 500 mL FDA bottle
HI 70010P pH 10.01 buffer solution, 20 mL sachet, 25 pcs
HI 7010M pH 10.01 buffer solution, 230 mL bottle
HI 7010L pH 10.01 buffer solution, 500 mL bottle
HI 8010L pH 10.01 buffer solution, 500 mL FDA bottle
STORAGE & CLEANING SOLUTIONS
HI 70300M Storage solution, 230 mL bottle
HI 80300M Storage solution, 230 mL FDA bottle
HI 70300L Storage solution, 500 mL bottle
HI 80300L Storage solution, 500 mL FDA bottle
HI 70000P Electrode rinsing solution, 20 mL sachet, 25 pcs
HI 7061M General cleaning solution, 230 mL bottle
HI 8061M General cleaning solution, 230 mL FDA bottle
HI 7061L General cleaning solution, 500 mL bottle
HI 8061L General cleaning solution, 500 mL FDA bottle
HI 7073M Protein cleaning solution, 230 mL bottle
HI 8073M Protein cleaning solution, 230 mL FDA bottle
HI 7073L Protein cleaning solution, 500 mL bottle
HI 8073L Protein cleaning solution, 230 mL FDA bottle
HI 7074M Inorganic cleaning solution, 230 mL bottle
HI 7074L Inorganic cleaning solution, 500 mL bottle
HI 7077M Oil & Fat cleaning solution, 230 mL bottle
HI 8077M Oil & Fat cleaning solution, 230 mL FDA bottle
HI 7077L Oil & Fat cleaning solution, 500 mL bottle
HI 8077L Oil & Fat cleaning solution, 500 mL FDA bottle
REFILLING ELECTROLYTE SOLUTIONS
HI 7071 3.5M KCl + AgCl electrolyte, 4 x 30 mL, for single
junction electrodes
HI 8071 3.5M KCl + AgCl electrolyte, 4 x 30 mL, for single
junction electrodes (FDA approved bottle)
HI 7072 1M KNO3electrolyte, 4 x 30 mL
CLEANING PROCEDURE
General : Soak in HI 7061 General Cleaning Solution for about 30
minutes.
Removal of films, dirt or deposits on the membrane/junction:
Protein : Soak in HI7073 Protein Cleaning Solution for 15 minutes.
Inorganic : Soak in HI 7074 Inorganic Cleaning Solution for 15
minutes.
Oil/grease : Soak in HI 7077 Oil & Fat Cleaning Solution for 1
minute.
IMPORTANT: After performing any of the cleaning procedures, rinse
the electrode thoroughly with distilled water and soak it in HI70300
Storage Solution for at least 1 hour before taking measurements.
TROUBLESHOOTING
Evaluate the electrode performance based on the following.
•Noise (Readings fluctuate up and down) could be due to:
- Clogged/Dirty Junction: refer to the Cleaning Procedure.
- Loss of shielding due to low electrolyte level: refill with
proper solution.
•Dry Membrane/Junction: soak in HI70300 Storage Solution for
at least 1 hour.
•Drifting: soak the electrode tip in warm HI7082 Solution for one
hour and rinse the tip with distilled water (refill with fresh
electrolyte if necessary).
•Low Slope: refer to the Cleaning Procedure.
•No Slope: - Check the electrode for cracks in glass stem or bulb
(replace the electrode if cracks are found).
- Make sure cable and connections are not dam-
aged nor lying in a pool of water or solution.
•Slow Response/Excessive Drift: soak the tip in HI7061 Solu-
tion for 30 min, rinse thoroughly in distilled water and then
follow the Cleaning Procedure.
•For ORP Electrodes: polish the metal tip with a lightly abrasive
paper while paying attention not to scratch the surface, then
wash it thoroughly with water.
Note: For field applications, it is always recommended to keep a
conditioned spare electrode handy. When anomalies can not
be resolved with a simple maintenance, change the electrode
and recalibrate the meter.

HI 2031B Glass body, semimicro, conic tip, refillable, combina-
tion. Use: semisolid products.
FC 100B PVDF body, double junction, refillable, combination.
Use: general purpose for food industry.
FC 200B PVDF body, open junction, conic shape, Viscolene, non-
refillable, combination. Use: meat, cheese.
FC 210B Glass body, double junction, conic shape, Viscolene,
non-refillable, combination. Use: milk, yogurt.
FC 220B Glass body, triple ceramic junction, refillable, combina-
tion. Use: food processing.
ORP ELECTRODES
All electrode part numbers ending with B are supplied with BNC
connector and 1 m (3.3') cable.
HI 3131B Glass body, refillable, combination, platinum sensor.
Use: titration.
HI 3230B Plastic body, gel-filled, combination, platinum sensor.
Use: general purpose.
HI 4430B Plastic body, gel-filled, combination gold sensor.
Use: general purpose.
For a complete list of available pH and ORP electrodes, consult the
Hanna General Catalog or visit www.hannainst.com
OTHER ACCESSORIES
ChecktempC Pocket-size thermometer (range -50.0 to 150.0°C)
HI 710005 115 Vac/12 Vdc power adapter, US plug
HI 710006 230 Vac/12 Vdc power adapter, European plug
HI 76405 Electrode holder
HI 7662 Temperature probe with 1 m (3.3') cable
HI 8427 pH/ORP electrode simulator with 1 m (3.3') coaxial
cable and BNC connector
HI 931001 pH/ORP electrode simulator with LCD, 1 m (3.3')
coaxial cable and BNC connector
HI 8072 1M KNO3electrolyte, 4 x 30 mL (FDA approved bottle)
HI 7082 3.5M KCl electrolyte, 4 x 30 mL, for double junction
electrodes
HI 8082 3.5M KCl electrolyte, 4 x 30 mL, for double junction
electrodes (FDA approved bottle)
ORP SOLUTIONS
HI 7091M Reducing pretreatment solution, 230 mL bottle
HI 7091L Reducing pretreatment solution, 500 mL bottle
HI 7092M Oxidizing pretreatment solution, 230 mL bottle
HI 7092L Oxidizing pretreatment solution, 500 mL bottle
HI 7020M Test solution, 200-275 mV, 230 mL bottle
HI 7020L Test solution, 200-275 mV, 500 mL bottle
HI 7021M Test solution, 240 mV, 230 mL bottle
HI 7021L Test solution, 240 mV, 500 mL bottle
HI 7022M Test solution, 470 mV, 230 mL bottle
HI 7022L Test solution, 470 mV, 500 mL bottle
pH ELECTRODES
All electrode part numbers ending with B are supplied with BNC
connector and 1 m (3.3') cable.
HI 1043B Glass body, double junction, refillable, combination.
Use: strong acid/alkali.
HI 1048B Glass body, annular open junction, refillable, combina-
tion. Use: wine processing.
HI 1053B Glass body, triple ceramic junction, conic shape, refill-
able, combination. Use: emulsions.
HI 1083B Glass body, micro, Viscolene, non-refillable, combina-
tion. Use: biotechnology, micro titration.
HI 1110B Glass body, single junction, gel-filled, combination.
Use: general purpose.
HI 1131B Glass body, single junction, refillable, combination.
Use: general purpose.
HI 1230B Plastic body, double junction, gel-filled, combination.
Use: general, field.
HI 1330B Glass body, semimicro, single junction, refillable, com-
bination. Use: laboratory, vials.
HI 1331B Glass body, semimicro, single junction, refillable, com-
bination. Use: flasks.
HI 1332B Plastic body, double junction, refillable, combination.
Use: general purpose.
HI 1413B Glass body, single junction, flat tip, Viscolene, non-
refillable, combination. Use: surface measurement.

MANPH21R1 07/05
SALES AND TECHNICAL SERVICE CONTACTS
Australia:
Tel. [phone] • Fax [phone]
China:
Tel. [phone] • Fax [phone]
Egypt:
Tel. & Fax [phone]
Germany:
Tel. [phone] • Fax [phone]
Greece:
Tel. [phone] • Fax [phone]
Indonesia:
Tel. [phone] • Fax [phone]
Japan:
Tel. [phone] • Fax [phone]
Korea:
Tel. [phone] • Fax [phone]
Malaysia:
Tel. [phone] • Fax [phone]
Singapore:
Tel. [phone] • Fax [phone]
South Africa:
Tel. [phone] • Fax [phone]
Taiwan:
Tel. [phone] • Fax [phone]
Thailand:
Tel. [phone] • Fax [phone]
United Kingdom:
Tel. [phone] • Fax [phone]
USA:
Tel. [phone] • Fax [phone]
For e-mail contacts and complete list of Sales and
Technical offices, please see www.hannainst.com