Hanna Instruments HI 22091, HI 2209 Instruction Manual

Instruction Manual

HI 2209 • HI 22091

Bench pH Meters

www.hannainst.comPrinted in ROMANIA

MAN2209 07/14

Hanna Instruments Inc.

Highland Industrial Park
584 Park East Drive
Woonsocket, RI 02895 USA

Technical Support for Customers

Tel. [phone]
Fax [phone]
E-mail [e-mail]
www.hannainst.com

Local Sales and Customer Service Office

Dear Customer,
Thank you for choosing a Hanna Instruments Product.

Please read this instruction manual carefully before using these
instruments. This manual will provide you with the necessary information
for the correct use of these instruments, as well as a precise idea of
their versatility.
If you need additional technical information, do not hesitate to e-mail
us at [e-mail] or view our worldwide contact list at
www.hannainst.com.

WARRANTY ................................................................................. 2

PRELIMINARY EXAMINATION ....................................................... 3

GENERAL DESCRIPTION ............................................................... 3

FUNCTIONAL DESCRIPTION ......................................................... 4

SPECIFICATIONS.......................................................................... 5

OPERATIONAL GUIDE .................................................................. 6

pH CALIBRATION ........................................................................ 8

pH BUFFER TEMPERATURE DEPENDENCE ..................................... 10

ELECTRODE CONDITIONING AND MAINTENANCE .......................... 11

TEMPERATURE CORRELATION FOR pH SENSITIVE GLASS ............ 14

ACCESSORIES ............................................................................ 15

ELECTRODE APPLICATION REFERENCE GUIDE ............................... 21

TABLE OF CONTENTS

HI 2209 and HI 22091 are guaranteed for two years against defects
in workmanship and materials when used for their intended purpose
and maintained according to instructions. Electrodes and probes are
guaranteed for six months. This warranty is limited to repair or
replacement free of charge.
Damage due to accident, misuse, tampering or lack of prescribed
maintenance 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 problem. 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 Technical
Service department and then send it with shipping costs prepaid.
When shipping any instrument, make sure it is properly packed for
complete protection.

WARRANTY

RECOMMENDATIONS FOR USERS

Before using these products, make sure that they are entirely suitable for
the environment in which they are used.

Operation of these instruments in residential area could cause
unacceptable interferences to radio and TV equipment, requiring the
operator to follow all necessary steps to correct interferences.

The glass bulb at the end of the pH electrode is sensitive to
electrostatic discharges. Avoid touching this glass bulb at all times.
During calibration, ESD wrist straps should be worn to avoid possible
damage to the electrode by electrostatic discharge.

To maintain the EMC performance of this equipment, the recommended
cables noted in the user's manual must be used. 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 measurement surface exceed 24 Vac or 60 Vdc.

To avoid damage or burns, do not perform any measurement in microwave
ovens.

All rights are reserved. Reproduction in whole or in part is prohibited
without the written consent of the copyright owner.

Hanna Instruments reserves the right to modify the design, construction

or appearance of its products without advance notice.

3

HI 2209 bench pH meter is designed for simplicity of use.
It features a large easy-to-read liquid crystal display (LCD)
and user friendly keyboard.
The pH calibration is made simple through the easy-to-operate
front panel knobs for offset and slope adjustment.
A front knob is provided for easy manual set for temperature
compensation of the pH reading.
HI 2209 can also measure ORP (Oxidation Reduction Potential)
in the mV range.
The range selection (pH, mV or °C for temperature compensation)
is made simple through the front membrane keyboard.
It is also available the model HI 22091 with recorder output
feature.

GENERAL DESCRIPTION

PRELIMINARY EXAMINATION

Remove the instrument from the packing material and examine
it carefully to make sure that no damage has occurred during
shipping. If there is any damage, notify your dealer.

Each meter is supplied complete with:

• HI 1332B plastic-body combination double-junction
refillable pH electrode with BNC connector and 1 m
(3.3') cable

• 12 Vdc adapter

• Instruction manual.

Note:Save all packing material until you are sure that the

instrument functions correctly. All defective items must
be returned in the original packing with the supplied
accessories.

22

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4

FUNCTIONAL DESCRIPTION

1) Liquid Crystal Display (LCD)

2) Temperature setting knob

3) °C range selection key

4) mV range selection key

5) pH range selection key

6) pH offset adjustment knob

7) pH slope adjustment knob

8) Sample holders

9) Analog output connectors (HI 22091 only)

10) BNC electrode connector

11) Reference electrode socket

12) Power adapter socket

13) ON/OFF switch

Front Panel

Rear Panel

21

ELECTRODE APPLICATION

REFERENCE GUIDE

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5

SPECIFICATIONS

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20

EXTENSION CABLES FOR SCREW-TYPE ELECTRODES
(SCREW TO BNC ADAPTER)

HI 7855/1 Extension cable 1m (3.3') long
HI 7855/3 Extension cable 3m (9.9') long
HI 7855/5 Extension cable 5m (16.5') long
HI 7855/10 Extension cable 10m (33') long

HI 7855/15 Extension cable 15m (49.5') long

OTHER ACCESSORIES

HI 710005 Voltage adapter from 115 Vac to 12 Vdc
HI 710006 Voltage adapter from 230 Vac to 12 Vdc
ChecktempC Pocket-size thermometer (range -50.0 to 150.0°C)
HI 76405 Electrode holder

HI 8427 pH and ORP electrode simulator with 1 m (3.3')

coaxial cable ending in female BNC connectors

HI 931001 pH and ORP electrode simulator with LCD and 1 m

(3.3') coaxial cable ending in female BNC connectors

CONNECT TO
SCREW TYPE
ELECTRODES

CONNECT TO THE

BNC SOCKET

OF THE METER

HI 7855 SERIES CABLE CONNECTORS

CONNECTOR AND 3.0 mm (0.12") CABLE WITH BNC

6

4 cm

(1½")

POWER CONNECTION

Plug the supplied 12 Vdc adapter into the power supply socket
(#12 on page 4).

Note: Make sure the mains line is protected by a fuse.

ELECTRODE CONNECTION

For combination pH or ORP electrodes (with internal reference)
connect the electrode's BNC to the socket provided (#10 on
page 4).

For an electrode with a separate reference, connect the measuring
electrode's BNC to the BNC socket (#10 on page 4) and the
reference electrode's jack to the socket provided (#11 on
page 4).

Note: To prevent damage to the electrode, remove the pH

electrode from the solution before turning the meter off.
If the meter is OFF, detach the electrode from the meter
before immersing the electrode in the storage solution.

TAKING pH MEASUREMENTS

Make sure that the instrument has been calibrated for pH
before taking pH measurements.

• Put the beakers (bottles 50 or 100 mL) with the
solutions under test on the sample holders.

• Switch the instrument on by pressing the ON/OFF
switch.

• Press the pH key to display the pH measurement.

• Immerse the electrode tip (4 cm / 1½") into the
sample and shake briefly.

• Take the temperature of the solution with a

ChecktempC

or a glass thermometer (e.g.25°C).

• Press and hold the Temp key to display temperature
setting on the LCD and adjust the temperature
knob to display the temperature of the sample.

OPERATIONAL GUIDE

19

HI 1413B

Glass-body, single junction, flat tip, Viscolene, non-refillable, combination
pH electrode. Use: surface measurement.

ORP ELECTRODES

HI 3131B

Glass-body, refillable, combination platinum ORP electrode.
Use: titration.

HI 3230B

Plastic-body (PES), gel-filled, combination platinum ORP electrode.
Use: general purpose.

HI 4430B

Plastic-body (PES), gel-filled, combination gold ORP electrode. Use:
general purpose.

110 mm

4.3"

12 mm

0.5"

HI 1413

150 mm

5.9"

12 mm

0.5"

"S" VERSION

HI 3131

120 mm

4.7"

12 mm

0.5"

HI 3230

"S" VERSION

120 mm

4.7"

12 mm

0.5"

HI 4430

"S" VERSION

7

• Release Temp key. The meter returns to pH range.

• The display shows the pH value of the test solution
compensated for temperature.

If measurements are taken in different samples successively, it
is recommended that the electrode be rinsed thoroughly for
better conditioning and to eliminate cross-contamination of
the sample.

For the rinsing process, it is recommended to use a liberal
amount of the next solution to be measured.

TAKING ORP MEASUREMENTS

HI 2209 and HI 22091 have the capability to take ORP
measurements, using an ORP electrode. Hanna Instruments
offers a variety of ORP electrodes for this purpose (see
accessories). Contact your Dealer for more information.

• Connect the ORP electrode to the meter and
submerge the tip (4 cm / 1½") into the
sample to be tested.

Note:ORP measurements are taken without temperature

compensation.

• Press the mV key to enter the mV mode. Allow
a few minutes for the reading to stabilize.

• The display will indicate the mV value (positive or negative).

AFTER MEASUREMENTS

• Press the ON/OFF switch to switch the instrument off.

4 cm

(1½")

18

FC 100B

Plastic-body (PVDF), double junction, refillable, combination pH electrode.
Use: general purpose for food industry.

FC 200B

Plastic-body (PVDF), open junction, conic, Viscolene, non-refillable,
combination pH electrode. Use: meat & cheese.

FC 210B

Glass-body, double junction, conic, Viscolene, non-refillable, combina­tion pH electrode. Use: milk, yogurt.

FC 220B

Glass-body, triple-ceramic, single junction, refillable, combination pH
electrode. Use: food processing.

FC 911B

Plastic-body (PVDF), double junction, refillable with built-in amplifier,
combination pH electrode. Use: very high humidity.

120 mm

4.7"

12 mm

0.5"

FC 100

75 mm

2.95"

6 mm

0.25"

FC 200

120 mm

4.7"

12 mm

0.5"

FC 210

120 mm

4.7"

12 mm

0.5"

9.5mm DIA

0.37"

FC 220

110 mm

4.3"

12 mm

0.5"

FC 911

8

HI 7004 HI 7007

HI 7004

IMPORTANT

The instrument's pH range should be re-calibrated:

• When the meter is new.

• Whenever the pH electrode is replaced.

• At least once a month.

• After use in aggressive chemicals.

• After cleaning procedure and changing the reference electrolyte.

• For greatest accuracy.

PREPARATION

Pour small quantities (up to 4 cm / 1½"
level) of pH 7.01 (HI 7007) and pH

4.01 (HI 7004) or pH 10.01 (HI 7010)
solution into clean beakers (or 100 mL
bottles). If possible use plastic beakers to minimize any EMC
interferences.
If you are measuring in the acid range, use pH 4.01 as second
buffer; if you are measuring in
the alkaline range, use pH 10.01
as second buffer.
For accurate calibration, use two
beakers for each buffer solution; the first for rinsing the
electrode, the second for calibration. In this way, contamination
of the buffer is minimized.

Note: The electrode should be submerged approximately 4 cm

(1½") into the solution.

Note: If you need to calibrate to NBS standards, use pH 6.86

(HI 7006) and pH 9.18 (HI 7009) instead of pH 7.01
and 10.01 respectively.

Use a

ChecktempC

or a glass thermometer as reference.
Put the beakers with the calibrations solutions on the beaker
holders on the top of the instrument.

PROCEDURE

• Switch the instrument on by pressing the

ON/OFF switch.

pH CALIBRATION

HI 7007

RINSE

HI 7007

CALIBRATION

17

HI 1330B

Glass-body, semimicro, single junction, refillable, combination pH
electrode. Use: laboratory, vials.

HI 1331B

Glass-body, semimicro, single junction, refillable, combination pH
electrode. Use: flasks.

HI 1230B

Plastic-body (Ultem®), double junction, gel-filled, combination pH
electrode. Use: general, field.

HI 2031B

Glass-body, semimicro, conic, refillable, combination pH electrode. Use:
semisolid products.

HI 1332B

Plastic-body (Ultem®), double junction, refillable, combination pH
electrode. Use: general purpose.

120 mm

4.7"

5mm

0.2"

5mm DIA

0.2"

"S" VERSION

HI 1330

120 mm

4.7"

12 mm

0.5"

HI 1230

75 mm

2.95"

6 mm

0.25"

HI 2031

120 mm

4.7"

12 mm

0.5"

"S" VERSION

HI 1332

210 mm

8.25"

8 mm

0.3"

7.5mm DIA

0.29"

"S" VERSION

HI 1331

9

4 cm

(1½")

• Rinse and immerse the pH electrode into pH

7.01 buffer and shake briefly. Wait for the
reading to stabilize.

• Note the temperature of the buffer solution
using a

ChecktempC

or a glass thermometer

(e.g. 20°C).

• Press and hold the Temp key to select
temperature setting.

• Adjust the Temperature knob until the LCD shows the
noted temperature.

• Release the Temp key. The instruments returns to pH
range.

• Wait a couple of minutes and adjust the Offset knob until
display shows the pH value at the noted temperature (see
the pH versus temperature chart).

• Rinse and immerse the pH electrode in pH 4.01 /pH 10.01
buffer and shake briefly.

• Wait a couple of minutes and adjust the Slope knob until
display shows the pH value at the noted temperature (see
the pH versus temperature chart).

• The pH calibration is now complete.

16

ORP PRETREATMENT SOLUTIONS

HI 7091L Reducing pretreatment solution, 500 mL
HI 7092L Oxidizing pretreatment solution, 500 mL

pH ELECTRODES

All electrodes part numbers ending in B are supplied with a BNC
connector and 1 m (3.3') cable.

HI 1043B

Glass-body, double junction, refillable, combination pH electrode. Use:
strong acid/alkali.

HI 1053B

Glass-body, triple ceramic, conic shape, refillable, combination pH
electrode. Use: emulsions.

HI 1083B

Glass-body, micro, Viscolene, non-refillable, combination pH electrode.
Use: biotechnology, micro titration.

HI 1131B

Glass-body, double junction, refillable, combination pH electrode.
Use: general purpose.

120 mm

4.7"

12 mm

0.5"

9.5mm DIA

0.37"

"S" VERSION

HI 1043

120 mm

4.7"

12 mm

0.5"

"S" VERSION

HI 1053

120 mm

12 mm

0.5"

5 mm

0.2"

3 mm

0.12"

3.0 mm DIA

0.12"

HI 1083

120 mm

4.7"

12 mm

0.5"

9.5mm DIA

0.37"

"S" VERSION

HI 1131

10

pH BUFFER TEMPERATURE DEPENDENCE

Temperature has an effect on pH. The calibration buffer
solutions are affected by temperature changes to a lesser
degree than normal solutions.
For manual temperature calibration please refer to the following chart.

For instance, if the buffer temperature is 25°C, the display
should show pH 4.01, 7.01 or 10.01 at pH 4, 7 or 10
buffers, respectively.
At 20°C, the display should show pH 4.00, 7.03 or 10.06.
The meter reading at 50°C will then be 4.06, 6.98 or 9.82.

PMET SREFFUBHp

Cº Fº 10.4 68.6 10.7 81.9 10.01

0 23 10.4 89.6 31.7 64.9 23.01

5 14 00.4 59.6 01.7 93.9 42.01

01 05 00.4 29.6 70.7 33.9 81.01

51 95 00.4 09.6 50.7 72.9 21.01

02 86 00.4 88.6 30.7 22.9 60.01

52 77 10.4 68.6 10.7 81.9 10.01

03 68 20.4 58.6 00.7 41.9 69.9

53 59 30.4 48.6 99.6 11.9 29.9

04 401 40.4 48.6 89.6 70.9 88.9

54 311 50.4 38.6 89.6 40.9 58.9

05 221 60.4 38.6 89.6 10.9 28.9

55 131 80.4 48.6 89.6 99.8 97.9

06 041 90.4 48.6 89.6 79.8 77.9

56 941 11.4 48.6 99.6 59.8 67.9

07 851 21.4 58.6 99.6 39.8 57.9

57 761 41.4 68.6 00.7 19.8 47.9

08 671 61.4 78.6 10.7 98.8 47.9

58 581 71.4 78.6 20.7 78.8 47.9

09 491 91.4 88.6 30.7 58.8 57.9

59 302 02.4 98.6 40.7 38.8 67.9

15

ACCESSORIES

pH CALIBRATION SOLUTIONS

HI 70004P pH 4.01 buffer solution, 20 mL sachet, 25 pcs
HI 70007P pH 7.01 buffer solution, 20 mL sachet, 25 pcs
HI 70010P pH 10.01 buffer solution, 20 mL sachet, 25 pcs
HI 7004L pH 4.01 buffer solution, 500 mL
HI 7006L pH 6.86 buffer solution, 500 mL
HI 7007L pH 7.01 buffer solution, 500 mL
HI 7009L pH 9.18 buffer solution, 500 mL
HI 7010L pH 10.01 buffer solution, 500 mL
HI 8004L pH 4.01 buffer solution in FDA bottle, 500 mL
HI 8006L pH 6.86 buffer solution in FDA bottle, 500 mL
HI 8007L pH 7.01 buffer solution in FDA bottle, 500 mL
HI 8009L pH 9.18 buffer solution in FDA bottle, 500 mL
HI 8010L pH 10.01 buffer solution in FDA bottle, 500 mL

ELECTRODE STORAGE SOLUTION

HI 70300L Storage solution, 500 mL
HI 80300L Storage solution in FDA bottle, 500 mL

ELECTRODE CLEANING SOLUTIONS

HI 70000P Electrode rinsing solution, 20 mL sachet, 25 pcs
HI 7061L General cleaning solution, 500 mL
HI 7073L Protein cleaning solution, 500 mL
HI 7074L Inorganic cleaning solution, 500 mL
HI 7077L Oil & Fat cleaning solution, 500 mL
HI 8061L General cleaning solution in FDA bottle, 500 mL
HI 8073L Protein cleaning solution in FDA bottle, 500 mL
HI 8077L Oil & Fat Cleaning solution in FDA bottle, 500 mL

ELECTROLYTE SOLUTIONS

HI 7071 3.5M KCl + AgCl electrolyte solution, 4 x 30 mL, for

single junction electrodes

HI 7072 1M KNO3 electrolyte solution, 4 x 30 mL
HI 7082 3.5M KCl electrolyte solution, 4 x 30 mL, for double

junction electrodes

HI 8071 3.5M KCl + AgCl electrolyte solution in FDA bottle, 4 x

30 mL, for single junction electrodes

HI 8072 1M KNO3 electrolyte solution in FDA bottle, 4 x 30 mL
HI 8082 3.5M KCl electrolyte solution in FDA bottle, 4 x 30 mL,

for double junction electrodes

11

Reference
Filling Hole

Reference
Filling Hole

Sensitive

Wire

Reference

Wire

Reference

Junction

Glass

Bulb

Glass
Bulb

Reference
Junction

Reference
Junction

Reference

Junction

Platinum or
Gold tip

Platinum or

Gold tip

Reference
Wire

Reference
Wire

Sensitive
Wire

Glass Body

pH Electrode

Plastic Body
pH Electrode

Plastic Body

ORP Electrode

Glass Body

ORP Electrode

Reference

Wire

ELECTRODE CONDITIONING

AND MAINTENANCE

PREPARATION PROCEDURE

Remove the protective cap.
DO NOT BE ALARMED IF SALT DEPOSITS ARE PRESENT. This is normal
with electrodes and they will disappear when rinsed with water.
During transport tiny bubbles of air may form inside the glass bulb
affecting proper functioning of the electrode. These bubbles can be
removed by "shaking down" the electrode as you would do with a
glass thermometer.
If the bulb and/or junction is dry, soak the electrode in HI 70300
storage solution for at least one hour.

Note: To prevent damage to the electrode, remove the pH

electrode from the solution before turning the meter off.
If the meter is OFF, detach the electrode from the meter

before immersing the electrode in the storage solution.

14

Alkaline Error

TEMPERATURE CORRELATION FOR pH

SENSITIVE GLASS

The resistance of glass electrodes partially depends on the temperature.
The lower the temperature, the higher the resistance. It takes longer time
for the reading to stabilize if the resistance is higher. In addition, the
response time will suffer to a greater degree at temperatures below 10°C.

Since the resistance of the pH electrode is in the range of 200 Mohm,
the current across the membrane is in the pico Ampere range. Large
currents can disturb the calibration of the electrode for many hours.

For these reasons high humidity environments, short circuits and
static discharges are detrimental to a stable pH reading.

The pH electrode's life also depends on the temperature. If constantly
used at high temperatures, the electrode life is drastically reduced.

Typical Electrode Life
Ambient Temperature 1- 3 years
90 °C Less than 4 months
120°C Less than 1 month

High concentrations of sodium ions interfere with readings in alkaline
solutions; the pH at which the interference starts to be significant
depends upon the composition of the glass. This interference is the
alkaline error and causes the pH to be underestimated. Hanna's
glass formulations have the indicated characteristics.

-10

-10

-10

Ω

-10

-10

-10

-10

Ω

2x10

9

1x10

9

2x10

8

1x10

8

2x10

7

1x10

7

-20 -10 0 +10 +20+30+40 +50 +60 +70 +80 +90 °C

1.0 Mol L-1 Na

+

0.1 Mol L-1 Na

+

Sodium Ion Correction for the Glass at 20-25°C
Concentration pH Error

13.00

13.50

14.00

12.50

13.00

13.50

14.00

0.10

0.14

0.20

0.10

0.18

0.29

0.40

12

For refillable electrodes:

If the fill solution (electrolyte) is more than 2½ cm (1") below the fill
hole, add HI 7082 3.5M KCl electrolyte solution for double junction or
HI 7071 3.5M KCl+AgCl electrolyte solution for single junction
electrodes.

For a faster response, unscrew the fill hole screw during measurements.

For AmpHel® electrodes:

If the electrode does not respond to pH changes, the battery is run
down and the electrode should be replaced.

MEASUREMENT

Rinse the electrode tip with distilled water. Immerse the tip (bottom
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 a few drops of the solution to be tested,
before taking measurements.

STORAGE

To minimize clogging and assure a quick response time, the glass
bulb and the junction should be kept moist and not allowed to dry
out.

Replace the protective cap with a few drops of HI 70300 storage
solution or, in its absence, electrolyte solution (HI 7071 for single
junction, or HI 7082 for double junction electrodes). Follow the
Preparation Procedure above before taking measurements.

NEVER STORE THE ELECTRODE IN DISTILLED OR DEIONIZED WATER.

PERIODIC MAINTENANCE

Inspect electrode and cable. The cable used for 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.
Connectors must be perfectly clean and dry. If any scratches or cracks
are present, replace the electrode. Rinse off any salt deposits.

For refillable electrodes:

Refill the reference chamber with fresh electrolyte (HI 7071 for single
junction or HI 7082 for double junction electrodes). Allow the electrode
to stand upright for 1 hour.

Follow the Storage Procedure above.

13

CLEANING PROCEDURE

General Soak in HI 7061 general cleaning solution for

approximately 30 minutes.

Removal of films, dirt or deposits on the membrane/junction:

-

Protein

Soak in HI 7073 protein cleaning solution for 15 min.

-

Inorganic

Soak in HI 7074 inorganic cleaning solution for
15 minutes.

-

Oil/grease

Rinse with HI 7077 Oil & Fat cleaning solution.

IMPORTANT: After performing any of the cleaning procedures rinse
the electrode thoroughly with distilled water, refill the reference
chamber with fresh electrolyte (not necessary for gel-filled electrodes)
and soak the electrode in HI 70300 storage solution for at least
1 hour before taking measurements.

TROUBLESHOOTING

Evaluate your electrode performance based on the following.

• Noise (Readings fluctuate up and down) could be due to:
– Clogged/Dirty Junction: Refer to the Cleaning Procedure

above.

– Loss of shielding due to low electrolyte level (in refillable

electrodes only): refill with fresh HI 7071 for single junction or
HI 7082 for double junction electrodes.

• Dry Membrane/Junction: soak in HI 70300 storage solution for
at least 1 hour.

• Drifting: soak the electrode tip in warm (approx. 50-60°C)
Hanna HI 7082 solution for one hour and rinse the tip with
distilled water. Refill with fresh HI 7071 for single junction
electrodes and HI 7082 for double junction electrodes (refillable
electrodes only).

• Low Slope: refer to the cleaning procedure above.

• No Slope: check the electrode for cracks in glass stem or bulb
and replace the electrode.

• Slow Response/Excessive Drift: soak the tip in HI 7061
solution for 30 minutes, rinse thoroughly in distilled water and
then follow the Cleaning Procedure above.