Extech PH300 Operating Manual

User's Guide

Digital pH Meter

Model pH300

Introduction

Congratulations on your purchase of the Extech pH meter. For best results, please read

the entire manual before use.

The pH300 meter measures pH, mV, and temperature parameters. The built-in
microprocessor provides automatic calibration, automatic temperature compensation,
data storage, and self-diagnostics. The meter can recognize up to 13 types of pH
standard buffer solutions.

The meter’s digital filter improves measurement speed and accuracy.

Two special modes (ammonia and purified water) are provided.

The meter offers a backlit LCD display and is dust-proof and water-proof, meeting the
IP57 rating

This meter is shipped fully tested and calibrated and, with proper use, will provide years
of reliable service.

Supplied Equipment List

• pH300 Meter

• pH / ATC (Automatic Temperature Compensation) Electrode

• Standard buffer solutions (4.00pH, 7.00pH, and 10.01pH) / 50ml

• Screwdriver (for removing battery compartment)

• Batteries (2 x ’AA’ 1.5V)

• User’s Guide

• Carrying Case

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Meter Description

1. LCD Display (detailed in section below)

2. Rubber protective jacket (remove to access the rear battery compartment)

3. Keypad (detailed in section below)

4. Electrode connection jack

5. Electrode plug

6. Electrode measuring bulb

7. Electrode body

8. Electrode cable

Display Description

1. Parameter Mode icon

2. Measurement reading

3. 888 (Stored data serial number),
M+ (measurement to be stored
icon), RM (reading to be recalled
icon)

4. Unit of measure

5. Temperature reading

6. Stable measurement icon

7. Calibration icons

8. Low battery icon

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Keypad Description

The meter has five (5) front panel function keys:

ON/OFF Power Key

Calibration Key:

a) When taking a measurement, press this key to enter the calibration mode
b) When in the programming mode, press this key to change the displayed

number or the ON/OFF state

Function Key

a) Press momentarily (< 1.5 seconds) to toggle between the two measurement

parameters pH and mV

b) Press and hold for at least 2 seconds to enter the P1 programming parameter.

Subsequent presses will scroll through the remaining parameters P2, P3…

Backlight and ENTER Key

a) In the measurement mode, momentary presses toggle the backlight on and off
b) When in the programming or calibration mode, press to ENTER data

MEMORY STORE and RECALL Key

a) In the measurement mode, momentary presses store the displayed readings.

Press and hold for at least 2 seconds to recall a saved reading

b) In the programming mode, press to change the displayed number or the

ON/OFF state

Store, Recall, and Clear Datalogger Memory

STORE Readings

The meter can store up to 100 pH and 100 mV readings for a total of 200 data points. To
store a reading, wait until the reading stabilizes (the smiling face icon

reading stabilizes). Press the M+/RM key momentarily to store a reading. The M+ icon
appears and the data point serial number increments.

RECALL Readings

In the measurement mode, press the M+/RM key to recall the most recently stored
reading. RM and the data point serial number for the displayed reading will appear on the
LCD. The measurement information will appear on the lower right hand side of the LCD.
Use the CAL or M+/RM buttons to scroll the remaining stored readings. Press the ENTER
key to return to the normal measurement mode.

CLEAR Readings

From the RECALL mode, press and hold the ENTER key for at least five (5) seconds. The
LCD display will show ‘CLR’ indicating that all of the stored readings have been erased.
The unit will automatically return to the normal measurement mode after approximately 2
seconds.

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pH Measurement Mode

Preparation for Measurement

1. Turn the meter ON using the power key

2. Press the MODE key momentarily to switch to the pH mode, if necessary

3. Unscrew the protective cap on the probe jack located on the bottom of the meter (store
the protective cap in the carrying case for later use)

4. Carefully connect the pH probe to the meter’s probe jack. The probe can only be
inserted in one orientation. Once it is firmly connected, screw the probe collar onto the
meter to secure the probe.

3-Point Calibration (7.00pH, 4.00pH and 10.01pH)

Note: Calibrate the unit once per day for best results.

1. Press the CAL key to enter the Calibration mode. The meter’s display will show a
blinking ‘Cl’

2. Rinse the probe in distilled water, allow it to dry, and submerge it into a pH 7.00 buffer
solution. Stir the solution briefly and allow it to stay in the buffer solution until a stable
reading is reached

3. Press CAL again and the display will show a blinking ‘7.00’

4. This portion of the calibration procedure is complete when the display stops blinking
and shows the ‘C2’ icon. The unit will automatically switch to the second point of the
calibration

5. Rinse the probe in distilled water again, allow it to dry, and submerge it into a pH 4.00
buffer solution. Stir the solution briefly and allow it to stay in the buffer solution until a
stable reading is reached

6. Press CAL again and the display will show a blinking ‘4.00’

7. This portion of the calibration procedure is complete when the display stops blinking
and shows the ‘C3’ icon. The unit will automatically switch to the third point of the
calibration

8. Rinse the probe in distilled water again, allow it to dry, and submerge it into a pH 10.01
buffer solution. Stir the solution briefly and allow it to stay in the buffer solution until a
stable reading is reached

9. Press CAL again and the display will show a blinking ‘10.01’

10. After the display stabilizes the 3-point calibration icon will appear

1-Point and 2-Point Calibration

Note that the user can calibrate one or two points only, if the expected measurement is
known.

For example, if the expeced pH is 4pH, it is acceptable to perform only a 1-Point
Calibration (4pH). If the expected measurement is between 4.00pH and 7.00pH, the user
can perform a 2-Point Calibration (4.00 and 7.00pH), and so on.

For a 4pH calibration, only the circled L will appear on the LCD. For a 7.00pH, only the
circled M will appear on the LCD. For a 10.01pH Calibration, only the circled H will appear
(Low, Medium, and High).

For all other applications, a 3-Point Calibration is recommended. Always perform a 3-Point
Calibration on new probes and probes that have been in use for long periods. This
maximizes measurement slope linearity.

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Testing the pH of a Sample

1. Perform the pH Calibratoin as described above

2. Rinse and dry the pH Probe and submerge it in a sample liquid

3. Stir the solution briefly with the probe and allow it to stand until the display stabilizes

4. Note that the closer the temperature of the sample solution to the calibration solution,
the more accurate readings

Programming pH Parameters

The Table below shows the available programming menu items P1 ~ P7. Each parameter
is explained in detail in the subsequent sections.

Parameters Code Selections

P1 pH buffer solution series selection

Distilled water pH temperature

P2

compensation setting (see note

below this table)

Distilled water with Ammonia pH

P3

temperature compensation setting

(see note below this table)

P4 Temperature unit setting ℃ / ℉

P5 Back light display time setting 0-1-3-6min

P6 Auto power off setting 0-10-20min

P7 Restore to default factory settings OFF / ON

Notes on P2 and P3 Parameters: Measurements of distilled water and distilled water

mixed with ammonia affect the temperature compensation and the slope linearity of the pH
probe. Such measurements are sometimes used in the electrical power and petrochemical
industries. Set these parameters to ON only if necessary, otherwise leave these
parameters in the OFF state.

OFF / ON

OFF / ON

USA (Europe & U.S.A)

NIS (NIST)

CH (China)

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Parameter P1 (pH Buffer Solution Setting)

1. From the pH measurement mode, press and hold MODE for at least 2 seconds and
then release, the ‘P1’ icon appears on the LCD

2. Use the CAL or the M+/RM keys to toggle through the three (3) selections: USA (for
use in the USA or Europe, NIS (for NIST calibration purposes), and CH (for use in
China)

3. Momentarily press MODE to move to the next parameter (P2), or press ENTER to
return to the normal measurement mode

Parameter P2 (Distilled Water Temperature Compensation Setting)

1. From the P2 menu, use the CAL or the M+/RM keys to turn this feature ON or OFF

2. Momentarily press MODE to move to the next parameter (P3), or press ENTER to
return to the normal measurement mode

3. See the Note below the Table in the previous section for more details on parameter P2

Parameter P3 (Distilled Water with Ammonia Temperature Compensation Setting)

1. From the P3 menu, use the CAL or the M+/RM keys to turn this feature ON or OFF

2. Momentarily press MODE to move to the next parameter (P4) or press ENTER to
return to the normal measurement mode

3. See the Note below the Table in the previous section for more details on parameter P3

Parameter P4 (Temperature Measurement Units Setting)

1. From the P4 menu, use the CAL or the M+/RM keys to turn this feature ON or OFF

2. Momentarily press MODE to move to the next parameter (P5) or press ENTER to
return to the normal measurement mode

Parameter P5 (Display Backlight Setting)

1. From the P5 menu, use the CAL or the M+/RM keys to select 0, 1, 3, or 6 minute
default backlighting time

2. Momentarily press MODE to move to the next parameter (P6) or press ENTER to
return to the normal measurement mode

Parameter P6 (Automatic Power OFF Setting)

1. From the P6 menu, use the CAL or the M+/RM keys to select a 0, 10, or 20 minute
Auto Power OFF time

2. Momentarily press MODE to move to the next parameter (P7) or press ENTER to
return to the normal measurement mode

Parameter P7 (Restore Factory Default Settings)

1. From the P7 menu, use the CAL or the M+/RM keys to select ON (reset the factory
default settings) or OFF (cancel edit)

2. Momentarily press MODE to move to the first parameter (P1) or press ENTER to return
to the normal measurement mode

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pH Measurement, Calibration, and Electrode Considerations

• Error messages ERR-1: Electrode zero potential error and ERR-2: Electrode slope
error; For either error, check the following:

1. Air bubbles in the electrode bulb. Shake rigorously to remove air bubbles

2. Accuracy of the pH buffers used in calibration. Replace buffers if necessary

3. Set meter to its factory default state in Parameter P7 (previous section of manual)

• Calibration intervals depend on the sample, the electrode performance, and the
required accuracy. For high accuracy measurements (≤ ±0.02pH), the meter should be
calibrated immediately before taking a measurement. For general accuracy (≥±0.1pH),
the meter can be calibrated and used for approximately one week before the next
calibration.

• The meter must be recalibrated in the following situations:

1. New probe, or probe that is unused for a long period of time

2. After measuring acids (pH<2) or alkaline solutions (pH>12)

3. After measuring a solution that contains fluoride or a concentrated organic solution

4. If the solution’s temperature differs widely from the calibration solution temperature

• The soaking solution contained in the supplied protective bottle is used to maintain
activation in the glass bulb and junction. Loosen the capsule, remove the electrode and
rinse in purified water before taking a measurement. Insert the electrode and tighten
the capsule after measurements to prevent the solution from leaking. If the soak
solution is turbid or moldy, replace the solution.

• To prepare a soak solution: Use 25g pure KCL dissolved with purified water and diluted
to 100mL. The electrode should not be soaked in a purified water protein solution or an
acid fluoride solution for long periods of time. In addition, do not soak the electrode in
organic silicon lipids.

• For calibration accuracy, the pH of the standard buffer solution must be reliable. The
buffer solution should be refreshed often, especially after heavy use.

• For best accuracy, always keep the meter clean and dry, especially the meter’s
electrode and electrode jack. Clean with medical cotton and alcohol if necessary.

• The sensitive glass bulb at the front of the combination electrode should not come in
contact with hard surfaces. Scratches or cracks on the electrode will cause inaccurate
readings. Before and after each measurement, the electrode should be washed with
purified water and dried. Do not clean the glass bulb with a tissue for it will affect the
stability of the electrode potential and increase the response time. The electrode
should be thoroughly cleaned if a sample sticks to the electrode. Use a solvent if the
solution does not appear clean after washing.

• Electrodes that have been used over a long period of time, used in a strong solution
that has damaged the sensitive bulb, or used with a substance resulting in a jam at the
junction will be become passivated; the sensitivity will decrease, its response will slow,
and the readings will be inaccurate. Replace the electrode as soon as possible in these
cases.

• For abnormal readings, try calibrating again; if the problem persists replace the
Electrode. The user can also try resetting the meter to factory default conditions per
Parameter P7 (detailed in an earlier section). Electrode life can be shortened by heavy
use, extreme conditions, and improper maintenance.

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Measuring the millivolt value for a sample solution

1. Turn the meter ON using the power key

2. Momentarily press MODE to switch to the mV mode, if necessary

3. Connect the electrode to the meter

4. Immerse the electrode in the sample solution, slowly stir the solution with the
electrode and then allow it to rest in the solution

5. When the smile face icon appears on the LCD, the reading has stabilized

mV Programming Parameters

Prompt Parameters Code Settings

P1

P2

Parameter P1 (Display Backlight Setting)

1. Press MODE to access the P1 Parameter

2. Use the CAL or the M+/RM keys to select 0, 1, 3, or 6 minute default backlighting
time

3. Momentarily press MODE to move to the next parameter (P2) or press ENTER to
return to the normal measurement mode

Back light display time

Auto power off time

0 -1-3-6 min

0 -10-20 min

Parameter P2 (Automatic Power OFF Setting)

1. From the P2 menu, use the CAL or the M+/RM keys to select a 0, 10, or 20 minute
Auto Power OFF time

2. Momentarily press MODE to move back to Parameter P1, or press ENTER to
return to the normal measurement mode

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Specifications

pH Specifications

Measuring range -2.00 to 19.99 pH

Resolution 0.1/0.01 pH

Accuracy Meter: ±0.01pH; Complete Kit: ±0.02pH

Input current ≤ 2×10

Input impedance ≥ 1×10

Stability ±0.01 pH/3h

Temp. Compensation range 32 to 212 oF (0 to 100 ℃) (automatic)

mV Specifications

Measuring range (mV/EH) -1999 mV to 0 to 1999mV

Resolution 1mV

Accuracy Meter: ±0.1% FS

Other Technical Parameters

-12

12

A

Ω

Data storage 200 data groups

Storage content Data serial number, measurement value, unit of measure

Power Two AA batteries (1.5V x 2)

Size and weight Meter: 2.6 x 4.7 x 1.2” (65 × 120 × 31mm) / 6.3 oz (180g)

Case: 10 x 8.3 x 2” (255 x 210 x 50mm) / 1.7 lbs (790g)

Quality / Safety certification ISO9001, CE and CMC

Working Conditions

Environment temperature 41 to 95 oF (5 to 35 ℃)

Environmental humidity ≤ 85%

IP rating IP57 Dustproof and waterproof

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Warranty

EXTECH INSTRUMENTS CORPORATION (A FLIR COMPANY) warrants this instrument to be free of

defects in parts and workmanship for one year from date of shipment (a six month limited warranty
applies to sensors and cables). If it should become necessary to return the instrument for service during
or beyond the warranty period, contact the Customer Service Department at [phone] ext. 210 for
authorization or visit our website www.extech.com for contact information. A Return Authorization (RA)
number must be issued before any product is returned to Extech. The sender is responsible for shipping
charges, freight, insurance and proper packaging to prevent damage in transit. This warranty does not
apply to defects resulting from action of the user such as misuse, improper wiring, operation outside of
specification, improper maintenance or repair, or unauthorized modification. Extech specifically
disclaims any implied warranties or merchantability or fitness for a specific purpose and will not be liable
for any direct, indirect, incidental or consequential damages. Extech's total liability is limited to repair or
replacement of the product. The warranty set forth above is inclusive and no other warranty, whether
written or oral, is expressed or implied.

Calibration and Repair Services

Extech offers repair and calibration services for the products we sell. Extech also
provides NIST certification for most products. Call the Customer Care Department for
information on calibration services available for this product. Extech recommends that
annual calibrations be performed to verify meter performance and accuracy.

Technical Support: Extension 200; E-mail: [e-mail]

Repair & Returns: Extension 210; E-mail: [e-mail]

Product specifications subject to change without notice

For the latest version of this User Guide, Software updates, and other

up-to-the-minute product information, visit our website: www.extech.com

Extech Instruments Corporation, 285 Bear Hill Road, Waltham, MA 02451

Support line [phone]

Copyright © 2009 Extech Instruments Corporation (a FLIR company)

All rights reserved including the right of reproduction in whole or in part in any form.



ISO9001 Certified

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