Extech Instruments PH220 User manual

USER MANUAL
Waterproof Palm pH Meter
Model PH220

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Introduction
Congratulations on your purchase of the Extech PH220 waterproof pH/mV meter. This
microprocessor-based device with tactile push-buttons is battery operated and ideal for field use.
The PH220 simultaneously displays pH and temperature. The rubber holster which protects the
meter has a magnetic backing for convenient mounting. The built-in memory (25 readings) allows
STORE, RECALL, and CLEAR functionality. Careful use of this meter will provide years of reliable
service.
Specifications
Range (Resolution)
Accuracy
Temperature
32 to 194oF (0.1°<100o; 1 o >100o)
0 to 90oC (0.1°)
± 1.8oF
± 1.0oC
pH
0.00 to 14.00pH (0.01pH)
± 0.02pH
-1999mV to 1999mV
± 2mV
Note 1: Accuracy does not include pH buffer temperature
coefficient
Note 2: Accuracy specified from 0.02pH to 13.98pH
Temperature Compensation
32 to 194oF (0 to 90oC) Automatic ‘ATC’
Power
9 volt alkaline battery
Display
Dual LCD display for simultaneous pH and temperature
readings
Over-range or open indication
Displays "HHH" for over-range or open input conditions
Displays “LLL” for under-range
pH Calibration points
4.00, 7.00, 10.00 (1, 2, or 3 point calibration can be
performed)
Auto Power OFF
10 minutes from last key-press (can be disabled)
Low Battery Indication
Fill bars in the battery display icon represent
battery power status. The fewer the bars, the weaker the
battery power.
Dimensions / Weight
4.25 x 3.00 x 1.18" (108 x 75 x 30mm) / 4.8 oz. (135g)
Accessories supplied with kit
Battery, suction cup holder, clip holder, stick electrode for
model PH220-S, standard electrode with 39” cable for
model PH220-C.

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Meter Description
1. Battery Compartment (under holster)
2. Rubber Holster
3. LCD Display
4. Function buttons
5. Electrode input
Basic Display Description
1. Measurement value
2. Battery status
3. Units of measure
4. Temperature units
5. Solution temperature
Note that there are other more specialized displays discussed later in the appropriate sections of
this manual.
Order of Operations
1. Calibrate the instrument as described in the Calibration section.
2. Select the temperature units of measure as explained in the pH measurement instructions.
3. Carefully follow all step by step instructions and electrode cleaning/rinsing
recommendations. Slight deviations in procedures can significantly affect test results.

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Calibration (pH)
The sensitivity of a pH electrode degrades over time, it is important to frequently calibrate the
meter to the electrode. pH electrodes can be thought of as batteries in that they run down with
time and use.
Calibration is performed using standard buffer solutions at room temperature (78°F [25°C]).
Buffers are solutions of a known pH that have the useful property of resisting changes in pH.
These can be purchased pre-mixed or in capsule form and are usually available in three pH
values, pH 4.00, pH 7.00 and pH 10.00.
Calibration is always performed using the pH 7.00 buffer first, followed by a second calibration.
Select pH 4 buffer for the second calibration if typical measurements will be less than pH7 or use
a pH 10 buffer if typical measurements will be greater than pH7.
In order to obtain the most accurate results possible, a pH meter should be calibrated at least
once each day.
pH Calibration Procedure
1. Place the electrode into a 7.00 pH buffer solution. Press and hold the CAL button until ‘CAL’
appears in the display.
2. The instrument automatically recognizes the solution and calibrates to that value. Note that
if the solution is inaccurate by more than 1 pH from the 4, 7, or 10 pH buffer, or if the
electrode slope is low, the instrument will assume an error and abort the calibration (‘End’
will be displayed).
3. During calibration, the pH reading flashes on the main display.
4. When calibration is complete, the instrument displays ‘SA’ followed by ‘End’and then
returns to the normal operation mode.
5. For a 2- or 3-point calibration, repeat steps 1 ~ 4. When performing a 2- or 3-point
calibration, calibrate with pH 7 buffer first, then follow with pH 4 and/or pH 10.
‘CAL’Reminder Display
When in pH measurement mode, the ‘CAL’icon will appear if a calibration has not been
performed after 15 ON/OFF cycles of the instrument. The ‘CAL’display is a only a reminder and
will turn off when the electrode is calibrated (the reminder does not affect operation).

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Measuring pH
NOTE: Electrodes should always be rinsed before and between samples
with distilled or DI (de-ionized) water to remove all traces of storage
solution, process media, or previous test solution.
1. Connect the pH electrode to the meter.
2. Turn the meter ON using the ON/OFF button . Wait for the self-test (‘SLF tSt’) to finish.
3. Use the MODE button to select pH mode. The unit of measure appears on the LCD.
4. To change the unit of measure for temperature, press and hold the MODE button for 2
seconds. The LCD reflects the current unit of measure.
5. Rinse the electrode with distilled or deionized water.
6. Place the electrode in the solution. Allow 30 seconds for the electrode/ATC to reach
thermal equilibrium with the buffer solution.
7. After the measurement stabilizes, view the pH reading on the main display. An out of range
reading is indicated by the display icon ‘HHH’. Note that ‘HHH’ will also display when the
electrode is disconnected.
8. When the test is complete rinse the electrode with distilled or deionized water.
Automatic Temperature Compensation (ATC)
The millivolt output of a pH electrode varies with temperature, and so the meter must
compensate for these variations. The PH220 automatically compensates for solution
temperature changes with the electrode’s built-in thermometer. The temperature compensation
is active when the solution temperature deviates from room temperature. The temperature of a
solution is displayed on the lower LCD line.
Automatic Power OFF
To conserve battery power, the instrument automatically shuts off after 10 minutes of inactivity.
To disable or enable this feature, follow the steps below:
To disable: With the power on, press and hold the on/off button for 2 seconds (‘oFF’
and ‘AtP’will display). The Auto Power OFF feature is now disabled.
To enable: With the power on, press and hold the on/off button for 2 seconds (‘on’and
‘AtP’will display). The Auto Power OFF feature is now enabled.
Each time the meter is turned off the Auto power OFF feature is set to the enabled mode.

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Storing and Recalling Readings
This instrument can store up to 25 measurement readings. Readings are saved even after the
instrument has been turned off.
STORE Readings
1. Take a measurement as described earlier in this manual.
2. Momentarily press the STORE/RECALL button to save the reading. The reading will be held
on the display (the ‘HOLD’and ‘STORE’icons will appear). In addition, the storage location
(1 to 25) will briefly appear on the lower LCD area.
3. Note: The temperature reading associated with the pH reading is also saved.
4. Press the STORE/RECALL button again to release the ‘hold’ feature. The instrument will
then return to normal operation.
5. Note that when all 25 storage locations are filled the instrument begins writing over the
previously stored data.
RECALL Readings
1. Press and hold the STORE/RECALL button until a number appears on the main display. This
number is the storage location for the most recent reading.
2. The number will switch off after 1 second and the stored reading will appear. The ‘RECALL’
icon will appear and remain on the entire time the recall mode is accessed.
3. While in the RECALL mode, use the STORE/RECALL button to scroll through the stored
readings. The most recent readings will show first (LAST IN –FIRST OUT).
4. Press and hold the STORE/RECALL button until the ‘End’ display appears. Release the
button and the instrument will return to the normal operation mode.
5. Note that if there are no readings in memory, the display will show ‘End’when the user
attempts to access the RECALL mode.
ERASE (Clear) Readings
1. Press and hold STORE/RECALL and the CAL buttons simultaneously for 4 seconds.
2. The ‘CLr’ display will appear indicating that all readings have been erased.
3. Release the buttons to return to the normal operation mode.
Temperature Offset Adjustment
This instrument allows you to offset the temperature display by ±9oF (±5oC):
1. Press and hold the CAL, MODE, and STORE/RECALL buttons simultaneously for 6 seconds.
2. The main display will indicate the current offset. The lower display will show ‘t_O’.
3. Use the CAL button to decrease the offset value; use the MODE button to increase it.
4. Press and hold the STORE/RECALL button for 2 seconds to exit. The instrument will display
‘SA’(save) and ‘End’before returning to the normal operation mode.
5. The temperature display will now indicate the actual temperature ± the offset value.

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Battery Replacement
The 9V alkaline battery that powers the instrument requires replacing when all battery icon ‘fill
bars’are depleted. To replace the battery, follow the steps below:
1. Disconnect the electrode.
2. Remove the instrument’s protective jacket by pulling it over the top of the meter (ensure that
the electrode is disconnected).
3. Pry the battery compartment up from the top of the meter using a screwdriver or coin at one
of the two indentations (see diagram).
4. Replace the 9V battery.
5. Insert the battery compartment into the instrument until the compartment is flush with the
top of the instrument. The compartment can only be fully inserted in one direction; the
battery compartment is labeled showing the correct orientation.
6. Replace the protective holster.

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Electrode Maintenance and Troubleshooting
Most pH measurement difficulties can be traced to the electrode. Careful handling and proper
storage of the electrode will optimize measurement accuracy and electrode life. Electrodes should
be rinsed to remove all traces of storage solution, process medium, or previous test solution.
Electrode Storage
The electrode should be stored in a soaker bottle or wetting cap filled with pH4 buffer. Never store
an electrode in distilled or deionized water as this will cause migration of the fill solution from the
electrode.
Electrode Cleaning
The type of electrode coating that occurs over time will determine the cleaning method. Soft
coatings can be removed by vigorous stirring or by using a squirt bottle. Organic chemical coating
(hard coatings) should be chemically removed. Only in extreme cases should the bulb be cleaned
mechanically.
Electrode Troubleshooting
Symptom
Cause
Recommendation
Long response time or
reading drift
Clogged Junction
Soak in 4.07 M Potassium Chloride (KCl) @
140oF (60oC) for 30 minutes.
Strong Alkaline measurement
Soak in 0.1 M HCL overnight.
Deteriorated Gel layer
Replace electrode.
Protein coating on electrode
surface
Soak in 1 gm Pepsin dissolved in 100ml of 0.1
m HCL for 30 minutes or as needed.
Oil, paint, dyes, suspended
solids etc. are on sensor
Rinse electrode alternately with a materials
solvent and a buffer 7.00.
Organic solvents are coating the
sensor
Organic mole fraction should be less than 50%
to assure reasonable readings. Limit time of
measurement. Keep probe in the 7.0 buffer
between readings.
Dehydrated membrane
Read solution for dry bulb below:
Dry Bulb
Long term storage without
wetting
Soak electrode tip in wetting cap filled with
1ml 7.00 buffer for 24 to 48 hours
Static Charge
Wiping electrodes
Rinse electrode in 7.0 buffer and blot. Do no
wipe electrode.
Same readings in
different buffers and
samples
Cracked or broken bulb
Replace electrode. Use bulb guard. Avoid
plunging electrode to bottom of container
and spinning bars. Wetting cap will protect
bulb between tests.
Erratic LCD display
Samples have low ionic strength
(low sodium); e.g. distilled, de-
ionized, boiled, or lake water
(high pressure)
For each 50 ml of sample add 1 drop (50uL) of
SAT. KCl (No alteration in pH will occur using
inert KCl).

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Two-year Warranty
FLIR Systems, Inc. warrants this Extech brand instrument to be free of defects in parts and workmanship for
two years from date of shipment (a six-month limited warranty applies to sensors and cables). To view the full
warranty text please visit: http://www.extech.com/support/warranties.
Calibration and Repair Services
FLIR Systems, Inc. offers calibration and repair services for the Extech brand products we sell. We
offer NIST traceable calibration for most of our products. Contact us for information on calibration
and repair availability, refer to the contact information below. Annual calibrations should be
performed to verify meter performance and accuracy. Product specifications are subject to change
without notice. Please visit our website for the most up-to-date product information:
www.extech.com.
Contact Customer Support
Customer Support Telephone List: https://support.flir.com/contact
Calibration, Repair, and Returns: [email protected]
Technical Support: https://support.flir.com
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All rights reserved including the right of reproduction in whole or in part in any form
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