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

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).

9PH220-en-US_v3.53/21

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

www.extech.com

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