Extech Instruments 407227 User manual

User's Guide
Heavy Duty pH, mV, & Temperature Meter
Model 407227
•Measures pH, mV and Temperature
•RS-232 PC Interface
•oC/oF switchable
•Front panel Slope and Calibration adjustments
Introduction
Congratulations on your purchase of Extech’s pH, mV, and Temperature Meter. This
professional meter, with proper care, will provide years of safe reliable service.
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Model 407227 Ver. 2.1 Oct. 2002
Page 2
Specifications
General Specifications
Display Dual function LCD with contrast adjust
Input impedance 1012 ohms
Temp. compensation for pH Automatic and manual 32 to 149°F (0 to 65°C)
pH electrode compatibility Any combination pH electrode with BNC connector
Data hold Freezes displayed reading
Memory recall Records / Recalls MAX (maximum), MIN
(minimum), and AVG (average) readings
Auto Power OFF Meter powers off after 10 minutes
PC Interface Serial RS-232 Communication
Over range indication All dashes on display "- - - -"
Sampling time Approximately 0.8 seconds
Operating conditions 32°F to 122°F (0°C to 50°C); < 80% RH
Power supply 9V battery (power consumption 5.7mA approx.)
Weight 0.59 lbs. / 270g (including batteries)
Dimensions 7.1 x 2.8 x1.3" (180 x 72 x 32mm)
Optional accessories ORP Electrode, AC adaptor, datalogger, and data
acquisition WindowsTM software
Range Specifications
Measurement Range Resolution Accuracy (of reading)
pH 0 to 14 pH 0.01 pH ± (0.03 pH + 2 digits)
mV ±1999 mV 1 mV ± (0.5% + 1 digits)
Temperature (oC) 0 to 50oC
50 to 65oC
0.1oC± 1oC
± 4oC
Temperature (oF) 32 to 122oF
122 to 149oF
0.1oF± 1.8oF
± 7.5oF
Meter Description
1. pH Electrode input (BNC jack)
2. RS-232 PC Interface jack
3. LCD display
4. Keypad
5. pH Electrode
6. Calibration potentiometers
7. Temperature sensor input jack
8. LCD Contrast adjustment wheel
9. Protective rubber holster
10. Battery compartment and tilt stand (rear)
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Model 407227 Ver. 2.1 Oct. 2002
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Temperature Compensation
For accurate pH measurements and calibration, the temperature of the solution under test
must be known. This can be accomplished manually or automatically. Read through the steps
for each (below) and determine that best method for the application at hand:
Automatic Temperature Compensation
NOTE: For Automatic Compensation, the supplied thermometer must be used. Perform
these steps before each use or when the temperature of the solution under test changes.
The thermometer can remain in the solution while taking pH measurements in order to
track temperature changes and compensate for them if necessary.
1. Select ‘pH ATC’ on the meter’s front panel slide-switch.
2. Plug the supplied thermometer into the meter’s temperature sensor input jack.
3. Place the other end of the thermometer into the solution under test.
4. Perform a pH Calibration or take a pH measurement as described later in the manual.
Manual Temperature Compensation
NOTE: For Manual Compensation, an external thermometer is required (separate from the
one supplied with the meter). Perform these steps before each use or when the
temperature of the solution under test changes
1. Place a thermometer in the solution under test and note the reading.
2. Select ‘pH MTC’ on the meter’s front panel slide-switch.
3. Press the "MTC" key and 25.0oC will display on the LCD temperature display line.
Using the ">>" key (for 1 oC steps) and the ">" key (for 0.1oC steps), edit the displayed
temperature. Continue editing until the displayed temperature equals the measured
temperature that was noted earlier.
4. Perform pH calibration or pH measurement normally.
Calibrating a new thermometer
1. Connect the thermometer to the meter’s temperature sensor input jack.
2. Select "pH ATC" via the meter’s front panel slide-switch.
3. Place the temperature probe and a mercury thermometer in water.
4. Adjust VR6 (inside the battery compartment, see diagram below) until the displayed
value matches the mercury thermometer reading.
VR6
Inside battery compartment
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Model 407227 Ver. 2.1 Oct. 2002
Page 4
pH Operation
IMPORTANT NOTE: Manual or Automatic Temperature Compensation (covered earlier in
this manual) must be performed before proceeding with pH calibration and pH
measurements.
pH CALIBRATION
Note that the meter must be calibrated before each use
1. Press the POWER key to turn the meter on (if it isn’t already on).
2. Connect the Combination pH electrode to the meter’s BNC input socket and place the
electrode in a pH 7 buffer solution.
3. Turn the CAL pH7 potentiometer on the front panel until the display reads 7.00
4. Rinse the electrode with distilled water.
5. Place the electrode in the pH 4 or pH 10 buffer solution.
6. Turn the SLOPE pH potentiometer until the display reads 4.00 or 10.00.
7. Rinse the electrode in distilled water.
8. Repeat as necessary.
Note that if the adjustments described above do not yield a 4, 7, or 10 pH reading, as the
case may be, the electrode may require replacing.
pH MEASUREMENTS
1. Connect the combination pH electrode to the meter’s BNC input socket.
2. Turn the meter on using the POWER key.
3. Place the electrode in the test solution and read the displayed pH value.
4. After measuring, rinse the electrode with distilled water.
ORP Operation (millivolts)
1. Connect the mV electrode (not supplied) to the BNC input jack at the top of the meter.
2. Turn the meter on using the POWER switch.
3. Select ‘mV’ (millivolts) via the meter’s front panel slide-switch.
4. Place the electrode in the test solution and read the millivolt (ORP) value.
5. Rinse the electrode with distilled water before storing.
Note that calibration is not required for the ORP function.
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Model 407227 Ver. 2.1 Oct. 2002
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Advanced Features
MIN MAX AVG Record / Recall Mode
1. Press the RECORD key (the REC indicator will appear on the LCD).
2. Press the CALL key to view the highest (MAX) reading recorded since the RECORD
key was first pressed. The MAX indicator will appear on the LCD.
3. Press the CALL key to view the lowest (MIN) reading recorded since the RECORD key
was first pressed. The MIN indicator will appear on the LCD.
4. Press the CALL key to view the average (AVG) reading recorded since the RECORD
key was first pressed. The AVG indicator will appear on the LCD.
5. Press the RECORD key again to exit this mode.
6. Note that the Auto Power OFF feature is disabled in this mode.
Automatic Power OFF Feature
This meter is equipped with a battery conservation feature that automatically shuts off the
power after approximately 10 minutes. To defeat this feature, put the meter in the MIN
MAX AVG Record / Recall mode by pressing the RECORD key. To turn the meter off, exit
the Record mode first (by pressing the RECORD key until the RECORD display icon
switches off) and then pressing the POWER key.
Data Hold
Press the HOLD key to freeze the displayed reading. The DH indicator will switch on in the
Data Hold mode. Press the HOLD key again to exit the Data Hold mode and the DH
indicator will switch off.
RS-232 Serial PC Interface
The 407227 is equipped with an RS-232 serial data port. This interface was designed to
operate with the Extech Data Acquisition Software (Part Number 407001). For detailed
information contact your distributor or refer to the 407001 manual.
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Model 407227 Ver. 2.1 Oct. 2002
Page 6

Support Hotline [phone]
Tech support: Ext. 200; Email: [email protected]
Repair/Returns: Ext. 210; Email: [e-mail]
Website: www.extech.com
Battery Replacement
The low battery indicator (LBT) appears on the LCD when the 9V battery needs replacing.
1. Remove the meter's rubber protective holster.
2. Open the battery compartment using a small coin or screwdriver.
3. Replace the 9V battery and re-assemble the meter.
Calibration and Repair Services
Extech offers complete repair and calibration services for all of the products we sell. For
periodic calibration, NIST certification or repair of any Extech product, call customer
service for details on services available. Extech recommends that calibration be performed
on an annual basis to insure calibration integrity.
Warranty
EXTECH INSTRUMENTS CORPORATION 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 on 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 at www.extech.com (click on ‘Contact Extech’ and go to ‘Service Department’ to request an RA
number). 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.
Copyright © 2002 Extech Instruments Corporation.
All rights reserved including the right of reproduction in whole or in part in any form.
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