DO700-en-GB_v2.3 3/15
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pH Measurement Mode
Preparation for Measurement
1. 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).
2. 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. Turn the meter on using the power key
.
4. Press the MODE key momentarily to switch to the pH mode only if the meter is in the mV mode.
Otherwise, the unit of measure should already display pH units.
3-Point Calibration (7.00pH, 4.00pH and 10.01pH)
1. Press the CAL key to enter the Calibration mode. The meter’s display will show a blinking ‘C1’
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
A one or two point calibration is acceptable if the expected measurement result 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.
Press the ENTER key to exit the Calibration mode.
