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the probe. Tighten the locking cap. Be careful not to have water droplets on the head of
the sensor cap. Wait for 5 to 10 minutes after turning on the instrument in order to
saturate the air in the calibration sleeve with water vapor. In addition, wait for the
temperature to completely stablize.
(C)
Long press to enter the calibration mode, and
CAL
is flashing in the upper right
corner. Wait for the stable to appear and stay on, press
to finish calibration,
once
100%
starts flashing, the saturated oxygen calibration is completed.
6.2
Zero-Oxygen Calibration
Zero-Oxygen calibration is only performed when a probe or sensor cap is replaced, the
probe has not been used for a long time, or users have a requirement for high accuracy in
low DO range (0 to 2.0 ppm). Zero-Oxygen calibration is done at the factory before shipment,
so it is not necessary to perform it during initial use. Zero-oxygen calibration should follow
these steps:
(A) Preparation of 100ml of oxygen-free water: in the 100ml beaker, weigh 2g of
anhydrous sodium sulfite (Na
2
SO
3
) and add 100ml of distilled or deionized water to
dissolve. Oxygen-free water is only effective within 1 hour.
(B) Put the electrode into the oxygen-free water, wait for 3 to 5 minutes after the
instrument is turned on, and wait for the temperature and DO reading to completely
stabilize. The DO reading should be very close to 0, 0.1mg/L (ppm) or so.
(C) Long press to enter the calibration mode.
CAL
will be flashing at the upper right
corner. Wait for a stable . Press and the zero-oxygen calibration is completed.
6.3
Special Notes for Calibration
(A)
To ensure the optimal measuring accuracy, please perform the calibration at the same
temperature as your samples. It is recommended that the oxygen saturation calibration
be performed according to section 6.1 before use every day.
(B)
A dried out surface coating of the sensor cap can adversely affect the stability of
measurement. Please pay special attention to this situation. See Section 4.2 (Probe
Maintenance) for details.
(C)
The instrument has factory default setting function, select YES in parameter setting P3.6,
the meter will be calibrated to the theoratical value.
7
Measurement
7.1 When measuring, place the probe in your sample solution, stir quickly for a few
seconds in the solution to remove bubbles from the measuring surface of the sensor cap.
Then hold the probe still and wait for a stable measurement. The solution must be above
the immersion line of the probe.