- 10 -
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)
Optical dissolved oxygen probes have better stability and smaller calibration drift
compared to conventional electrochemical dissolved oxygen electrodes, which means
that the instrument can maintain its calibration data for a few months. However, for
optimal accuracy, it is recommended that the oxygen saturation calibration be performed
according to section 6.1 before use every day.
(B)
Drying of the surface coating of the sensor cap can adversely affect the stability of the
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 P3.5,
the meter will be calibrated to the theory 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.
Note:
the brief stirring of the probe in solution is only to eliminate bubbles. Unlike
conventional galvanic/polarographic electrodes, the measuring via optical dissolved
oxygen probes does not require constant stirring of the solution or flowing fluid.
7.2 Users can read the measurements when appears and stays on. Note that the
measurement time is related to temperature. When the solution temperature and the probe
temperature is close, it takes about one minute to get the readings stablized. When the
solution temperature and the electrode temperature differ a lot, it takes about 3 minutes to
reach a stable reading. This is because the reading of dissolved oxygen is heavily
