horiba LAQUAact-PD110, Инструкция по эксплуатации, Страница: 60 / 117

Dissolved oxygen measurement
44
•Preparing the zero standard solution
Add 50 g sodium sulfite (Na
2
SO
3
) into 1000 mL pure water (or deionized water) and stir
it until sodium sulfite completely dissolves.
• Calibrating in the dissolved oxygen measurement mode
When you perform two-point calibration in the dissolved oxygen measurement mode,
calibrate in the order from a high-concentration solution to a low-concentration solution.
1. Clean the membrane at the tip of the DO
electrode with pure water (or deionized water)
and wipe it with a soft cloth at least 10
minutes before calibration.
Be careful not to break the membrane at the tip
of the electrode.
2. Prepare the standard solution to be used for
calibration.
3. Press the key to change to dissolved
oxygen measurement mode.
4. Immerse at least 6 cm of the tip of the DO
electrode in the calibration solution.
In two-point calibration, immerse it in the high-
concentration solution first.
In order to immerse the temperature sensor in
the standard solution, make sure to immerse the
electrode surely.
During measurement, use a stirrer to stir the
standard solution at 1000 rpm to 1500 rpm.
Note
・
If the temperature of the standard solution rises due to the use of a stirrer, use a
temperature controlled bath.
・
When using an electrode "9551-20D" or "9551-100D", immerse at least 9 cm from the tip.
5. Press the key to enter the calibration mode.
Stability judgment starts and the DO icon blinks. When the value is stabilized, the DO
icon changes from the blinking state to the lit state.
The screen for entering a calibration value is displayed.
6. Enter the DO concentration value of the solution to be used for calibration.