ST20D Pen DO meter Instruction Manual
Thank you for choosing OHAUS waterproof pen Dissolved Oxygen meter ST20D. Please read the manual
completely before use.
First Usage
Take off the membrane part, fill the electrolyte, then turn on the membrane. Warm up the DO pen meter by
turning it on. The meter will turn off automatically after 10 minutes.
Calibration and measurement
After warm up, turn on the meter. Put the ST20D in the air and press the CAL button;
The meter will display "100" and blink under the signal, now the meter is calibrating 100% DO value; after 3 to 5
minutes when the signal is stable, press the Hold/Enter button to finish 100% DO calibration.
Now we have two options:
1.
Press the Hold/Enter button to finish 1 point calibration and exit to measurement interface.
Note
：
Ohaus suggest that only do one point (100%) calibration for ST20D. Do not need perform 2
point (0%) calibration if the sample DO value is not too low (e.g. <1 mg/L).
2.
Put the ST20D into the Zero-Oxygen solution. Press the CAL button to do the 0% point calibration, LCD will
display and blink "0" under the signal, after about 3 minutes when the signal is stable, press the Hold/Enter
button to finish 0% calibration.
Zero-Oxygen solution is saturated Na
2
SO
3
(CAS NO 7757-83-7) solution. Ohaus offer DO zero-oxygen chemical
(30059257).
After calibration, rinse the pen DO tip, then we can measure the sample.
