5.3.2
Air (Slope) Calibration
1. Place the ST-772/T sensor in the air with a stable temperature or in air-saturated water.
2. Let the ST-772/T sensor stand for a minimum of 6 minutes. Observe the values being displayed on
the
Calibration
screen.
3. Once the displayed oxygen and temperature values are stable, press
Air Calibration
to perform an air
(slope) calibration.
4. Enter the humidity value:
• If you are using air for calibration, you will need to enter the real-time (current) humidity value.
• If you are using air-saturated water for calibration, you will need to enter a humidity value of
”1”.
5. If the air (slope) calibration was successful, the interface will return a message ”Calibration Suc-
ceeded”. If the calibration fails, press
Air Calibration
again and repeat.
5.3.3
4–20mA Span
The default 4–20mA span is 20 mA = maximum range (20 ppm) and 4 mA = 0 ppm dissolved oxygen in water.
Press
4–20mA Span
to change the dissolved oxygen in water value corresponding to the 20 ppm (maximum
range) output.
*
NOTE
*
The 4–20mA Span feature allows users to reduce the upper 20 mA output scale
only. It cannot increase the upper limit of the sensor.
ST-772/T User Manual
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