11
Thermo Scientific Orion Star A113 Benchtop & Star A123 Portable Dissolved Oxygen Meters
Chapter 4 Calibration and Measurement
DO Calibration and Measurement
Entering Barometric Pressure
Dissolved oxygen readings are dependent on barometric pressure. This needs to be entered manually as mm Hg.
1 mm Hg = 0.03937 inch Hg = 1.3332 hPA (mBar) = 0.01934 PSI.
1. In DO measurement mode, press
.
2. Press
three times so that the top line reads “PRES”.
3. Press
or
to enter the barometric pressure.
Note:
Holding the button down will make the value change faster.
4. Press
to save configuration and
to return measurement mode.
Entering Salinity Correction Value
Since the presence of dissolved salts limits the amount of oxygen that can dissolve in water, the relationship between
oxygen concentration and partial pressure varies with sample salinity. The meter default has a salinity correction factor
of 0. To compensate for variations in ionic concentration, enter the salinity of the sample in parts per thousand (ppt). A
table of conductivity versus salinity can be found in the appendix.
1. In DO measurement mode,
press .
2. Press
four times so that the top line reads “SALT”.
3. Press
or
to enter the salinity in ppt.
Note:
Holding the button down will make the value change faster.
4. Press
to save configuration and
to return measurement mode.
