VIII-5
Orion Star Series Meter
Thermo Electron Corporation
Dissolved Oxygen Technique
DO Calibration
Prior to calibration the probe must be prepared and polarized.
• The DO probe is continuously polarized when connected to the meter. When
first connected, or after an interval of more than 60 minutes has elapsed
since the probe was last connected, allow 30 to 60 minutes for polarization.
Interrupted connections of less than one hour will take 5 to 25 minutes for the
readings to stabilize.
• Zeroing the Probe – a DO probe can generate a 0.02 to 0.05 mg/L positive error
in an oxygen free (anoxic) solution. If this error is unacceptable, then zero the
probe when using a new sensing membrane, using fresh filing solution, or when
measuring dissolved oxygen below 1 mg/L or 10% saturation.
An air calibration should be done prior to the zero calibration.
1. In the measurement mode press
.
2. Press
/ until is shown on the top line.
3. Press
to confirm the setting and move the arrow to the middle line.
4. Press
/ to scroll to .
5. Press
to select setting and move arrow icon to the bottom line.
6. Press
/ to select one of the following calibration modes.
a.
denotes calibration performed in water saturated air using the
air calibration sleeve. This is generally the simplest and most accurate
calibration method. It is also the meter’s default setting. If the calibration
selection in has not been changed, then pressing will automatically
perform an Air calibration. Due to the inherent differences between water-
saturated air and air-saturated water, upon stability, the air standard is set to
102.3 % saturation.
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