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sympHony
™
Meter User Guide
Dissolved Oxygen Calibration
• Prior to calibration, the dissolved oxygen probe must be prepared and polarized.
The probe is continuously polarized when it is connected to the meter. When
the probe is first connected or if the probe is disconnected for more than 60
minutes, connect the probe to the meter, connect the meter to a power source
and wait 30 to 60 minutes for the probe to polarize. Disconnecting the probe for
less than one hour will require 5 to 25 minutes for polarization.
• The meters will supply a polarization current to the dissolved oxygen probe even
when the meter power is off. To maximize the meter battery life, unplug the
probe if it will not be used for an extended period.
1. Select one of the following calibration modes in the setup menu.
a. – An air calibration is performed in water saturated air using the
calibration sleeve. This is the simplest and most accurate calibration. Due to
the inherent differences between water saturated air and air saturated water,
102.3% saturation will be displayed when the calibration reading is stable.
i. The highest possible accuracy is reached when calibration temperature is
the same as the measuring temperature.
ii. Moisten the sponge or absorbent cloth in the calibration sleeve with
distilled water and insert the probe into the sleeve without touching the
water saturated material. For BOD measurements, this calibration can be
performed in a BOD bottle.
b. – A water calibration is performed using water that is 100% saturated
with air. Bubble air into a water sample and gently stir the sample to prevent
the buildup of air bubbles on the dissolved oxygen probe membrane.
c. – A manual calibration is performed using a water sample with a
known concentration of dissolved oxygen. This method can be used to
calibrate the dissolved oxygen probe to the value achieved by a
Winkler titration.
Dissolved Oxygen Technique