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• Information about LDO70 probe
The LDO70 probe uses a luminescence optical technology for dissolved oxygen measurements in water.
This type of probe has many advantages compared to classical polarographic type sensor, some of these
are:
• Zero polarization time, the instrument is always ready
• No shaking of the sample because there is no oxygen consumption
• No electrolyte in the membrane
• No interferences with other gases (e.g. CO
• Reduced maintenance time
• Very fast response time
• Accurate even with small sample volumes
• Stable and accurate measurements even at low dissolved oxygen value.
Membrane on which is fixed
the luminophore
• Measuring principle
On a permeable membrane to oxygen has been fixed a chemical substance called luminophore. Inside the
sensor, a light source pulses a light of blue colour that is reflected from the luminophore on an inner
photocell. When the oxygen, permeating through the membrane, comes in contact to the luminophore, it
modifies the blue light in proportion to the partial pressure of the oxygen. This variation is read by the
photocell which generates a proportional electrical signal.
• Probe storage
When the probe is not in use, store it in the storage cap containing distilled water. In this way, the
membrane is protected and hydrated, ready for use.
• Oxygen sensor calibration
The luminophore of the optical sensor is subject to aging and wear, therefore, you need to calibrate it
regularly in the air.
• Calibration in air at 100%
The ordinary calibration is performed at 100% in air.
Turn the instrument on, dip the probe in water and wait for the polarization time of 10 minutes.
Later, dry the probe thoroughly with paper towel and proceed as follows:
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2
O-ring
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