Aanderaa 4330 Operating Manual page 72

If you also would like to log the Optode's internal temperature sensor you will have to order the Oxygen Optode model 3930 which can output the
temperature in parallel in VR22 format.
Note this is normally not necessary as our recording instruments include a separate temperature sensor.
Newer optodes e.g. 4330, 4831 and 4835 do not have SR10 output. When connected to data loggers (using AiCaP/CAN and/or RS232 format) all data
coming from the sensor can be presented and logged including: O
MR 9
Q: Why is the sensor limited to a range of 0-120% and 0-500 µM?
A: These limitations are only present when logging the sensor in SR10 or analog formats.
If logging the sensor in RS232 or AiCaP/CAN bus there are no upper limits for the measurements range.
However the user should be aware of that the sensors and the foils are normally only calibrated to 500µM beyond these limits a lower accuracy and
precision should be expected.
AADI has however made several special deliveries of multipoint calibrated optodes that can measure with maintained accuracy up to 500 % air saturation.
To calibrate such sensors demands special efforts and consequently are more costly.
The 120% saturation limit is given for extreme conditions, which will rarely occur in reality.
At 0ºC at a salinity of 0 ppt the 100% saturation reading of water is 457µM.
It is unlikely that in such waters there would be supersaturation.seawater (35 ppt) at 0ºC contains 358µM at 100% saturation so here there is margin of up to
140% before the sensor reaches the SR10 measuring limit of 500µM.
To conclude the limitation when logging the sensor in SR10 or analog format is 500µM = 16mg /l the corresponding saturation limitations in % can be
calculated when the temperatures and salinities are known.
MR 10
Q: How fouling sensitive is the sensor?
A: The sensor does not consume any oxygen and it is not stirring sensitive therefore it is less sensitive to fouling than electrochemical sensors. Field
experiences from parallel deployments have also demonstrated that the Optodes typically can measure without effects of fouling for twice as long as the
AADI conductivity sensors.
The fouling sensitivity varies from case to case.
In the marine environment with high fouling conditions an unprotected Optode will give accurate readings as long as the fouling is not changing the local
oxygen conditions around the sensing foil.
Some user experiences have shown that this, in the worst cases, can start to occur already after 10 days in warm and highly productive waters.
Customers have adapted different strategies to improve the fouling resistance including cupper lining and wipers.
concentration, O saturation, Temperature and Raw data.
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page 72 of 93
TD 269 OPERATING MANUAL
OXYGEN OPTODE 4330, 4831, 4835
June 2017