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the response time (t
< 25 s) is sufficient but when doing fast profiling (e.g. with a CTD or on a towed vehicle) the response time can be a limiting
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factor. The 4330 and 4831 Optodes can be fitted with faster responding transparent foils that have approximately a factor 4 faster response.
RTPC 2
Q: What is the maximum sampling rate of the sensor?
A: 1 sample/second (1Hz).
If sampling at rates faster than 1 sample/5seconds please be aware of potential self heating errors (maximal error due to self heating 1-2µM).
When sampling at high rates it is better to power the sensor with 5 V (instead of higher tensions) to reduce the self heating (see above).
RTPC 3
Q: Can I check that the sensor is giving correct readings without doing any Winkler titration's?
A: Yes, if you have a glass of water that is open to the air and bubbled with an air pump (normally used in aquariums, compressor type pumps should be
avoided) the water will rapidly become approximately 100% (96-104 %) saturated and it stays saturated if you continue the bubbling.
The bubbling also ensures mixing in the glass so that oxygen gradients do not form in the water.
The absolute concentration (in µM or mg/l) in this water, at saturation, is dependent on three parameters: the salinity, the temperature and the air pressure.
For example if the salinity is 0 ppt and the temperature is 20°C the oxygen concentration should be around 284µM but this value is given for an air-pressure
of 1013 mbar.
The saturation values can be obtained from tables and/or mathematical formulas given in the Operating Manual.
If the air pressure is higher, for example 1030, you should expect higher readings of about (1030-1013) / 1013 = 27 / 1013 = 2.7% and if it is lower the
readings should be lower.
If you would like to go further with your tests you can vary the temperature in the glass either by adding ice or by heating the water.
The saturation should then stay close to 100% at all the times but the absolute concentration will increase when the temperature goes down and decrease
when it increases.
Of course the sensor should drop to low readings when you bubble the water with a different gas than air or oxygen (e.g. N
example Sodium sulphite to your water solution the sensor should read 0 oxygen.
Please note that it can take a long time before the water reaches a zero oxygen level when bubbling with gas.
Software, Settings, Communication and connection to various data loggers (including CTD's)
SSC 1
Q: How do I most easily communicate and use the sensor from my PC? How do I calibrate it and set it up?
A: Communication can be done with all Optodes using a standard Terminal program such as HyperTerminal (available in most Windows versions) or Tera
Terminal. Please refer to optode manual for details. For earlier Optode versions (e.g. 3830 and 3835) the OxyView software can be used. This software is
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TD 269 OPERATING MANUAL
OXYGEN OPTODE 4330, 4831, 4835
June 2017
or Argon). When you add for
2
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