PS-3224
Theory of Sensor Operation
9
013-16057A
*Salinity is a unitless measurement determined from conductivity and temperature readings according to the
Practical Salinity Scale. Historically, salinity values determined with the Practical Salinity Scale were given the
designation “ppt” because these values were very close to those determined by the previously used method where
the mass of dissolved salts in a given mass of water (parts per thousand) were reported.
Probe Care and Maintenance
The sensing layer inside the Sensor Cap degrades over time due to bleaching caused by exposure to light, so the
Sensor Cap must be replaced periodically. It should also be replaced if it is cracked, scratched, or damaged. The
Sensor Cap is warranted for one year and may last much longer. The working life of a Sensor Cap may be
extended by keeping it clean and properly stored between uses. The replacement Probe Sensor Cap for the
Wireless Optical Dissolved Oxygen Sensor is model number PS-3604 (see www.pasco.com for more information).
NOTE: Do not remove the Sensor Cap except to replace it with a new cap.
To clean the Sensor Cap, rinse it with clean water and dry it with a lint free cloth. If necessary, use a mild detergent.
Do not use alcohols or other organic solvents that may deteriorate the oxygen permeable diffusion layer and the
sensing layer (dye layer). When changing the Sensor Cap, rinse the clear front surface of the nose-piece of the
probe with clean water and then dry the surface with a lint free cloth or lens tissue.
Optical Dissolved Oxygen Probe Attacking Liquids
Alcohols will remove the paint layer of the Sensor Cap. The following will remove the paint and dye layers of the
Sensor Cap and will attack the probe housing as well:
Storage
The Optical Dissolved Oxygen Probe should not be allowed to dry out. For storage, keep the Sensor Cap installed
on the probe. Moisten the small disk-shaped sponge that is in the end of the Rubber Boot (Sensor Cap Cover), and
place the end of the probe in the Rubber Boot so that the Sensor Cap is next to the moist sponge.
Do not store the probe directly in water since that would encourage algae growth on the probe.
Experiments
These are some of the experiments that can be done using the Optical Dissolved Oxygen Sensor.
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Photosynthesis, Respiration and Fermentation labs
•
Monitoring Water Quality
•
Measuring Net Primary Productivity
•
Modeling Ecosystems
•
Biochemical Oxygen Demand
Toluene
Benzene
Carbon tetrachloride
Chloroform
Methylene chloride
Acetone
Methyl ethyl ketone
Organic solvents
