Water level - capacitive (Odyssey)

Parameter to be measured:

Water level

Method:

Capacitive

Equipment:

Odyssey

Advantages:

• Cheap
• Logging of 64k of data
• Logger start by starting start time
• The lack of an outer shroud makes it easy to transport the probes
• Available in different lengths
• Available with 2 sizes of brass weights
• The probe fits exactly on a 32 mm (ID) PVC pipe
• You can replace the batteries yourself
• Log-interval can be event-controlled
• Very good support from the company (prompt answering emails).

Disadvantages:

• Each sensor needs to be calibrated.
• the sensor is not compensated for temperature or electrical conductivity.
• manufacture state the accuracy to be -+ 5mm, but in practice it tends to be -+1cm.
• temperature dependency: "tests in water temperatures of 0°C - 20°C have shown a variation (under estimation) of approximately 5mm" (manufacture statement).
• electrical conductivity dependency: "If the conductivity of the water is above 5000µS/cm the sensor is largely unaffected by fluctuations in conductivity whereby large changes result in very small variations in the recorded data" (manufacture statement).

What to watch out for:

• Don’t damage the wire.

Problems/Questions:

• After 2 years of use, two of my loggers would no longer connect to the computer. All others still worked fined.
• One of my loggers would only record data for a few seconds. Restarting the logger and letting it run until the storage was full seemed to take care of this.
• How do temperature/electrical conductivity influence the measurement.

Links

Projects that used the above equipment:

Other related web sites:

http://www.odysseydatarecording.com/odyssey_productsview.php?key=1