Water Level Calibration

If you are not familiar with the concept of compensating for temperature coefficients, see the section at the bottom of this page.
Lower the Water Level logger into the water to the first index mark (at the bottom of the water level probe)
Enter 0 into the First Point Actual Value box
Click on the First Point button
Lower the Water Level logger into the water to the second index mark (at the top of the water level probe under the breather hole)
Enter the height of the probe into the Second Point Actual Value box ( this could be 500mm 1000mm 1500mm or 2000mm)
Click on the Second Point button
Click on the Write Unit, Scaling and Calibration values to the Logger button
Calibration is now complete

Example

Calibration of a 1 meter Water Height Logger

Lower the Water Level logger into the water to the first index mark (at the bottom of the water level probe)
Enter 0 into the First Point Actual Value box (0mm)
Click on the First Point button
Lower the Water Level logger into the water to the second index mark (at the top of the water level probe under the breather hole)
Enter 1000 into the Second Point Actual Value box ( 1 meter = 1000mm)
Click on the Second Point button
Click on the Write Unit, Scaling and Calibration values to the Logger button

Compensating for Temperature Coefficients.

The WT-HR water height probe has a small negative temperature coefficient with respect to water temperature. If the probe is sitting in 1 meter of water and experiences a water temperature increase of 1°C, the logger will report a water height decrease of 0.6mm. If you log water temperature, the Omnilog software can compensate the logged water height value to correct the small negative temperature coefficient of the probe.

In addition to this, the logger has a small positive temperature coefficient with respect to air temperature. If a probe is sitting at 0mm of water and experiences an air temperature increase of 1°C, the logger will report a water height increase of 0.5mm. If you log air temperature, the Omnilog software can compensate the logged water height value to correct the small positive temperature coefficient of the logger.

Logging both water and air temperature, as well as water height, decreases the number of samples you can store in the logger. If the air and water temperature are going to be reasonably constant, (eg. down a well) you can log water height only. You can also log water height only if your required accuracy is greater than 10mm.

If you attempt to start the logger without selecting both water and logger temperatures, a warning message will appear. This message informs you that the readings will not be compensated but allows you to start the logger without compensation if you choose to.