WT-HR – Water Level & Temperature Data Logger

The WT-HR is a Three Channel, High Resolution (12 bit), Water Height and Dual Temperature data logger fitted with a water height probe.

A temperature sensor is located at the bottom of the water probe and another is mounted in the logger so both water and air temperatures can be logged.

1 to 5 year battery life depending on usage as below, factory replaceable. Data is retained in the event of battery failure. Battery Status Monitor in Omni7 Software.

• Warning: When using the Average, Maximum or Minimum reading(s), the logger reads the attached sensor(s) every second. This will reduce battery life.
• Using the logger in temperatures below -5°C (23°F) will reduce battery life.

Notes:

• The standard version of Water Logger is constructed from 304 Stainless. If the logger is used in brackish water that is warm, it can pit and corrode the stainless.
• If a logger becomes fully submerged, sometimes water can infiltrate the logger and damage the components. Usually this is in the form of a short circuit which drains the battery at an accelerated rate. If the loggers are to be deployed in an environment where it is likely they are going to be ‘overtopped’, we suggest applying a heavy duty heat shrink tape to the joins in the top part of the logger.
• A DLC3USB [USB] download cable (2m) is required to connect the WT-HR to a computer.

WT-HR Operation

Mounting:

The Logger should be mounted vertically. If the logger is in a flowing river the flow causes water to rise up on the logger giving high readings so in a river with strong flow the logger should be mounted inside a plastic pipe with holes drilled in it – this way the logger reads the real height of the river. Make sure the logger is mounted in such a way that the bottom holes (water entry ports) do not get blocked by mud or stones.

Maintenance:

The water height probe should be cleaned every six months or more frequently in dirty, salty or polluted water. Remove the probe from the logger as detailed on this page. Clean the outer tube with hot water and a lint free cloth. Carefully clean the inner rod by hand rubbing warm water (30°C or less) up and down its length. Check that no water has found its way into the inner tube. If it has, dry thoroughly before reattaching the inner tube to the logger.

Calibration:

All WT-HR loggers are fully calibrated in our factory before dispatch.

Recalibration once a year is recommended – follow the maintenance instructions above.The probe should be soaked for 24 hours before recalibration.The recalibration should be carried out at a similar temperature to where the logger is to be used.Follow the instructions in the Omni7 help file (Calibration Procedures > Water Level Calibration).

Compensating for Temperature Coefficients:

The WT-HR has a small negative temperature coefficient with respect to water temperature. If the probe is sitting in 1 metre of water and experiences a water temperature increase of 1°C, the logger will report a water height decrease of 0.65mm. If you log water temperature, the Omni7 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 Omni7 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. The water temperature has a larger coefficient than the air temperature, so if you can only afford to log one temperature it is recommended that you log water temperature.

If you attempt to start the logger without selecting both water and logger temperatures a warning message will appear.

Temperature Coefficient:

Freight note:

Because of the unusual shape of the WT-HR (long and thin), freight is calculated on a ‘volumetric weight’ basis. This will result in a higher freight charge than a ‘normal’ sized package of the same actual weight.

For International shipments please visit the DHL website for more information about Volumetric Weight.