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WT-HR Water Height

Data Logger

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The WT-HR is a Three Channel, High Resolution (12 bit), Water Height and Dual Temperature Datalogger fitted with a water height probe. Water height probes are available for:

¼ meter 250mm WT-HR 250
½    meter 500mm WT-HR 500
1    meter 1000mm WT-HR 1000
1½ meter 1500mm WT-HR 1500
2    meter 2000mm WT-HR 2000

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.

Photos and Application notes

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Specification:
Water Height:
Sensor Type
Capacitive
304 Stainless Steel Outer
316 Stainless Steel available for special orders
Working Temperature 0º C to +70º C
Accuracy ± 1% Full Scale
Resolution ± 1mm
Temperature Coefficient
Not Compensated ± 0.65mm/meter/º C Water Temp
± 0.5mm/º C Air Temp
Compensated ± 0.2mm/º C
Note: Water Height readings can be temperature compensated using Water temperature readings.
Internal Temperature:
Sensor Type Thermister
Linear accuracy over range ± 0.3º C (0º C to 70º C)
Repeatability ± 0.1º C
Long term stability ± 0.1º C
External Temperature:
Sensor Type Thermister
Sensor Position Bottom of Water Height Probe
Working Temperature 0º C to +70º C
Linear accuracy over range ± 0.3º C
Repeatability ± 0.1º C
Long term stability ± 0.1º C
Logger:
Working Temperature -30º C to +70º C
Storage Temperature -30º C to +70º C
Sampling Rate
1 second minimum
10 hours maxium
in 1 second intervals
Storage capacity
64,000 8 bit samples
32,000 12bit samples
Alarms
Two independent Alarms
Triggered on any combination of six user configurable Alarm Conditions
One alarm can be configured to dial a PocketPager
Alarms can be visually checked using the Omnilog Software
Start modes
Start immediately
Start on date/time.
Stop modes
Stop when memory is full
Stop on date/time
Loop around (continues logging)
Logging Modes
Each channel can be set to log any combination of: 
  • Point readings
  • Average reading
  • Maximum reading
  • Minimum reading
Battery
Factory Replaceable
One ½ AA 3.6V lithium cell
Five year life. 
The data is retained in the case of battery failure.
Battery Status Monitor in OmniLog Software
Download Time 35 seconds for Full Logger
Case material 304 Stainless tube
316 Stainless Steel available for special orders
Screw on end cap Plated brass
316 Stainless Steel available for special orders
Size
Logger Length Diameter Weight
WT-HR 250 515mm 20mm 395gm
WT-HR 500 820mm 20mm 588gm
WT-HR 1000 1320mm 20mm 975gm
WT-HR 1500 1820mm 20mm 1363gm
WT-HR 2000 2320mm 20mm 1750gm

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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 0.65mm. 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. 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.

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