The WP4-T makes the difficult measurement of water potential easier. The WP4-T has a measurement range from 0 to -300MPa and 3 to 6.5 pF (saturation to airdry) with an accuracy of 0.1MPa or better.
|Accuracy:||0 to -10 MPa (3 to 5 pF) ± 0.1 MPa
-10 to -300 MPa (5 to 6.5 pF) ± 1%
|Range:||0 to -300 MPa (3 to 6.5 pF)|
|Resolution:||± 0.01 MPa|
|Measurement Time:||5-10 minutes typical for most soils, 15-20 minutes for plant tissue|
|Operating Environment:||5 to 43°C, 20 to 85% relative humidity|
|Temperature Control:||15°C to 40°C ±0.2°C|
|Shipping Weight:||5.2 kilograms|
|Case Material:||Powder coated aluminium|
|Sample Dish Capacity:||15 ml full (7 ml recommended)|
|Enclosure Size:||25.4 x 22.8 x 11.4cm|
|Sensors:||1. Infrared sample surface temperature.
2. Cooled mirror condensation dewpoint.
|Power:||110V or 220V AC, 50/60Hz|
|Communications:||9-pin D-subminiature, RS232A compatible, 8 data bit ASCII code, 9600 baud, no parity, 1 stopbit. Standard RS232A serial cable included|
The WP4-T senses the dew point of water vapour with a cooled mirror located above a sample in a closed chamber. Sample temperature is monitored with a built-in infrared thermometer, and the WP4-T’s internal peltier cooler allows you to control the sample temperature from 15°C – 40°C. Readings for individual samples are obtained rapidly (5-10 minutes for most soil samples).
Your lab temperature may vary as much as 5 degrees during the day. This results in as much as a -0.5 MPa difference in water potential readings on dry soil. Most researchers know that water potential changes with temperature. When you use the WP4-T you can measure the water potential of all your samples at a pre-set temperature. Temperature control allows you to monitor small changes in water potential from one sample to the next. By removing the temperature variables from your readings you more accurately measure water potential variations from sample to sample.