WP4C
Soil water potential lab instrumentation
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Good product
Soil science
In my experience, the WP4C represents a major step forward in sustainable and efficient laboratory practice. Compared with traditional Richard pressure chambers, it eliminates the need for high-pressure gas systems, reducing both energy use and safety risks. The chilled-mirror dew point method delivers precise measurements in just a few minutes, drastically improving workflow efficiency and cutting down on sample waste. From a sustainability perspective, the WP4C has a clear advantage: minimal power consumption, no gas cylinders to maintain or replace, and a durable design that extends instrument lifespan. It’s simple to operate, requires little maintenance, and integrates seamlessly into digital lab environments. Overall, the WP4C combines scientific accuracy with environmental responsibility — a rare case where performance and sustainability genuinely align. It’s a smart investment for any laboratory aiming to reduce its environmental footprint without compromising data quality.
Review Date: 24 Nov 2025 | METER
Water potential measurement
The WP4C is a complex instrument due to its versatility, but extremely easy to use with sample sizes up to 7 ml. Simply fill half of the cup with soil, leaves or seeds, and then equilibrate the sample.
The dew point sensor inside the WP4C is a primary measure of water potential, not some secondary parameter merely correlated with water potential. It measures the combined matric and osmotic potential using fundamental thermodynamics and a finely-tuned calibration.
Here’s how it works:
The WP4C determines the relative humidity of the air above a sample in a sealed chamber (conforms to ASTM D6836). Once the sample comes into equilibrium with the vapor, relative humidity is determined using the chilled mirror method. This involves chilling a tiny mirror until dew starts to form. At the dew point, the WP4C measures both mirror and sample temperature within 0.001 °C. This allows for unparalleled accuracy in the -0.1 MPa to -300 MPa range so you can have full confidence in sample readings.
