WP4C Dewpoint Potentiameter

Fast, Accurate Water Potential Measurements
Use the WP4C to measure water potential in 5 to 10 minutes.
Range: -0.1 to -300 MPa

Decagon - WP4C Introduction Video

Case Study – Survival of Australian plague locust eggs in relation to soil type and moisture retention

Versatile

The WP4C can be used to measure the water potential of any porous material. It's typically used to analyze soil, soilless substrate, plant material, and seeds, but it has been used to measure a variety of unusual things, including apples, bricks, oil, and insect carapaces.

Easy Operation

The WP4C is a bench-top instrument. To measure water potential, you place the sample in a round sample cup (4cm in diameter and 1cm tall) and set the cup in a lexan sample drawer. You slide in the drawer and turn a knob to seal the chamber. After about 5 minutes, the WP4C will beep and show your final water potential reading.

Precise Mode

Measurements can be inaccurate if they're made too soon. When run in Precise Mode, the new WP4C checks to make sure the sample has fully come to equilibrium before displaying a final reading.

Faster Equilibration

The WP4C's new nickel Teflon sample chamber coating is hydrophobic. Less water absorption in the sample chamber means faster equilibrium.

Finely Tuned Calibration

The WP4C sensor is durable and easy to clean. The instrument can be calibrated using saturated salt solutions (mix your own or order single-sample sized vials of standards on the accessories tab). New algorithms let you fine-tune calibration for excellent accuracy (±0.05 MPa or better).

Features

All the WP4's features are conveniently packaged in a bench-top enclosure with an integral sensor drawer. Readings take only one step - simply close the sample drawer to initiate sensor chamber readings. You can transfer water potential data to a computer via a RS232 cable.

Easy-to-clean one piece sensor: Faster cleaning for less downtime.
Tuf-BlockTM sensor: Indestructible sensor - no costly repairs. No permanent damage from volatile samples.
Standard RS232 output: For data capture via computer. Cable included.
Selectable end-of-measurement alert: Adjustable beeper (continuous, momentary, or off) with flashing LED.
Push-button calibration: Verify calibration easily with KCl Performance Verification Standards.
Intelligent Error Messages: Instrument feedback to keep user informed on performance.
Continuous measurement capability: Useful for time-dependent studies or unusual samples with low water emission.

How Does it Work?

Chilled Mirror Dewpoint Technique
The WP4C measures water potential by determining the relative humidity of the air above a sample in a closed chamber (an AOAC-approved method; also conforms to ASTM 6836). Once the sample comes into equilibrium with the vapor in WP4C's sealed chamber, the instrument finds relative humidity using the chilled mirror method. A tiny mirror in the chamber is chilled until dew just starts to form on it. At the dewpoint, the WP4C measures mirror and sample temperature with 0.001°C accuracy.