WP4

Measure water potential with the WP4 Dewpoint Meters

Measuring water potential using a pressure plate or filter paper is imprecise and can take several weeks. The WP4 and WP4-T measure water potential in less than 5 minutes from 0 to –300 MPa with a resolution of 0.1 MPa. Using the AOAC-approved Chilled Mirror Dewpoint Technique, the WP4 measures water potential by determining the relative humidity of the air above the sample in a closed chamber (at temperature equilibrium, relative humidity is a direct measurement of water potential). The instrument is easy to use and maintain, and calibration is simple.

WP4-T with Internal Temperature Control

The WP4-T features internal temperature control. Water potential mesurements are temperature sensitive: if the lab temperature fluctuates ±5°C, water potential readings can vary as much as ±0.5 MPa. The WP4-T enables you to eliminate the effect of ambient temperature fluctuations.

Other applications of internal temperature control:

to study effects of temperature on water potential.
sample-to-sample comparison of water potential independent of temperature.

Features

The WP4 is a bench-top enclosure with an integral sensor drawer. To initiate a reading, simply close the sample drawer. You can transfer your soil suction data to a computer or printer with the included serial RS232 interface cable. Additional features include: Easy-to-clean, durable one-piece sensor.

Push-button calibration using performance verification standards.
Continuous measurement mode (for time-dependent studies or samples with low water emission).
Intelligent error messages to keep you informed of instrument performance.

Benefits

Unparalleled accuracy.
Speed: 5 minutes per sample.
1 year warranty on parts and labor.
Auto-ranging: Up to 50% faster speed at all soil suction levels.
No tool maintenance: Thumb-screws secure lid and sensor plate.

Each WP4 and WP4-T is shipped with:
user manual, cleaning kit, 12 KCl verification standards, 100 sample cups and lids, an RS232 serial cable, and a power cord.

Specifications:

Operating Enviroment:
5 to 43°C (41 to 110° F)
Interface Cable:
Standard RS232 serial cable (included)
Temperature Control (WP4-T only):
15° to 40° C (±0.2 °C)
Data Communications:
RS232 compatible, 8 data bit ASCII code, 9600 baud, no parity, 1 stop bit
Sensors:
1. Infrared temperature sensor
2. Chilled-mirror dewpoint sensor
Weight:
3.2 kg (5.2 kg shipping weight)
Universal Power:
110V to 220V AC, 50/60Hz
Warranty:
1 year, parts and labor

Display:
20 x 2 alphanumeric dot-matrix LCD with backlighting.
Case material:
Powder-painted aluminum
Range:
0 to -300 MPa
Sample dish capacity:
7ml recommended (15ml full)
Accuracy:
±0.1 MPa from 0 to -10MPa
±1% from -10 to -300 MPa
Enclosure size:
24.1 x 22.9 x 8.9cm (9.5 x 9.0 x 3.5in)
Read time:
~5 minutes for most soil samples
~20 minutes for plant tissue samples

For additional technical information and users manual see:
http://www.decagon.com/environmental/wp4