The 229-L Water Matric Potential Sensor measures soil water potential from 0.1 to 10 bars. The sensor consists of a heating element and thermocouple emplaced in epoxy in a hypodermic needle, which is encased in a porous ceramic matrix. To calculate soil water matric potential, a Current Excitation Module applies a 50 mA current to the 229's heating element, and the 229 thermocouple measures the temperature rise. The magnitude of the temperature rise varies according to the amount of water in the porous ceramic matrix, which changes as the surrounding soil wets and dries. Soil water matric potential is determined by applying a second-order polynomial equation to the temperature rise. Users must individually calibrate each of their 229 sensors in the soil type in which the sensors will reside. Features Uses heat dissipation method for soil water matric potential measurementMeasurement time is 30 secondsCE8 8-Channel or CE4 4-Channel 50 mA Constant Current Source used with heating element for heat sourceRequires individual calibration Specifications Measurement Range: -10 to -2500 kPa Measurement Time: 30 seconds typical Thermocouple Type: copperconstantan (type T) Heater Resistance: 34 ohms Resolution: 1 kPa at matric potentials greater than -100 kPa
Beijing, China
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Jack (Beijing Channel Scientific Instruments Co.,Ltd.)
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