The HFP01SC, manufactured by Hukseflux, measures soil heat flux, typically for energy-balance in flux systems. It is intended for applications requiring the highest possible degree of measurement accuracy. At least two sensors are required for each site to provide spatial averaging. Sites with heterogeneous media may require additional sensors.
Read MoreThe HFP01SC consists of a thermopile and a film heater. The thermopile measures temperature gradients across the plate. During the in-situ field calibration, the film heater is used to generate a heat flux through the plate. The amount of power used to generate the calibration heat flux is measured by the datalogger. Each plate is individually calibrated, at the factory, to output flux.
Self-calibration corrects for errors due to differences in thermal conductivity between the sensor and surrounding medium, temperature variations, and slight sensor instabilities.
Sensor Type | Thermopile with film heater |
Sensitivity | 50 μV W-1 m-2 (nominal) |
Nominal Resistance | 2 Ω |
Temperature Range | -30° to +70°C |
Expected Typical Accuracy | ±3% of reading |
Heater Resistance | 100 Ω (nominal) |
Heater Voltage Input | 9 to 15 Vdc |
Heater Voltage Output | 0 to 2 Vdc |
Duration of Calibration | ±3 minutes @ 1.5 W (typically performed every 3 to 6 hours) |
Average Power Consumption | 0.02 to 0.04 W |
Plate Diameter | 80 mm (3.15 in.) |
Plate Thickness | 5 mm (0.20 in.) |
Weight | 200 g (7.05 oz) without cable |
CR1000X program that measures the HFP01SC, performs the self-calibration, and checks for calibration validity. Refer to the manual for the equations used for the self-calibration and calibration-validity checks. A table in the manual provides a cross reference of the terms in the equations in the manual with the constants and variables in the example data logger program.