HFP01SC-L Hukseflux Self-Calibrating Soil Heat Flux Plate

Categories Soil , In-Situ Soil Physical Research

The HFP01SC, manufactured by Hukseflux, measures soil heat flux—typically for energy-balance or Bowen-ratio flux systems. It is intended for applications requiring the highest possible degree of measurement accuracy. The HFP01SC outputs a voltage signal that is proportional to the heat flux of the surrounding medium. At least two sensors are required for each site to provide spatial averaging. Sites with heterogeneous media may require additional sensors.

The 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 data logger. 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.

Note: In an energy-balance installation, all sensors must be completely inserted into the soil face before the hole is backfilled.

Overview
Specification

Campbell Scientific HFP01SC-L Hukseflux Self-Calibrating Soil Heat Flux Plate typically used in Bowen ratio and energy balance systems
Voltage output proportional to local heat flux
The on-board heater allows calibration via the "Van den Bos-Hoeksema" method
Calibration takes 8 minutes; typically performed every three hours
Minimum of two soil heat flux measurements are recommended for a homogeneous site
Manufactured by Hukseflux

Benefits and Features

Corrects for errors due to differences in thermal conductivity between the sensor and surrounding medium, temperature variations, and slight sensor instabilities
Compatible with most Campbell Scientific data loggers
Uses Van den Bos-Hoeksma self-calibration method to provide a high degree of measurement accuracy

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