Campbell Scientific HFT3 REBS Soil Heat Flux Plate - Manual (Page 5)

1
Model HFT3 Soil Heat Flux Plate
1. General Description
The HFT3 Soil Heat Flux plate uses a thermopile to measure temperature
gradients across the plate. Each plate is individually calibrated to output flux.
In order to measure soil heat flux at the surface, several HFT3s are used to
measure the soil heat flux at a depth of eight cm. A TCAV Averaging Soil
Thermocouple is used to measure the temporal change in temperature of the
soil layer above the HFT3. Finally, a CS615 Water Content Reflectometer is
used to measure the soil water content. The temporal change in soil
temperature and soil water content are used to compute the soil storage term.
The -L option on the model HFT3 Soil Heat Flux plate (HFT3-L) indicates that
the cable length is user specified. This manual refers to the sensor as the
HFT3.
2. Specifications
Operating Temperature: -40
°C to +55°C
Storage Temperature: -40
°C to +55°C
Plate Thickness: 3.91 mm (0.154 in.)
Plate Diameter: 38.2 mm (1.5 in.)
Sensor: thermopile
Measurement Range:
±100 W m -2
Signal Range:
±2.4 mV for the above range
Accuracy: better than
±5% of reading
Thermal Conductivity: 1.22 W m
-1
K
-1