HFP01SC self-calibrating heat flux sensor™ is a heat flux sensor for use in the soil. It offers the best available accuracy and quality assurance of the measurement. The on-line self-test verifies the stable performance and good thermal contact of sensors that are buried and cannot be visually inspected and taken to the laboratory for recalibration. The self-test also includes self-calibration which compensates for measurement errors caused by the thermal conductivity of the surrounding soil (which varies with soil moisture content), for sensor non-stability and for temperature dependence.
HFP01SC measures soil heat flux in W/m². It is used when the highest level of quality assurance and a high measurement accuracy are required. In essence, HFP01SC is a combination of a heat flux sensor and a film heater. The heat flux sensor output is a voltage signal that is proportional heat flux through the sensor. At a regular interval the film heater is activated to perform a self-test. The self-test results in a verification of sensor contact to the soil and in a new sensitivity that is valid for the circumstances at that moment. The latter is called self-calibration. Implicitly also cable connection, data acquisition and data processing are tested. The result is a much improved accuracy & quality assurance of the measurement relative to measurements with conventional sensors such as model HFP01.
Measurand: | heat flux |
Measurement Range: | -2000 to +2000 W/m² |
Sensitivity (nominal): | 60 x10⁻⁶ V/(W/m)² |
On-line functionality testing: | self-test including self-calibration |
Sensing area: | 8 x10⁻⁴ m² |
Sensor thermal resistance: | 81 x10⁻⁴ K/(W/m²) |
Rated operating temperature range: | -30 to +70°C |
IP protection class: | IP67 |
Film heater resistance: | 100 Ω ±10% |
Film heater rated power supply: | 9 to 15 VDC |
Interval between self-tests: | 6 hr |
Heating interval duration: | 180 s |
Power consumption daily average: | 0.02 W |
Standard cable length: | 2 x 5 m |
Options: | longer cable length (10, 15, 20, 30, 40 m) |