Thermoelectric heat flux sensor FHF05SC

with auto-calibrationR&Dthin-film

Overview
The FHF05SC series are self-calibrating, flexible foil heat flux sensors with integrated heaters and thermal spreaders, designed for high-accuracy, long-term heat flux measurement and in-situ self-testing. Two sizes are available: 50 × 50 mm (standard) and 85 × 85 mm (larger, more sensitive).

Key features and benefits

• Self-calibrating design with integrated heater enabling online functionality testing and self-test/self-calibration without sensor removal.
• Integrated heater for self-testing (requires power when activated).
• Thin, flexible foil construction (rated bending radius ≥ 15 × 10⁻³ m) for versatile mounting and low thermal disturbance.
• Incorporated thermal spreaders to reduce sensitivity dependence on the thermal properties of the mounting substrate.
• Integrated Type T thermocouple (IEC 60584-1 Class 2*) for temperature measurement in addition to the thermopile heat flux measurement.
• Robust design with potted cable connection block for strain relief and moisture protection; IP67 rated for protection in outdoor and humid environments.
• Low sensor thermal resistance and fast response time, suitable for high-accuracy scientific applications and long-term monitoring.

Applications & usage notes

• High-accuracy scientific measurement of heat flux (W/m²), calorimeter prototyping, thermal conductivity testing, and (zero heat flux) core temperature measurement.
• To obtain heat flux (W/m²), divide the sensor output voltage by the sensor sensitivity given on the product certificate; sensitivity can vary if measurement conditions differ from calibration reference conditions.
• Ensure your data acquisition supports millivolt-level measurements for heat flux and Type T thermocouples for temperature; see measurement & control requirements below.

Measurement & control requirements

• Heat flux: one millivolt measurement channel (high resolution).
• Heater voltage: one voltage measurement channel (12 VDC nominal heater supply).
• Optional heater current: one current measurement or voltage-over-resistor measurement for power monitoring.
• Heater switching: one relay or switch with 12 VDC nominal output to switch heater current on/off.
• Temperature: Type T thermocouple input for the integrated thermocouple.

Technical specifications

• Measurand: heat flux (and temperature via Type T thermocouple).
• Temperature sensor: Type T thermocouple, IEC 60584-1 Class 2*.
• Thermal spreaders: included (multiple small spreaders forming a conductive layer).
• Online functionality testing: self-test including self-calibration via integrated heater.
• Rated bending radius: ≥ 15 × 10⁻³ m.
• Rated load on cable: ≤ 1.6 kg.
• Outer dimensions (foil with guard): (50 × 50) × 10⁻³ m and (85 × 85) × 10⁻³ m.
• Sensor thermal resistance: 24 × 10⁻⁴ K/(W/m²).
• Sensor thickness: 0.7 × 10⁻³ m.
• Uncertainty of calibration: ± 5 % (k = 2).
• Measurement range: (-10 to +10) × 10³ W/m².
• Sensitivity (nominal): 50×50: 13 × 10⁻⁶ V/(W/m²); 85×85: 50 × 10⁻⁶ V/(W/m²).
• Rated temperature range (continuous use): -40 to +120 °C**.
• Rated temperature range (short intervals): -160 to +150 °C** (for -160 °C contact Hukx per manual).
• IP protection class: IP67***.
• Standard wire length: 2 m (options available: 5 or 10 m cable length without cable block).
• Heater resistance (nominal): 50×50: 120 Ω; 85×85: 40 Ω.
• Heater power supply: 12 VDC nominal.
• Options: 5 or 10 m cable length (sensor foil only may be used in vacuum without cable and connection block), BLK (black) sticker, GLD (gold) sticker; stickers can be used to measure radiative vs convective flux (BLK/GLD method).
• Notes: *Temperature measurement uncertainty: ±1 °C or 0.0075 × T °C (see user manual). **When measuring at extreme temperatures (e.g. -160 °C) consult the manufacturer/user manual. ***See appendix regarding long-term use under condensing, wet, and underwater conditions.