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FHF05SC series heat flux sensors

Two self-calibrating foil heat flux sensors with thermal spreaders and heater

Available in two models: order the model required for your application!

Next-level sensors from the world market leader in heat flux measurement, FHF05SC series is a combination of our standard models FHF05 heat flux sensor and a heater. The heater allows you to perform self-tests, verifying sensor functionality and stability during use, without having to remove the sensor.  FHF05SC series is ideal for high-accuracy and long-term heat flux measurement, construction of calorimeters, (zero heat flux) core temperature measurement and thermal conductivity test equipment. Available in two models: standard model size 50X50 mm and a larger size of 85X85 mm.

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FHF05SC series  are sensors for general-purpose heat flux measurement, combined with a heater. It is used when the highest level of quality assurance is required and for long-term heat flux measurements. It is thin, flexible and versatile. FHF05SC series measures heat flux through the object in which it is incorporated or on which it is mounted, in W/m2. The sensor within is a thermopile. This thermopile measures the temperature difference across FHF05SC’s flexible body. A type T thermocouple is integrated as well to provide a temperature measurement. The thermopile and thermocouple are passive sensors; they do not require power.

Multiple small thermal spreaders, which form a conductive layer covering the sensor, help reduce the thermal conductivity dependence of the measurement. With its incorporated spreaders, the sensitivity of FHF05SC series is independent of its environment. Many competing sensors do not have thermal spreaders. The passive guard area around the sensor reduces edge effects and is also used for mounting.

Looking only for heat flux and temperature measurement without the heater: see our FHF05 series heat flux sensors.

Unique features and benefits:

  • heater for self-test
  • flexible (bending radius ≥ 15 x 10⁻³ m)
  • low thermal resistance
  • wide temperature range
  • fast response time
  • integrated type T thermocouple
  • robustness, including potted connection block, may be used as strain relief
  • IP protection class: IP67 (essential for outdoor application)
  • integrated thermal spreaders for low thermal conductivity dependence

Using FHF05SC series is easy. For heat flux measurements, it can be connected directly to commonly used data logging systems. The heat flux in W/m2 is calculated by dividing the sensor output, a small voltage, by the sensitivity.

The sensitivity is provided with FHF05SC series on its product certificate. When used under conditions that differ from the calibration reference conditions, the FHF05SC series sensitivity to heat flux may be different than stated on its certificate. See the user manual for suggested solutions.

Make sure your data acquisition accepts type T thermocouples before doing temperature measurements.

Measuring heat flux, users may wish to regularly check their sensor performance. During use, the film heater is activated to perform a self-test.

The heat flux sensor response to the self-test results in a verification of sensor performance.  Implicitly also cable connection, data acquisition, thermal connection of sensor to its environment and data processing are tested. Heat flux sensors are often installed for long periods of time. Using self-testing, the user no longer needs to take sensors to the laboratory to verify their stable performance. In a laboratory environment, using a metal heat sink, you may even perform a formal calibration. The heater has a well characterised and traceable surface area and electrical resistance.

Equipped with a connection block, which may serve as strain relief, and with potted protective covers on both sides so that moisture does not penetrate, FHF05SC series has proven to be very robust and stable.

FHF05SC series calibration is traceable to international standards. The factory calibration method follows the recommended practice of ASTM C1130 – 21.

Requirements for data acquisition and control:

  • for heat flux: one millivolt measurement
  • for heater voltage: one voltage measurement
  • optional, for heater current: one current measurement or voltage measurement over a resistor
  • for switching the heater current on and off: one relay with 12 VDC nominal output
Would you like to study energy transport / heat flux in detail? Hukseflux helps taking your measurement to the next level: order FHF05SC series with radiation-absorbing black and radiation-reflecting gold stickers. You can then measure convective + radiative flux with one, and convective flux only with the other. Subtract the 2 measurements and you have radiative flux. BLK – GLD stickers can be applied by the user to the sensor. There are stickers for every sensor dimension. Optionally,  they can be ordered pre-applied. See the BLK – GLD sticker series user manual and installation video for instructions.


Measurand heat fluxtemperature
Outer dimensions foil with guard (50 x 50, 85 x 85) x 10⁻³ m
Measurement range (-10 to +10) x 10³ W/m²
Sensitivity (nominal) :
13 x 10⁻⁶ V/(W/m²)
50 x 10⁻⁶ V/(W/m²)
Temperature sensor type T thermocouple, IEC 60584-1:2013 class 2*
Thermal spreaders included
Rated bending radius ≥ 15 x 10⁻³ m
Rated load on cable ≤ 1.6 kg
Sensor thermal resistance 24 x 10⁻⁴ K/(W/m²)
Sensor thickness 0.7 x 10⁻³ m
Uncertainty of calibration ± 5 % (k = 2)
Rated temperature range – continuous use -40 to +120 °C**
Rated temperature range – short intervals -160 to +150 °C**
IP protection class IP67***
Standard wire length 2 m
Heater resistance per model :
FHF05SC-50X50 120 Ω (nominal)
FHF05SC-85X85 40 Ω (nominal)
Heater power supply 12 VDC
Options 5 or 10 m cable length, separate cable, BLK black sticker, GLD gold sticker
* temperature measurement uncertainty: 5 % of value in C. For details, refer to user manual.
** rated operating conditions: 120 ˚C continuous use, 150 ˚C short intervals; use to -80 ˚C is possible.
sensor is not suitable for continuous exposure to water.
  • with 5 or 10 metres cable length
  • separate cable in 2, 5 or 10 metres length
  • LI19 hand-held read-out unit / datalogger
    NOTE: LI19 measures heat flux only, not temperature, does not support the self-test functionality
  • BLK black sticker (to measure radiative
    as well as convective heat flux)
  • GLD gold sticker (to measure convective heat flux only)
  • BLK – GLD sticker series can also be ordered pre-applied at the factory


Suggested use

  • high-accuracy scientific measurement of heat flux, with a high level of data quality assurance
  • study of convective heat transfer mechanisms
  • calorimeter prototyping
  • (zero heat flux) non-invasive core temperature measurement
  • thermal conductivity test equipment
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