FHF05 series
Five models covering the most common heat flux measurement applications
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- thin, flexible and versatile design
- integrated copper spreaders
- waterproof IP67 protection class
- 5 different dimensions and sensitivities
FHF05 series heat flux sensors
Looking to measure heat flux? Start your search with the FHF05 series! These heat flux sensors are available in five different dimensions and sensitivities to suit a wide range of applications. They are flexible, have an integrated temperature sensor, and feature thermal spreaders to reduce thermal conductivity dependence. The rated temperature range is from -70 to +120 °C.
FHF05 sensors measure heat flux from conduction, radiation, and convection. Optional black (BLK) and gold (GLD) stickers are available to separate heat transport by radiation from that by convection. In case FHF05 sensors do not meet your specific requirements, explore our full range of heat flux sensor models for special applications.
Specifications
| measurement range | (-91 to +91) x 10³ W/m² * |
| temperature range: continuous use | -70 to +120 °C |
| temperature sensor | type T thermocouple, IEC 60584-1 Class 2 ** |
| sensor thickness | 0.4 x 10⁻³ m |
| rated bending radius | ≥ 7.5 x 10⁻³ m |
| thermal spreaders | included |
| sensor thermal resistance | 11 x 10⁻⁴ K/(W/m²) |
| outer dimensions (w x b) foil with guard, in 10⁻³ m | (10 x 10), (15 x 30), (50 x 50) , (15 x 85), (85 x 85) |
All specifications
| measurand | heat flux, temperature |
| temperature sensor | type T thermocouple, IEC 60584-1 Class 2 ** |
| thermal spreaders | included |
| rated bending radius | ≥ 7.5 x 10⁻³ m |
| rated load on cable | ≤ 1.6 kg |
| outer dimensions (w x b) foil with guard, in 10⁻³ m | (10 x 10), (15 x 30), (50 x 50) , (15 x 85), (85 x 85) |
| sensor thermal resistance | 11 x 10⁻⁴ K/(W/m²) |
| sensor thickness | 0.4 x 10⁻³ m |
| uncertainty of calibration | ± 5 % (k = 2) |
| measurement range | (-91 to +91) x 10³ W/m² * |
| sensitivity (nominal) per model | |
| – 10X10: | 1 x 10⁻⁶ V/(W/m²) |
| – 15X30: | 3 x 10⁻⁶ V/(W/m²) |
| – 50X50: | 13 x 10⁻⁶ V/(W/m²) |
| – 15X85: | 7 x 10⁻⁶ V/(W/m²) |
| – 85X85: | 50 x 10⁻⁶ V/(W/m²) |
| asymmetry | < 2% |
| temperature range: continuous use | -70 to +120 °C |
| temperature range: short interval use | -160 to +150 °C *** |
| IP protection class | IP67 **** |
| standard cable length | 2 m |
| options | |
| – 5 or 10 m cable length | |
| – seperate cable | |
| – without cable ***** | |
| – BLK black sticker, GLD gold sticker | |
| * with a heatsink temperature of 20 °C, see the user manual for more information. | |
| ** the temperature measurement uncertainty is: ± 1 or 0.0075 × T °C. For details, see the user manual. | |
| *** when measuring at temperatures of < -160 °C, contact Hukx. | |
| **** see appendix on long-term use under condensing, wet and underwater conditions. | |
| ***** sensor foil only (without cable and cable connection block) may be used in vacuum environments. | |
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Have questions or a unique measurement need? Our experts are ready to help you find the perfect solution.
Versatile and suitable for most heat flux measurement applications
FHF05 series heat flux sensors are suitable for general-purpose heat flux measurement. The series consists of sensor models with five different dimensions and sensitivities. Sensors with larger dimensions have a higher sensitivity and a larger area over which the heat flux is averaged.
Thin, flexible, and versatile, FHF05 sensors measure heat flux (in W/m2) either through the object in which they are incorporated or on which they are mounted. Each sensor contains a thermopile that measures the temperature difference across FHF05’s flexible body, which directly translates to heat flux. An integrated Type T thermocouple provides additional temperature measurement. Both the thermopile and thermocouple are passive sensors and do not require external power.
Many competing sensors do not have thermal spreaders, so their sensitivity cannot be relied upon since it varies depending on the material on which they are mounted. The passive guard area around the FHF05 sensor reduces measurement errors due to edge effects and may also be used for mounting.
Using an FHF05 sensor is easy. It connects directly to commonly used data logging systems. The
heat flux (in W/m2) is calculated by dividing FHF05’s output, a small voltage, by the sensitivity, which is provided on its certificate.
Robust and stable
FHF05 has proven to be very robust and stable. The instrument is equipped with a potted cable connection block that prevents moisture from entering and also serves as strain relief.
Unique features and benefits
- flexible (bending radius ≥ 7.5 x 10-3 m)
- low thermal resistance
- wide temperature range
- fast response time
- large guard area
- integrated Type T thermocouple
- robust design, including cable connection block for strain relief
- IP67 protection rating (essential for outdoor and humid environments)
- integrated thermal spreaders for low thermal conductivity dependence
- sensor foil only: may be used in vacuum environments
Suggested use
FHF05 series sensors can be used for general-purpose heat flux measurement and are often applied as part of a larger test or measuring system.
Typical applications per model
- 10X10: high-power microchips
- 15X30: high heat flux in ovens
- 50X50: general-purpose use, battery thermal management
- 15X85: wrapped around a pipe
- 85X85: low heat fluxes, insulation performance testing, use with low-accuracy data loggers and amplifiers
Calibration
FHF05 series’ calibration is traceable to international standards. The factory calibration method follows the recommended practice of ASTM C1130-21.
Installation
There are various ways to install a heat flux sensor. For more information, see our application note on how to install a heat flux sensor.
Options
- with 5 or 10 m cable lengths
- separate cable in 2, 5, or 10 m lengths
- sensor foil only (without wiring and without connection block)
- LI19 hand-held read-out unit/data logger
- NOTE: LI19 measures heat flux only.
- BLK sticker for all models (to measure both radiative and convective heat flux)
- GLD sticker for all models (to measure convective heat flux only)
- BLK and GLD stickers can also be ordered pre-applied at the factory
BLK and GLD stickers
Want to study energy transport/heat flux in more detail? Hukx helps take your measurement to the next level! Order FHF05 series with radiation-absorbing black and radiation-reflecting gold stickers. You can then use one sensor to measure convective + radiative flux and the other to measure convective flux only. Subtract the two measurements to obtain radiative flux.
Stickers are available for every sensor dimension. For instructions, see the BLK – GLD sticker series user manual and installation video.
Optionally, these stickers can be ordered pre-applied on FHF05 series sensors.
Suitable electronics
The combined measurement of heat flux and temperature provides a complete picture of the system’s thermal behavior. Heat flux sensors produce a small millivolt signal output and are often combined with thermocouples as part of a larger test or measuring system. We have several preferred solutions for amplification, data logging, and data visualization. To learn more, view our application notes on sensor amplification or FHF sensors with Hioki data loggers.
Accessories
All accessoriesFrequently Asked Questions
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How to measure heat flux?
Heat flux sensors measure energy flux onto or through a surface in [W/m²].
The source of the heat flux may be:
- conduction
- radiation
- convection
Convective and conductive heat transfer are associated with a temperature difference. Heat always flows from a source to a sink, from a hot to a cold environment. Convective and conductive heat flux is measured by letting this heat flow through the sensor. Radiative flux is measured using heat flux sensors with black absorbers. The absorbers converts radiative to conductive energy. Hukx started in 1993 with sensors for measurement of heat flux in soils and on walls. In the course of the years, we have added specialized sensors and systems for many other applications.
Heat flux sensors manufactured by Hukx are optimized for the demands of different applications:
- rated temperature range
- rated heat flux range
- sensitivity
- response time
- chemical resistance, safety requirements
- size, shape and spectral properties
Hukx is the world market leader in heat flux measurement. We have prepared a white paper briefly explaining the fundamentals of measuring with heat flux sensors. It also offers general directions about what to watch out for and some, perhaps surprising, applications of heat flux sensors. Take a look at our white papers.
What matters most when measuring with a heat flux sensor?
- Representativeness in time and space; average!
A heat flux sensor measures at a certain location. Is this location representative of what you need to measure? If possible, use a relatively large sensor, rather than a small one, and consider use of multiple sensors. Thermal processes often have large time constants; instantaneous measurements may be misleading. Average to get the full picture. - Optical properties
When heat flux sensors also measure radiation, pay attention to the surface color. If needed paint the sensor surface. Please remember that shiny metallic surfaces reflect both infrared and visible radiation. Paints may have different colors in the visible range, but are usually “black” absorbers in the far infrared. - Sensor thermal resistance
A heat flux sensor distorts the local heat flux. In order to minimize this effect, use the sensor with the lowest possible thermal resistance. - Edge effects
A heat flux sensor locally distorts the heat flow pattern, in particular around the edges of the sensor. A passive guard, i.e. a non-sensitive part around the sensor, is essential to avoid errors due to edge effects.
There are more characteristics that matter. Please find them in our white paper on heat flux fundamentals and applications, You may also take a look at our note on How to install a heat flux sensor for tips & tricks.
Which sensor(s) to use for surface energy flux measurement?
Hukx manufactures a range of sensors for surface energy flux measurements. All have proven reliability.
These state-of-the-art sensors are made for the global fluxnet community:
- NR01 is a market leading 4-component net radiometer.
- HFP01 and HFP01SC measure soil heat flux.
- STP01 offers an accurate temperature profile measurement.
- TP01 is the leading sensor for soil thermal conductivity.
Sensors made by Hukx are designed for compatibility with most common data logger models. For many models we have example programs and wiring diagrams available.
How to measure R-value and U-value of buildings?
On-site measurements of thermal resistance, R, are often applied in studies of buildings. Alternatives are to measure its inverse value, the thermal conductance which is called the Λ-value, or the thermal transmittance which includes ambient air boundary layer thermal resistance, the U-value. The measurements of R are based on simultaneous time averaged measurement of heat flux Φ and differential temperature, ΔT, (using two temperature sensors on each on a different side of the wall).
R = ΔT/Φ
Hukx provides a range of sensors and measuring systems for use in measurement of the energy budget of buildings and characterization of construction materials.
HFP01 heat flux sensor and TRSYS20 measuring system are widely used for on-site measurements on walls, windows and other construction elements in building physics.
- HFP01 can be used for in-situ measurement of building envelope thermal resistance (R-value) and thermal transmittance (H-value) according to ISO 9869, ASTM C1046 and ASTM 1155 standards. HFP01 is the world’s most popular sensor for heat flux measurement in the soil as well as through walls and building envelopes. HFP01 measures heat flux through the object in which it is incorporated or on which it is mounted, in W/m². More information? Visit the HFP01 product page.
- TRSYS20 is a high-accuracy system for on-site measurement of thermal resistance, R, thermal conductance, the Λ-value, and thermal transmittance, the U-value, of building envelopes. TRSYS20 is mostly used for measurements according to standard practices of ISO 9869 and ASTM C1155 / C1046. The system is equipped with high-accuracy electronics, two heat flux sensors of model HFP01 as well as two pairs of matched thermocouples. The two measurement locations provide redundancy, leading to a high level of confidence in the measurement result. The high accuracy of the heat flux sensors and temperature difference measurements ensures that TRSYS20 continues measuring when other systems no longer perform, in particular at very low temperature differences across the wall.
Where can I find complete heat flux measuring systems?
Hukx, market leader in heat flux measurement, offers both sensors and systems.
These measuring systems typically include a Measurement and Control Unit and one or more sensors for measuring heat flux as well as other measurands, such as temperature and humidity. Examples are the TCOMSYS01 Hot Cube thermal comfort measuring system, including a TCOM01 sensor, and the TRSYS01 measuring system, incorporating two HFP01 heat flux sensors and two pairs of matched thermocouples.
'Sensors only' can be found here. Complete measuring systems are displayed here, on a separate page.
Cannot find what you are looking for? Please contact us.
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