Hukseflux FHF05 Series User manual

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USER MANUAL
FHF05 series
Foil heat flux sensors with thermal spreaders, flexible,
5 different dimensions and sensitivities, with temperature
sensor

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Cautionary statements
Cautionary statements are subdivided into four categories: danger, warning, caution and
notice according to the severity of the risk.
DANGER
Failure to comply with a danger statement will lead to death or serious
physical injuries.
WARNING
Failure to comply with a warning statement may lead to risk of death or
serious physical injuries.
CAUTION
Failure to comply with a caution statement may lead to risk of minor or
moderate physical injuries.
NOTICE
Failure to comply with a notice may lead to damage to equipment or may
compromise reliable operation of the instrument.

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Contents
Cautionary statements 2
Contents 3
List of symbols 4
Introduction 5
1Ordering and checking at delivery 8
1.1 Ordering FHF05 8
1.2 Included items 8
1.3 Quick instrument check 9
2Instrument principle and theory 11
3Specifications of FHF05 series 14
3.1 Specifications of FHF05 series 14
3.2 Dimensions of FHF05 series 18
4Standards and recommended practices for use 20
4.1 Heat flux measurement in industry 20
5Installation of FHF05 series 21
5.1 Site selection and installation 21
5.2 Installation on curved surfaces 23
5.3 Electrical connection 24
5.4Requirements for data acquisition / amplification 27
6Maintenance and trouble shooting 28
6.1 Recommended maintenance and quality assurance 28
6.2 Trouble shooting 29
6.3 Calibration and checks in the field 30
7Appendices 32
7.1 Appendix on cable and wire extension 32
7.2 Appendix on installation of FHF05 sensor foil 33
7.3 Appendix on using FHF05 series with BLK –GLD sticker series 36
7.4 Appendix on standards for calibration 37
7.5 Appendix on calibration hierarchy 38
7.6 Appendix on correction for temperature dependence 38
7.7 Appendix on measurement range for different temperatures 39
7.8 Appendix on temperature measurement accuracy 40
7.9 EU declaration of conformity 42

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List of symbols
Quantities Symbol Unit
Heat flux ΦW/m²
Voltage output U V
Sensitivity S V/(W/m2)
Temperature T °C
Thermal resistance per unit area Rthermal,A K/(W/m²)
subscripts
property of heatsink heatsink
maximum value, specification limit maximum

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Introduction
FHF05 series are the latest standard model for general-purpose heat flux measurement.
Models are available in five dimensions and sensitivities. Significantly thinner and more
flexible, FHF05 series replaces earlier models FHF01 to FHF04. All FHF05 models are very
versatile: they have an integrated temperature sensor and thermal spreaders to reduce
thermal conductivity dependence. It is applicable over a temperature range from –70 to
+120 °C. FHF05 series measures heat flux from conduction, radiation and convection.
Optionally, black BLK and gold GLD stickers are available for every sensor model to
separately determine heat transport by radiation and convection.
All FHF05’s measure heat flux through the object in which it is incorporated or on which it
is mounted, in W/m2. The sensor in FHF05 is a thermopile. This thermopile measures the
temperature difference across FHF05’s flexible body. A type T thermocouple is integrated
as well. 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 FHF05 is independent of its environment. Many
competing sensors do not have thermal spreaders. The passive guard area around the
sensor reduces measurement errors due to edge effects and is also used for mounting.
Figure 0.1 Model FHF05-50X50 foil heat flux sensor with thermal spreaders: thin, flexible
and versatile
Using FHF05 series is easy. It can be connected directly to commonly used data logging
systems. The heat flux in W/m2is calculated by dividing the FHF05 output, a small voltage,
by the sensitivity. The sensitivity is provided with FHF05 on its product certificate.
All FHF05’s have unique features and benefits:

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•flexible (bending radius ≥ 7.5 x 10-3 m)
•low thermal resistance
•wide temperature range
•fast response time
•large guard area
•integrated thermal spreaders for low thermal conductivity dependence
•integrated type T thermocouple
•robustness, including cable and connection block which may be used as strain relief
between sensor and cable
•IP protection class: IP67 (essential for outdoor application)
Equipped with a protective potted connection block, which may serve as strain relief so
that moisture does not penetrate, FHF05 has proven to be very robust and stable.
Figure 0.2 Model FHF05-15X85 foil heat flux sensor being installed to measure heat flux
on a pipe
FHF05 has calibration that is traceable to international standards. The factory calibration
method follows the recommended practice of ASTM C1130 - 21. When used under
conditions that differ from the calibration reference conditions, the sensitivity of the
FHF05 series to heat flux may be different than stated on its certificate. See Chapter 2 in
this manual for best practices.
Would you like to study energy transport / heat flux in detail? Hukseflux helps taking this
measurement to the next level: order FHF05 series with radiation-absorbing black BLK and
radiation-reflecting gold GLD stickers. You can then measure convective + radiative flux
with one, and convective flux only with the other. Subtract the two measurements and you
have radiative flux. They can be applied to the sensor by the user or ordered pre-applied
at the factory; see the BLK –GLD sticker series user manual and installation video for
instructions. Stickers are avaible for every sensor model.

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Figure 0.3 Model FHF05-50X50 heat flux sensor: with BLK-50X50 and GLD-50X50
stickers
See also:
•FHF05SC series for a self-calibrating version of FHF05
•heater HTR02 series, for calibration and verification of performance of FHF-type
sensors
•model HFP01 for increased sensitivity (also consider putting two or more FHF05’s in
series)
•BLK - GLD sticker series for every sensor dimension to separate radiative and
convective heat fluxes
•Hukseflux offers a complete range of heat flux sensors with the highest quality for
any budget

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1Ordering and checking at delivery
1.1 Ordering FHF05
The standard configuration of FHF05 series is FHF05-50X05-02, model 50X50 with 2
metres of cable. Common options are:
•model FHF05-10X10
•model FHF05-15X30
•model FHF05-15X85
•model FHF05-85X85
•change -02 to -05 or -10 metres for the respective cable length
•without wiring, without connection block
•with a separate cable in 2, 5, or 10 metres cable length
•with LI19 hand-held read-out unit / datalogger; NOTE: LI19 measures heat flux only,
not temperature
•with HTR02 series, a foil heater of calibration and verification of performance
•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 for every
sensor dimension
1.2 Included items
Arriving at the customer, the delivery should include:
•heat flux sensor FHF05 with wires of the length as ordered
•product certificate matching the instrument serial number

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Figure 1.2.1 Model FHF05-50X50 with serial number and sensitivity shown at the end of
the cable
1.3 Quick instrument check
A quick test of the instrument can be done by connecting it to a multimeter.
1. Check the sensor serial number and sensitivity on the label at the end of FHF05’s cable
against the product certificate provided with the sensor.
2. Inspect the instrument for any damage.
3. Check the electrical resistance of the sensor between the red [+] and black [-] wires.
Use a multimeter at the 1k Ω range. Measure the sensor resistance first with one
polarity, then reverse the polarity. Take the average value. The typical resistance of the
wiring is 0.3 Ω/m. Typical resistance should be the nominal sensor resistance mentioned
in table 3.1.1 plus 0.6 Ω for the total resistance of two wires for each metre (back and
forth). Infinite resistance indicates a broken circuit; zero or a lower than 1 Ω resistance
indicates a short circuit.
4. Check the electrical resistance of the thermocouple between the brown [+] and white
[-] wires. Use a multimeter at the 100 Ω range. Measure the thermocouple resistance
first with one polarity, then reverse the polarity. Take the average value. The typical
resistance of the copper wiring is 0.3 Ω/m, for the constantan wiring this is 6.5 Ω/m.
Typical resistance should be the nominal thermocouple resistance of 2.5 Ω plus 6.8 Ωfor
the total resistance of the two wires of each metre (back and forth). Infinite resistance
indicates a broken circuit; zero or a lower than 1 Ω resistance indicates a short circuit.

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5. Check if the sensor reacts to heat: put the multimeter at its most sensitive range of
DC voltage measurement, typically the 100 x 10-3 VDC range or lower. Expose the sensor
to heat. Exposing the back side (the side without the dot) to heat should generate a
positive signal between the red [+] and black [-] wires. Doing the same at the front side
(the side with the dot), reverses the sign of the output.