Hukseflux

Thermal Sensors

USER MANUALHTR02 series
Heater for calibration and verification of
performance of FHF-type heat flux sensors

Copyright by Hukseflux | HTR02 series manual v2204 |www.hukseflux.com| info@hukseflux.com

Warning statements
Cautionary statements are subdivided into four categories: danger, warning, caution andnotice 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 orserious physical injuries.

CAUTION
Failure to comply with a caution statement may lead to risk of minor ormoderate physical injuries.

NOTICE
Failure to comply with a notice may lead to damage to equipment or may
compromise reliable operation of the instrument.

H TR 0 2 s e ri e s man u a l v 220 4

2/ 26

Contents
Warning statements
Contents
List of symbols
Introduction
1
Ordering and checking at delivery
1.1
Ordering HTR02
1.2
Included items
1.3
Quick instrument check2
Instrument principle and theory
2.1
Basic operation
2.2
A self-test for heat flux sensors
2.3
Using heaters with FHF05 series
2.4
Calibrating heat flux sensors
2.5
An in-situ test for heat flux sensors
3
Specifications of HTR02 series
3.1
Specifications of HTR02 series
3.2
Dimensions of HTR02 series
4
Installation of HTR02 series
4.1
Site selection and installation
4.2
Electrical connection
5
Maintenance and trouble shooting
5.1
Recommended maintenance and quality assurance
5.2
Trouble shooting
5.3
Calibration and checks in the field
6
Appendices6.1
EU declaration of conformity

H TR 0 2 s e ri e s man u a l v 220 4

2
3
4
5
7
7
7
8
9
9
9
10
12
13
16
16
18
19
19
21
23
23
24
24
25
25

3/ 26

List of symbols
Quantities

SymbolUnit

Heat flux
Voltage
Sensitivity
Temperature
Thermal resistance per unit area
Area
Electrical resistanceElectrical power

ΦUS
T
Rthermal,A
A
R
P

W/m²
V
V/(W/m2)°C
K/(W/m²)
m2Ω
W

Subscripts
Property of heatsink
Property of heater
Property of sensor
Maximum value, specification limit

H TR 0 2 s e ri e s man u a l v 220 4

heatsink
heatersensormaximum

4/ 26

Introduction
HTR02 series are heaters that can be used for calibration and functionality checks of FHFtype heat flux sensors like FHF05 series. The heaters have a 4-wire connection with aknown surface area and electrical resistance. Users can now easily and objectively checktheir sensor performance before and after use. HTR02 series is available in two different
models: 50 x 50 and 85 x 85 mm. See also FHF05SC series heat flux sensor withintegrated heater.
Measuring heat flux, users may wish to regularly check their sensor performance. A quick
check or a formal calibration is now possible with HTR02 series plus some accessories
that most laboratories will have in-house. The HTR02 series heaters have a wellcharacterised traceable surface area and electrical resistance.
In a typical test setup, the heat losses through the insulation are typically smaller than 3% and may be ignored. Measuring the heater power (voltage Uheater squared divided byresistance Rheater), and dividing by the surface area Aheater, gives the applied heat flux.
The heat flux sensor sensitivity S is the voltage output Usensor divided by the applied heatflux.
S = (Usensor∙Rheater∙Aheater)/Uheater²(Formula 0.1)

The reproducibility of this test is much improved when using contact material between
heater, sensor and heat sink.
HTR02 series has unique features and benefits:•
makes it possible to perform a simple test•
guarantees sensor stability•
matches FHF05 series heat flux sensors

Figure 0.1 On the left model HTR02-85X85 heater for calibration and verification of
performance of the models of FHF05 series heat flux sensors, on the right model FHF0585X85 to which HTR02-85X85 may be applied. See also figure 3.2.1 for dimensions.

H TR 0 2 s e ri e s man u a l v 220 4

5/ 26

HTR02 series is a foil heater and comes in two models. Either it can be used in
combination with foil heat flux sensors such as FHF05 series for test and calibration
purposes, or it can be used as a general-purpose heater.
Options:••

available with standard cable length -02 metre, or change -02 to -05 or -10 metresfor the respective cable length
cables can also be ordered separately in 2, 5 or 10 metres length

See also:•••

FHF05SC heat flux sensor with integrated heater
FHF05 series general purpose heat flux sensor
view our complete range of heat flux sensors

H TR 0 2 s e ri e s man u a l v 220 4

6/ 26

1

Ordering and checking at delivery

1.1 Ordering HTR02
The standard configuration of HTR02 series is model 50X50 with 2 metres of cable, ordercode: HTR02-50X50-02.
Common options are:•••model HTR02-85X85-05 or -10 metres cable lengthwith a separate cable in 2, 5 or 10 metres cable length

1.2 Included items
Arriving at the customer, the delivery should include:••

HTR02 heater with cable of the length as ordered
product certificate matching the instrument serial number

Figure 1.2.1 Model HTR02-50X50 with serial number and resistance shown at the end of
the cable.

H TR 0 2 s e ri e s man u a l v 220 4

7/ 26

1.3 Quick instrument check
A quick test of the instrument can be done by connecting it to a multimeter:
1. Check the heater serial number on the label at the end of HTR02’s cable against the
product certificate provided with the heater.
2. Inspect the instrument for any damage.
3. Check the electrical resistance of the heater between any of the yellow wires and anyof the grey wires. Use a multimeter at the 1 kΩ range. Typical resistance should bearound 120 Ω for model -50X50 and around 40 Ω for model -85X85. Infinite
resistance indicates a broken circuit; zero or a lower than 1 Ω resistance indicates ashort circuit.
4. Check the electrical resistance between the 2 yellow wires. These resistances should
be in the 0.1 Ω/m range, so 0.2 Ω in case of the standard 2 m wire length. Higher
resistances indicate a broken circuit. Repeat this measurement for the 2 grey wires.

H TR 0 2 s e ri e s man u a l v 220 4

8/ 26

2

Instrument principle and theory

HTR02 series is a foil heater. Either it can be used in combination with foil heat flux
sensors such as FHF05 series for test and calibration purposes, or it can be used as a
general-purpose heater.

2.1 Basic operation
If a voltage Uheater is applied to the heater such that an electrical current Iheater runs
through the heater, the heater power Pheater may be calculated as:
Pheater = Uheater∙Iheater = Uheater2/Rheater = Iheater2∙Rheater
where Rheater is the heater electrical resistance. If the heater is placed in a uniform
environment (i.e., same medium on both sides of the heater) the applied heat flux Φ ineither direction may be calculated as:Φ = Pheater/(2·Aheater)(Formula 2.1.1)

where Aheater is the heater area. If, however, the heater is placed in between a thermal
insulator and a good thermal conductor the heat flux Φ in the direction of the conductoris:Φ = Pheater/Aheater(Formula 2.1.2)

Other cases exist as well. Users need to evaluate which case applies to their situation.

2.2 A self-test for heat flux sensors
In combination with a heat flux sensor such as FHF05 series, HTR02 can be used to test
the response of the heat flux sensor. To this end HTR02 should be positioned directly on
top of the heat flux sensor such that HTR02 can be used to apply a heat flux through theheat flux sensor.
A self-test is started by switching on HTR02, while recording the heat flux sensor output
signal and the HTR02 heater power and finalised by switching HTR02 off. During theheating interval, Iheater is fed through the foil heater which generates a heat flux
proportional to the heater power. Pheater can be measured in several different ways:•

heater voltage and current, Pheater = Uheater∙Iheater(Formula 2.2.1)•

heater voltage and known heater resistance, Pheater = Uheater2/Rheater(Formula 2.2.2)•

heater current and known heater resistance, Pheater = Iheater2∙Rheater(Formula 2.2.3)

If performed in a four-wire configuration the first method is preferred because it isgenerally more accurate than the latter two methods, however it requires both avoltmeter and an ammeter instead of just one of the two.

H TR 0 2 s e ri e s man u a l v 220 4

9/ 26

Analysis of the heat flux sensor response to the heating (the self-test) serves several
purposes:•••

first, the amplitude and response time under comparable conditions are indicators of
the sensor stability. See 2.5 for application examples.
second, the functionality of the complete measuring system is verified. For example:
a broken cable is immediately detected.
third, under the right conditions, after taking the sensor out of its normal
environment, the self-test may be used as calibration. See 2.4 for more details.
Compatible compatible

2.3 Using heaters with FHF05 series
HTR02 series is compatible with the models from the FHF05 series. Model FHF05-50X50
and -85X85 fit directly with HTR02-50X50 and -85X85 respectively.
Models FHF05-10X10 and FHF05-15X30 fit with HTR02-50X50. Model FHF05-15X85 canbe used with HTR02-85X85. Because in these cases the heater is larger than the sensor,
it is recommended to make a guard when using these models with HTR02. See table
2.3.1 for an overview of the models and suggested heaters.

Figure 2.3.1 Using heater model HTR02-50X50 with heat flux sensor FHF05-15X30.
A plastic guard is made with help of a 3D-printer.
To get a representative measurement, the heater should ‘see’ the same environment.
Surrounded by a material like a metal heat sink, the sensor will locally increase thethermal resistance. The heat from the heater will follow the easiest path; in the case theheater is larger than the sensor, flow to the metal heat sink. Therefore, the sensor willmeasure an underestimation of the actual heat flux.

H TR 0 2 s e ri e s man u a l v 220 4

10/26

Figure 2.3.2 Using HTR02 series heaters with FHF05 series. FHF05 models -10X10 ans 15X30 are compatible with HTR02-50X50. Model FHF05-15X85 is compatible with HTR0285X85. We recommend making a guard around the sensor with equal thermal resistanceand thickness. The orange-coloured part is the area where we recommend making aguard.
To create an environment with constant thermal resistance, make a guard around thesensor with equal thermal resistance and thickness. FHF05 series have a thermal
resistance of Rthermal = 11 × 10-4 K/(W/m²) and a thickness of 0.4 × 10-3 m.
We recommend a guard made from plastic. Most plastics have a thermal resistance in thesame order of magnitude as the base material of the sensor. Use tape of comparable
thickness or print a guard with a 3D printer. See figure 2.3.1.
Table 2.3.1 Suggested use of FHF05 series with HTR02 series.
MODEL FHF05

SUGGESTED HTR02 MODEL

GUARD RECOMMENDED?

FHF05-10X10
FHF05-15X30
FHF05-50X50
FHF05-15X85
FHF05-85X85

HTR02-50X50
HTR02-50X50
HTR02-50X50
HTR02-85X85
HTR02-85X85

yes
yes
no
yes
no

H TR 0 2 s e ri e s man u a l v 220 4

11/26

2.4 Calibrating heat flux sensors
It is recommended to recalibrate heat flux sensors at least once every two years. HTR02
series can be used to calibrate heat flux sensors such as the models in the FHF05 series.
In a typical calibration setup as shown in figure 2.4.1, a stack is made of a heatsink, theheat flux sensor to be calibrated, the heater and an insulating material. In such a setup,the heat losses through the insulation is for FHF-type sensors in the order of magnitudeof 3 %. In this case heat generated by HTR02 flows through the heat flux sensor to theheat sink. Measuring the heater power Pheater, and dividing by the surface area Aheater,
gives the applied heat flux:Φ = Pheater/Aheater(Formula 2.3.1)

The heat flux sensor sensitivity S is the voltage output of the sensor Usensor divided by theapplied heat flux Φ:
S = Usensor/Φ

(Formula 2.3.2)

The reproducibility of this test is much improved when using contact material (such as
glycerol or a thermal paste) between heater, sensor and heat sink.

Figure 2.4.1 Calibration of a heat flux sensor; a typical stack used for calibrationconsists of a block of metal (mass > 1 kg), for example aluminium (5), the heat flux
sensor (3), HTR02 (2) and an insulation foam (1). Under these conditions, heat losses
through the insulation are negligible. Heat flux (4) flows from hot to cold.

H TR 0 2 s e ri e s man u a l v 220 4

12/26

2.5 An in-situ test for heat flux sensors
The HTR02 series heater can be used to test the stable performance of the heat flux
sensors such as FHF05 series.
HTR02 series should be installed on top of the heat flux sensor, preferably on the side of
the heat flux sensors with the more insulating medium. In case the heater is used for
repeated verifications at one location, consider using our FHF05SC series: sensor with a
HTR02 heater integrated.
A typical stability check is performed based on the step response of the measured heat
flux and sensor temperature to a heat flux applied by HTR02. Upon installing the heat
flux sensor and HTR02, a reference measurement should be made. A time trace of theheater power, the measured heat flux and the measured sensor temperature should be
stored as reference data. Stable operation of the heat flux sensor can then be confirmed
at any time by comparing to the reference measurement. The test protocol consists ofthe following steps:
1. Make sure that the absolute temperature is similar to that during the reference
measurement.
2. Check the heater resistance stability. This can be done accurately by using the four
heater wires to conduct a four-point resistance measurement.
3. Record a time trace of the heater power, the measured heat flux and the sensor
temperature; the same parameters as in the reference data. Normalise the data by
the heater power. Under normal circumstances (if the heater is stable) this processscales with Uheater2.
4. Compare patterns of heat flux and temperature rise and fall. In both cases relative tothe values just before heating.
• When the signal patterns match, amplitude differences, after correction for heater
power, point towards sensor instability. In this case recalibration of the sensor
may be required (Figure 2.5.1).
• Non-matching patterns point towards changes in sensor environment. This can for
example be the result of a loss of thermal contact between sensor and object(Figure 2.5.2) or the presence of convective heat losses (Figure 2.5.3).

H TR 0 2 s e ri e s man u a l v 220 4

13/26

Figure 2.5.1 In-situ sensor stability check. Comparison of responses to stepwise heating
relative to reference curves. Normalised to heater power (P) and relative to the heat flux
and the temperature just before heating. Solid graphs show heat flux, dotted graphs showtemperature. The black HF and T signals are the reference curves at installation. The
sensor shows non-stability, loses sensitivity over time, which results in the red responses:
equal response times, lower heat flux and equal temperature rise.

Figure 2.5.2 In-situ sensor stability check. Comparison of responses to stepwise heating
relative to reference curves. Normalised to heater power (P) and relative to the heat flux
and the temperature just before heating. Solid graphs show heat flux, dotted graphs showtemperature. The black HF and T signals are the reference curves at good thermal contact.
The sensor loses thermal contact, which results in the blue responses: slower response
times, lower heat flux and higher temperature rise.

H TR 0 2 s e ri e s man u a l v 220 4

14/26

Figure 2.5.3 In-situ sensor stability check. Comparison of responses to stepwise heating
relative to reference curves. Normalised to heater power (P) and relative to the heat flux
and the temperature just before heating. Solid graphs show heat flux, dotted graphs
show temperature. The black HF and T signals are the reference curves at zero windspeed. The sensor is exposed to convection, which results in the grey responses: faster
response times at lower heat flux and lower temperature rise.

H TR 0 2 s e ri e s man u a l v 220 4

15/26

3

Specifications of HTR02 series

3.1

Specifications of HTR02 series

HTR02 series is a heater with 4-wire connection with a known surface area and electricalresistance. It is designed for calibration and functionality checks of FHF-type sensors but
can also be used for general heating purposes.
Table 3.1 Specifications of HTR02 series (continued next page).
HTR02 SERIES SPECIFICATIONS
Product typeMeasurement function / required
programming
Required readout

Rated load on the cable
Rated bending radius
Operating temperature range
Heater length and width per dimension
HTR02-50X50
HTR02-85X85
Heater area
HTR02-50X50
HTR02-85X85
Passive guard area
HTR02-50X50
HTR02-85X85
Guard width to thickness ratio
HTR02-50X50
HTR02-85X85
Heater thickness
Heater thermal resistanceHeater thermal conductivity
Standard cable length
Heater wiring
Wire diameter
Marking
IP protection class
Rated operating relative humidity range
Gross weight including 2 m wires
Net weight including 2 m wires
ELECTRICAL CHARACTERISTICS

foil heater
depends on the application
1 x current channel and 1 x voltage channel,
alternatively 1 x current channel or alternatively 1
voltage channel.
currents may be measured using a voltage channel
which acts as a current measurement channel using acurrent sensing resistor
heater: 1 x switchable 12 VDC≤ 1.6 kg
≥ 7.5 x 10-3 m-40 to +150 °C(48 x 47.6) x 10-3 m(83 x 82.6) x 10-3 m
2381 x 10-6 m2
7022 x 10-6 m2
2152 x 10-4 m2
3692 x 10-4 m2
6 m/m
6 m/m
0.1 x 10-3 m
4 x 10-4 K/(W/m2)
0.27 W/(m·K)
2m
4 x copper wire, AWG 28, solid core, bundled with PFA
sheath1 x 10-3 m
1 x label at the end of HTR02’s cable, showing serial
number and nominal resistanceIP67
0 to 100 %approx. 0.5 kg
approx. 0.5 kg

Heater resistance (nominal) per dimension (measured value supplied with each sensor in the
production report)
HTR02-50X50 120 Ω ± 10 %HTR02-85X85 40 Ω ± 10 %Temperature coefficient of resistance< 0.02 %/°C
Heater rated power supply
24 VDCH TR 0 2 s e ri e s man u a l v 220 4

16/26

Heater power supply
12 VDC (nominal)
Power consumption at 12 VDC per dimension
HTR02-50X50 1.20 W
HTR02-85X85 3.60 W
Nominal heat flux at 12 VDC per dimension
HTR02-50X50 500 W/m²
HTR02-85X85 500 W/m²
INSTALLATION AND USE
Recommended number of heaters
Installation
Wire extension

H TR 0 2 s e ri e s man u a l v 220 4

one per sensor per measurement location
see recommendations in this user manual
see chapter on cable extension or order heaters withlonger cables

17/26

3.2

Dimensions of HTR02 series

Figure 3.2.1 Models HTR02 -50X50 and -85X85; Y1 = 47.6 or 82.6 and Y2=48 or 83,
dimensions in x 10-3 m(1)
heater area(2)
passive guard(3)
connection block for strain relief(4)cable, standard length C = 2 m

H TR 0 2 s e ri e s man u a l v 220 4

18/26

4

Installation of HTR02 series

4.1 Site selection and installation
Table 4.1.1 Recommendations for installation of HTR02 series.
Surface cleaning andlevellingcreate a clean and smooth surface of at least the same outer dimensionsof the heater: (50 x 50) or (85 x 85) x 10-3 m

Mounting: avoiding
strain on the heaterto-cable transition

the heater-to-cable transition is vulnerable
during installation as well as operation, the user should provide proper
strain relief of the cable so that the transition is not exposed to significant
force
first install the cable including strain relief and after that install the heater

Mounting: using a
guard

In case the sensor is smaller than the HTR02 heater, a guard isrecommended. We suggest making a guard of a material with equal
thermal resistance and thickness for best measurement results. See
section 2.3.

Mounting:
curved surfaces

when mounting HTR02 on curved surfaces, observe the rated bending
radiusMounting:
combination with heat
flux sensor

when mounting the HTR02 in combination with a heat flux sensor such as
the FHF05, keep the directional sensitivity of the heat flux sensor and theposition of the heater in mind

Short term
installation

avoid any air gaps between heater and surface. Air thermal conductivity
is in the 0.02 W/(m·K) range, while a common glue has a thermal
conductivity around 0.2 W/(m·K). A 0.1 x 10-3 m air gap increases theeffective thermal resistance of the sensor by 200 %to avoid air gaps, we recommend thermal paste or glycerol for short term
installation
use tape to fixate the connection block of the heaterusually, the cables are provided with an additional strain relief, forexample using a cable tie mount as in Figure 4.1.1

Permanent
installation

for long-term installation, fill up the space between heater and object
with silicone construction sealant, silicone glue or silicone adhesive, thatcan be bought in construction depots.
we discourage the use of thermal paste for permanent installation
because it tends to dry out. Silicone glue is more stable and reliable

H TR 0 2 s e ri e s man u a l v 220 4

19/26

Figure 4.1.1 Installation of model HTR02-50X50 using tape to fixate the sensor and theconnection block. Extra strain relief of the cable is provided using cable tie mounts
equipped with double-sided tape as adhesive. As indicated in Table 4.1.1, tapes fixating
the sensor are preferably taped over the passive guard area. In this case, a third tape (inthe middle) is added for extra support.

H TR 0 2 s e ri e s man u a l v 220 4

20/26

4.2 Electrical connection
To apply a heat flux, HTR02 should be connected to a power supply. If a variable heat
flux is required, the heater can either be connected via a solid-state relay controlled by apulse-width modulated (PWM) signal or to a programable power supply (see figure
4.2.1). The HTR02 electrical connections are explained in table 4.2.1 When connecting
HTR02, always observe the rated heater voltage. Users must make sure that the used
power supply is able to source sufficient current.
Table 4.2.1 The electrical connections of HTR02. The heater has a cable consisting offour wires. The two yellow wires are equivalent, and the two grey wires are equivalent.
Together they serve to make a 4-wire connection to the heater.
WIRE

HEATER

Yellowheater power [+]Yellowheater measure [+]Greyheater power [−]Greyheater measure [−]NOTICE
Putting more than 24 Volt across the sensor wiring
can lead to permanent damage to the heater.
The heat generated by HTR02 can be accurately determined by measuring the heater
voltage and current in a four-point measurement. To this end HTR02 has a four-wireconnection: two yellow wires and two grey wires. A voltmeter should be used to measure
the voltage between one the yellow and one of the grey leads and an ammeter should be
used to measure the current through the other yellow and grey leads that are used toapply a voltage to HTR02. See figure 4.2.1
Alternatively, either a measured voltage or a measured current can be combined with aknown heater resistance to compute the heat generated by HTR02. Please refer tosection 2.1 for more details on how to compute the heater power and applied heat flux.
Suggested HTR02 wiring is shown in figure 4.2.1. The heater serial number andresistance are shown on the HTR02 product certificate and on the label at the end of thecable.
When extending HTR02 cable please consider the thickness and electrical resistance of
the wires: too thin wires may lead to excessive heating of the wires themselves.

H TR 0 2 s e ri e s man u a l v 220 4

21/26

Figure 4.2.1 Suggested HTR02 heater wiring. Two heater wires are used to carry theheater current; the two others are used to measure the voltage over the heater. There isno significant current flowing though voltage measurement wires so that there is no
voltage drop over these wires. This “4-wire connection” measures the true voltage overthe heater.

H TR 0 2 s e ri e s man u a l v 220 4

22/26

5

Maintenance and trouble shooting

5.1 Recommended maintenance and quality assurance
HTR02 series perform reliably at a low level of maintenance. Unreliable heater output canbe detected by scientific judgement, for example by looking for unreasonably large orsmall measured values. The preferred way to ensure a reliable heater output, is a regularcritical review of the measured data.
Table 5.1.1 Recommended maintenance of HTR02 series. If possible, the data analysis
is done daily.
MINIMUM RECOMMENDED HEAT FLUX SENSOR MAINTENANCE
INTERVALSUBJECTACTION1

1 weekdata analysis

compare measured data to the maximum possible or
maximum expected heater power, to other measurementsfrom other redundant instruments and to data previously
measured under identical circumstances.
Look for any patterns and events that deviate from what isnormal or expected. Compare to acceptance intervals.

2

6 months

inspection

inspect cable and wire quality, inspect mounting, inspect
location of installation
look for seasonal patterns in measurement data

3

2 years

lifetime
assessment

judge if the instrument will be reliable for another 2 years, or
if it should be replaced

H TR 0 2 s e ri e s man u a l v 220 4

23/26

5.2 Trouble shooting
Table 5.2.1 Trouble shooting for HTR02 series.
GeneralInspect the heater for any damage. Inspect the quality of mounting / installation.
Inspect if the wires are properly attached to the data logger.
Check the condition of the cable.
Check the datalogger program in particular if the correct resistance is enteredwhen not measuring according to the 4-wire method. HTR02 resistance and serial
number are shown on the product certificate and on the sticker at the end of thecable.
Check the electrical resistance of the heater between the wires of the heater. You
may use a 4-wire connection. Use a multimeter at the 1k Ω range. Typicalresistance should be around 120 Ω for model 50X50 and around 40 Ω for model
85X85 ± 10 %. Infinite resistance indicates a broken circuit; zero or a lower than1 Ω resistance indicates a short circuit.
Check the heater resistance value in Ω on the product certificate.

The heater
Check the presence of strong sources of electromagnetic radiation (radar, radio).
measurements Check the condition of the heater cable.
show
Check if the cable is not moving during the measurement.
unexpectedvariations

5.3 Calibration and checks in the field
The recommended calibration interval of heat flux sensors is 2 years.
Recalibration of field heat flux sensors is ideally done by the sensor manufacturer. You
may also calibrate by yourself following chapter 2.4.
On-site field calibration is possible by comparison to a calibration reference sensor.
Usually mounted side by side, alternatively mounted on top of the field sensor.
Hukseflux main recommendations for field calibrations are:1) Compared to a calibration reference of the same brand and type as the field sensor
2) connect both to the same electronics, so that electronics errors (also offsets) areeliminated3) mount all sensors on the same platform, so that they have the same bodytemperature4) typical duration of test: > 24 h5) typical heat flux used for comparison: 500 W/m²
6) correct for deviations of more than ± 20 %. Lower deviations should be interpreted as
acceptable and should not lead to a revised sensitivity

H TR 0 2 s e ri e s man u a l v 220 4

24/26

6

Appendices

6.1 EU declaration of conformity

We,

Hukseflux Thermal Sensors B.V., Delftechpark 31, Delft,
The Netherlands

hereby declare under our sole responsibility that:
Product model
Product type

HTR02 series, all models
heater for calibration and verification of performance of
FHF-type heat flux sensors

is in conformity with the following directives:
2011/65/EU, EU 2015/863

The Restriction of Hazardous Substances Directive

This conformity is declared using the relevant sections and requirements of the following
standards:
Hazardous substances

RoHS 2 and EU 215/863 amendment known as RoHS 3

Eric HOEKSEMA
Director
Delft, 15 November 2022

H TR 0 2 s e ri e s man u a l v 220 4

25/26

H TR 0 2 s e ri e s man u a l v 220 4

26/26