Hukseflux FHF04SC User manual

Copyright by Hukseflux | manual v2101| www.hukseflux.com | [e-mail]
USER MANUAL FHF04SC
Self-calibrating foil heat flux sensor with thermal
spreaders and heater
Hukseflux
Thermal Sensors

FHF04SC manual v2101 2/41
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 9
1.1 Ordering FHF04SC 9
1.2 Included items 9
1.3 Quick instrument check 10
2Instrument principle and theory 11
2.1 Theory of operation 11
2.2 The self-test 14
2.3 Calibration 14
2.4 Application example 15
2.5 Application example: non-invasive core temperature measurement 17
3Specifications of FHF04SC 18
3.1 Specifications of FHF04SC 18
3.2 Dimensions of FHF04SC 21
4Standards and recommended practices for use 22
4.1 Heat flux measurement in industry 22
5Installation of FHF04SC 23
5.1 Site selection and installation 23
5.2 Installation on curved surfaces 25
5.3 Electrical connection 26
5.4 Requirements for data acquisition / amplification 29
6Maintenance and trouble shooting 30
6.1 Recommended maintenance and quality assurance 30
6.2 Trouble shooting 31
6.3 Calibration and checks in the field 32
7Appendices 34
7.1 Appendix on wire extension 34
7.2 Appendix on using FHF04SC with BLK – GLD sticker series 35
7.3 Appendix on standards for calibration 36
7.4 Appendix on calibration hierarchy 36
7.5 Appendix on correction for temperature dependence 37
7.6 Appendix on measurement range for different temperatures 38
7.7 Appendix on temperature measurement accuracy 39
7.8 EU declaration of conformity 40

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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)
Area A m²
Electrical resistance R Ω
Electrical power P W
subscripts
property of heatsink heatsink
property of heater heater
property of sensor sensor
maximum value, specification limit maximum

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Introduction
FHF04SC is a combination of the standard model FHF04 heat flux sensor and a heater.
The heater allows the user to perform self-tests, verifying sensor functionality and
stability during use, without having to remove the sensor. FHF04SC 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.
FHF04SC measures heat flux through the object in which it is incorporated or on which it
is mounted, in W/m2. The sensor in FHF04SC is a thermopile. This thermopile measures
the temperature difference across FHF04SC’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 FHF04SC 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.
Figure 0.1 FHF04SC self-calibrating foil heat flux sensor with thermal spreaders and
heater, showing its front and back side

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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 wire
connection, data acquisition, thermal connection of the sensor to its environment and
data processing are tested. Heat flux sensors are often kept installed for as long as
possible. 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.
The FHF04SC self-calibrating foil heat flux sensor has 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 metal connection block, may be used as strain relief
•IP protection class: IP67 (essential for outdoor application)
•integrated thermal spreaders for low thermal conductivity dependence
FHF04SC’s 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
\
Figure 0.2 Application example: FHF04SC being installed to measure heat flux on a pipe

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Using FHF04SC is easy. It can be connected directly to commonly used data logging
systems. The heat flux in W/m2is calculated by dividing the FHF04SC output, a small
voltage, by the sensitivity. The sensitivity is provided with FHF04SC on its product
certificate.
Equipped with wires with strain relief, protective covers on both sides and potted so that
moisture does not penetrate the metal connection block, FHF04SC has proven to be very
robust and stable. The connection block may be used as strain relief between sensors
and wires.
FHF04SC calibration is traceable to international standards. The factory calibration
method follows the recommended practice of ASTM C1130 - 17. When used under
conditions that differ from the calibration reference conditions, the FHF04SC sensitivity to
heat flux may be different than stated on its certificate. See Chapter 2 in this manual for
suggested solutions.
Would you like to study energy transport / heat flux in detail? Hukseflux helps taking this
measurement to the next level: order FHF04SC 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. They can be applied to the sensor by the user or at the factory; see the BLK
– GLD sticker series user manual and installation video for instructions.
Figure 0.3 FHF04SC heat flux sensor: with BLK-5050 and GLD-5050 stickers
absorbs radiation
reflects radiation

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See also:
•model FHF04, our standard model for general-purpose heat flux measurement
•model FHF03, our most economical foil heat flux sensor
•model HFP01 for increased sensitivity (also consider putting two or more FHF04s in
series)
•BLK - GLD sticker series 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 FHF04SC
The standard configuration of FHF04SC is with 2 metres of wire.
Common options are:
•with 5 metres wire length
•with LI19 hand-held read-out unit / datalogger; NOTE: LI19 does not measure
temperature, only heat flux
•BLK-5050 black sticker (to measure radiative as well as convective heat flux)
•GLD-5050 gold sticker (to measure convective heat flux only)
•BLK - GLD sticker series can also be ordered pre-applied at the factory
1.2 Included items
Arriving at the customer, the delivery should include:
•heat flux sensor FHF04SC with wires of the length as ordered
•product certificate matching the instrument serial number
Figure 1.2.1 FHF04SC’s serial number and sensitivity are visible on the metal connection
block. FHF04SC is delivered with bundled wiring.

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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 sticker on the metal connection
block 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 0.1 Ω/m. Typical resistance should be the nominal sensor resistance of 200 Ω
plus 0.2 Ω for the total resistance of two wires (back and forth) for each m. 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 0.1 Ω/m, for the constantan wiring this is 2.5 Ω/m.
Typical resistance should be the nominal thermocouple resistance of 2.5 Ω plus 2.6 Ωfor
the total resistance of the two wires (back and forth) of each m. Infinite resistance
indicates a broken circuit; zero or a lower than 1 Ω resistance indicates a short circuit.
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 wit the heater) 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.
6. Check the electrical resistance of the heater between any of the yellow wires and any
of the grey wires. Use a multimeter at the 1 kΩ range. Typical resistance should be
around 100 Ω. Infinite resistance indicates a broken circuit; zero or a lower than 1 Ω
resistance indicates a short circuit.
7. Check the electrical resistance between the 2 yellow wires and the 2 brown 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.

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2Instrument principle and theory
FHF04SC’s scientific name is heat flux sensor. A heat flux sensor measures the heat flux
density through the sensor itself. This quantity, expressed in W/m2, is usually called
“heat flux”.
FHF04SC users typically assume that the measured heat flux is representative of the
undisturbed heat flux at the location of the sensor. Users may also apply corrections
based on scientific judgement. FHF04SC has an integrated film heater. At a regular
interval the film heater can be activated to perform a self-test. The self-test results in a
verification of sensor performance. See the next chapters for examples how the self-test
may be used. Implicitly also wire connection, data acquisition and data processing are
tested.
2.1 Theory of operation
The sensor in FHF04SC is a thermopile. This thermopile measures the temperature
difference across the polyimide body of FHF04SC. Working completely passive, the
thermopile generates a small voltage that is a linear function of this temperature
difference. The heat flux is proportional to the same temperature difference divided by
the effective thermal conductivity of the heat flux sensor body.
Figure 2.1.1 The general working principle of a heat flux sensor. The sensor inside
FHF04SC is a thermopile. A thermopile consists of a number of thermocouples, each
consisting of two metal alloys (marked 1 and 2), electrically connected in series. A single
thermocouple generates an output voltage that is proportional to the temperature
difference between its hot- and cold joints. Putting thermocouples in series amplifies the
signal. In a heat flux sensor, the hot- and cold joints are located at the opposite sensor
surfaces (4 and 5). In steady state, the heat flux (6) is a linear function of the
temperature difference across the sensor and the average thermal conductivity of the
sensor body (3). The thermopile generates a voltage output proportional to the heat flux
through the sensor. The exact sensitivity of the sensor is determined at the manufacturer
by calibration, and can be found on the product certificate that is supplied with each
sensor.
5
4
321
6

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Using FHF04SC is easy. For readout the user only needs an accurate voltmeter that
works in the millivolt range. To convert the measured voltage, U, to a heat flux Φ, the
voltage must be divided by the sensitivity S, a constant that is supplied with each
individual sensor.
Φ = U/S (Formula 2.1.1)
FHF04SC is designed such that heat flux from the back side to the front side generates a
positive voltage output signal. The dot on the foil indicates the front side.
Unique features of FHF04SC include flexibility (bending radius ≥ 15 x 10-3 m), high
sensitivity, low thermal resistance, a wide temperature range, a fast response time, IP67
protection class rating (essential for outdoor application), and the inclusion of thermal
spreaders to reduce thermal conductivity dependence.
FHF04SC is calibrated under the following reference conditions:
•conductive heat flux (as opposed to radiative or convective heat flux)
•homogeneous heat flux across the sensor and guard surface
•room temperature
•heat flux in the order of 600 W/m2
•mounted on aluminium heat sink
FHF04SC has been calibrated using a well-conducting metal heat sink, representing a
typical industrial application, at 20 °C and exposing it to a conductive heat flux. When
used under conditions that differ from the calibration reference conditions, for example at
extremely high or low temperatures, or exposed to radiative flux, the FHF04SC
sensitivity to heat flux may be different than stated on the certificate. In such cases, the user
may choose:
•not to use the sensitivity and only perform relative measurements / monitor changes
•reproduce the calibration conditions by mounting the sensor on or between metal foils
•design a dedicated calibration experiment, for example using a foil heater which
generates a known heat flux
•apply our BLK-5050 sticker to the sensor surface to absorb radiation
•apply our GLD-505 sticker to the sensor surface to reflect radiation
The user should analyse his own experiment and make his own uncertainty evaluation.
The FHF04SC rated operating temperature range for continuous use is -70 to +120 °C,
for short intervals a peak temperature of +150 °C is allowed. Prolonged exposure to
temperatures near +150 °C can accelerate the aging process.

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Figure 2.1.2 Heat flux from the back side to the front side generates a positive voltage
output signal. The dot on the foil indicates the front side.

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2.2 The self-test
A self-test is started by switching on FHF04SC’s heater, while recording the sensor
output signal and the heater power, and is finalised by switching the heater off. During
the heating interval a current is fed through the film heater, which generates a known
heat flux. To calculate this heat flux the heater power Pheater must be measured
accurately. This power 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)
The user must interrupt the normal measurement of the heat flux during the self-test.
We recommend that the heat flux value of just before the heating interval is copied for at
least 360 s.
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 Section 2.4 and 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 Section 2.3 for more details.
2.3 Calibration
FHF04SC calibration is traceable to international standards. The factory calibration
method follows the recommended practice of ASTM C1130 - 17. When used under
conditions that differ from the calibration reference conditions, the FHF04SC sensitivity to
heat flux may be different than stated on its certificate.
In a typical calibration setup as shown in the next figure, the FHF04SC is positioned
between an insulating material and a heatsink with the FHF04SC heater on the side of
the insulating material. In such a setup, the heat losses through the insulation may be
ignored. In this case all heat generated by the heater flows through the heat flux sensor
to the heat 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 Sis the voltage output Usensor divided by the applied heat
flux Φ:
S = Usensor/Φ(Formula 2.3.2)

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The reproducibility of this test is much improved when using contact material (such as
glycerol or a thermal paste) between sensor and heat sink.
Figure 2.3.1 Calibration of FHF04SC; a typical stack used for calibration consists of a
block of metal (mass > 1 kg), for example aluminium (5), the heat flux sensor (3), with
heater (2) and an insulation foam (1). Under these conditions, heat losses through the
insulation are negligible. Heat flux (4) flows from hot to cold.
2.4 Application example
The FHF04SC heater can be used to check for stable performance of the FHF04SC at
regular intervals without the need to uninstall the sensor from its application.
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 the heater. Upon installing the
sensor a reference measurement should be made. A time trace of the heater power, the
measured heat flux and the measured sensor temperature should be stored as reference
data. Stable operation of the sensor can then be confirmed at any time by comparing to
the reference measurement. The test protocol consists of the 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 process
scales with Uheater2.
1
4
2
3
5

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4. Compare patterns of heat flux and temperature rise and fall. In both cases relative to
the values just before heating.
•When signal patterns match but the amplitude differs (after correction for heater
power), this points towards sensor instability. In such a case, recalibration of the
sensor may be required.
•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 2.4.1 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 show
temperature. The black HF and T signals are the reference curves at good thermal contact.
When the sensor loses thermal contact, this results in the red responses: slower response
times, lower heat flux and higher temperature rise.
Figure 2.4.2 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
show temperature. The black HF and T signals are the reference curves at zero wind
speed. The sensor is exposed to convection, which results in the blue responses: faster
response times at lower heat flux and lower temperature rise.

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2.5 Application example: non-invasive core temperature
measurement
FHF04SC may be used for non-invasively measuring the core temperature of objects, for
example of human beings.
The measurement is usually done with a sandwich of objects – heat flux & temperature
sensor-heater- insulation material. To determine the core temperature, the heater power
should be adjusted such that the heat flux equals zero. When zero heat flux is attained,
the temperature gradient equals zero and the measured temperature equals the core
temperature.
To perform such a measurement a PID controller can be used to regulate the heating
power. The setpoint of the PID controller should be set to zero heat flux. The PID
controller can regulate the heater power either through a 0 – 12 V programmable power
supply or via a solid-state relay controlled with a pulse-width-modulated signal.
Figure 2.5.1 FHF04SC in a non-invasive core-temperature measurement. For
measurement of the core temperature (1), the heater (5) is controlled to a setpoint of zero
heat flux (2) measured by the heat flux sensor (3). At zero heat flux, the temperature of
the core (1) and the temperature sensor (6) are equal. Insulation material (4) is attached
to work at stable boundary conditions.
1
4
23
56

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3Specifications of FHF04SC
3.1 Specifications of FHF04SC
FHF04SC measures the heat flux density through the surface of the sensor. This
quantity, expressed in W/m2, is called heat flux. Working completely passive, using a
thermopile sensor, FHF04SC generates a small output voltage proportional to this flux. It
can only be used in combination with a suitable measurement system.
Table 3.1.1 Specifications of FHF04SC (continued on next pages)
FHF04SC SPECIFICATIONS
Sensor type
foil heat flux sensor
Sensor type according to ASTM
heat flow sensor or heat flux transducer
Measurand
heat flux
Measurand in SI units
heat flux density in W/m2
Measurement range
(-10 to +10) x 103W/m2 at heat sink temperature 20 °C
see appendix for detailed calculations
Sensitivity range
9 - 13 x 10-6 V/(W/m2)
Sensitivity (nominal)
11 x 10-6 V/(W/m2)
Directional sensitivity
heat flux from the back side to the front side (side with
the dot) generates a positive voltage output signal
Increased sensitivity
multiple sensors may be put electrically in series. The
resulting sensitivity is the sum of the sensitivities of
the individual sensors
Expected voltage output
(-100 to +100) x 10-3 V
turning the sensor over from one side to the other will
lead to a reversal of the sensor voltage output
Measurement function / required
programming
without self-test: Φ= U/S
with self-test: depends on application
Required readout
1 differential voltage channel or 1 single ended
voltage channel, input resistance > 10
6
Ω
Optional readout
1 temperature channel
Rated load on wires
≤1.6 kg
Rated bending radius
≥15 x 10-3 m
Rated operating temperature range,
continuous use
-70 to +120 °C
Rated operating temperature range,
short interval
-160 to +150 °C
(contact Hukseflux when measuring at -160 °C)
Temperature dependence
< 0.2 %/°C
Non-linearity
< 5 % (0 to 10 x 10³ W/m²)
Solar absorption coefficient
0.75 (indication only)
Thermal conductivity dependence
Negligible, < 3 %/(W/m·k) from 270 to 0.3 W/m·K
Sensor length and width
(50 x 50) x 10-3 m
Sensing area
9 x 10-4 m2
Sensing area length and width
(30 x 30) x 10-3 m
Passive guard area
16 x 10-4 m2
Guard width to thickness ratio
33
Sensor thickness
0.7 x 10-3 m
Sensor thermal resistance
24 x 10-4 K/(W/m2)
Sensor thermal conductivity
0.29 W/(m·K)
Response time (95 %)
6 s
Sensor resistance range
160 to 240 Ω
Required sensor power
zero (passive sensor)

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Table 3.1.1 Specifications of FHF04SC (started on previous page)
Temperature sensor
type T thermocouple
Temperature sensor accuracy
± 2 % (of temperature in ˚C), see appendix for more
information
Standard wire length
2 m
Wiring
3 x copper and 1 x constantan wire, AWG 24, stranded
Wire diameter
1 x 10-3 m
Marking
dot on foil indicating front side of the heat flux sensor;
1 x label on metal connection block, showing serial
number and sensitivity
IP protection class
IP67
Rated operating relative humidity range
0 to 100 %
Use under water
FHF04SC is not suitable for continuous use under
water
Gross weight including 2 m wires
approx. 0.5 kg
Net weight including 2 m wires
approx. 0.5 kg
HEATER
Heater resistance (nominal)
100 Ω ± 10%
(measured value supplied with each sensor in the
production report)
Heater rated power supply
24 VDC
Heater power supply
12 VDC (nominal)
Heater area
0.002062 m²
Suggested current sensing resistor
10 Ω ± 0.1 %, 0.25 W, < 15 ppm/°C
SELF-TEST
Power consumption during heating
interval (nominal)
1.44 W (@ 12 VDC)
Self-test duration
360 s (nominal)
Heater interval duration
180 s (nominal)
Settling interval duration
180 s (nominal)
INSTALLATION AND USE
Typical conditions of use
in experiments, in measurements in laboratory and
industrial environments. Exposed to heat fluxes for
periods of several minutes to several years.
Connected to user-supplied data acquisition
equipment. Regular inspection of the sensor.
Continuous monitoring of sensor temperature. No
special requirements for immunity, emission, chemical
resistance.
Recommended number of sensors
2 per measurement location
Installation
see recommendations in this user manual
Bending
see chapter on installation on curved surfaces
Wire extension
see chapter on wire extension or order sensors with
longer wires
CALIBRATION
Calibration traceability
to SI units
Product certificate
included
(showing calibration result and traceability)
Calibration method
method HFPC, according to ASTM C1130 - 17
Calibration hierarchy
from SI through international standards and through
an internal mathematical procedure
Calibration uncertainty
< ± 5 % (k = 2)
Recommended recalibration interval
2 years
.

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Table 3.1.1 Specifications of FHF04SC (started on previous pages)
Calibration reference conditions
20 °C, heat flux of 600 W/m2, mounted on aluminium
heat sink, thermal conductivity of the surrounding
environment 0.0 W/(m·K)
Validity of calibration
based on experience the instrument sensitivity will not
change during storage. During use the instrument
“non-stability” specification is applicable. When used
under conditions that differ from the calibration
reference conditions, the FHF04SC sensitivity to heat
flux may be different than stated on its certificate. See
the chapter on instrument principle and theory for
suggested solutions
Field calibration
is possible by comparison to a calibration reference
sensor. Usually mounted side by side, alternative on
top of the field sensor. Preferably reference and field
sensor of the same model and brand. Typical duration
of test > 24 h
MEASUREMENT ACCURACY
Uncertainty of the measurement
statements about the overall measurement
uncertainty can only be made on an individual basis.
VERSIONS / OPTIONS
With longer wire length
option code = wire length in metres
With black sticker applied
BLK-5050 applied to the sensor at the factory to
absorb radiation
With gold sticker applied
GLD-5050 applied to the sensor at the factory to
reflect radiation
ACCESSORIES
Hand-held read-out unit
LI19 handheld read-out unit / datalogger
NOTE: LI19 does not measure temperature, only heat flux
Separate black stickers
BLK-5050 to absorb radiation, to be applied by the user
Separate gold sticker
GLD-5050 to reflect radiation, to be applied by the user