Hukseflux

Thermal Sensors

USER MANUAL HF03-LI19
Portable heat flux sensor
with read-out unit / datalogger

Copyright by Hukseflux | manual v2020 | www.hukseflux.com | info@hukseflux.com

Warning statements
HF03-LI19 does not carry an EC type examination
certificate (ATEX).
HF03 is suitable for use during an exposure intervalof 10 min and heat flux up to 10 x 103 W/m2. LI19 issuitable for exposure up to 2 x 103 W/m2.
Software supplied with the instrument might not be
the latest version. Download the latest version fromwww.hukseflux.com/page/downloads.
Switch off HF03-LI19 after use, take spare batteries
with you.
Hukseflux performs traceable calibrations and iscertified according to ISO 9001, but is not an ISO
17025 accredited calibration laboratory.

HF03-LI19 manual v2020

2/25

Contents
Warning statements
Contents
List of symbols
Introduction
1
Ordering and checking at delivery
1.1
Ordering HF03-LI19
1.2
Included items
1.3
Latest software
1.4
Quick instrument functionality check2
Instrument principle and theory
3
Specifications of HF03-LI19
4
Installation of HF03-LI19
4.1
Electrical connection
4.2
Software installation on the PC
5
Recommended practices for use
5.1
Short user guide
5.2
Directions for measurement
5.3
Battery replacement
5.4
The LI19 user interface on PC
6
Maintenance and trouble shooting
6.1
Recommended maintenance and quality assurance
6.2
Trouble shooting
6.3
Recoating / repainting of sensor surfaces
7
Appendices
7.1
Appendix on calibration hierarchy
7.2
Typical heat flux ranges
7.3
Typical HF03 sensitivity
7.4
EU declaration of conformity

HF03-LI19 manual v2020

2
3
4
5
8
8
8
8
9
10
11
14
14
14
15
15
16
16
17
19
19
20
20
22
22
22
22
23

3/25

List of symbols
Quantities

SymbolUnit

Heat flux
Voltage output
Sensitivity
Temperature
Resistance

Φ
U
S
T
R

W/m²
V
V/(W/m2)°CΩ

Subscripts
N/A

HF03-LI19 manual v2020

4/25

Introduction
HF03 is a heat flux sensor commonly used in fire testing. It is designed for short(exposure time < 10 min) monitoring and measurement in high flux environments in theheat flux range up to 10 x 103 W/m2.
LI19 displays the measured heat flux. Once programmed with the sensitivity of theconnected sensor, the display will show the actual value of the heat flux in W/m2.
Programming LI19 is done through its PC user interface. LI19 communicates over USB.
We recommend downloading the latest software. LI19 may also be used to store
measured data. LI19 is battery powered, using 2 x AA-type batteries. Fresh batteries
allow 50 days of operation. HF03-LI19 is not rated for EEx (potentially explosive)
environments, nevertheless it is admitted in many cases, because the instrument
operates on 3 VDC only.
Operation of HF03-LI19 is easy. As LI19 has already been programmed at the factory,measurements can start by switching on the LI19. The data storage interval is set byusing the LI19 user interface software.
Hukseflux provides a traceable calibration. The reference standard at Hukseflux is ofsecondary standard level. It has been calibrated by comparison to the primary standardof the RISE Research Institutes of Sweden AB (formerly known as Statens
Provningsanstalt (SP)). HF03 sensors as supplied by Hukseflux are calibrated according
to ISO TS 14934-3. Hukseflux is ISO 9001 certified, but not an accredited measurementlaboratory according to ISO 17025.

Figure 0.1 HF03, pictured without and with the included protection cap. Standard cable
length is 5 m.

HF03-LI19 manual v2020

5/25

Figure 0.2 HF03-LI19 portable heat flux sensor with read-out unit

Figure 0.3 HF03-LI19 portable heat flux sensor with read-out unit in use for studying
flares.

HF03-LI19 manual v2020

6/25

1

2

8

50.0

3

kW/m2

4

LI-19

6

5

9

10

11

Figure 0.4 LI19 connected to HF03:(1) on/off switch, (2) 2 x chassis plugs with screwed signal wire clamp, (3) display, (4)unit marker, (5) USB connector, (6) battery compartment, (7) HF03 cable, (8) cablegland, (9) plastic hand-grip, (10) metal heat sink, (11) thermopile sensor with black
coating

HF03-LI19 manual v2020

7/25

1

Ordering and checking at delivery

1.1

Ordering HF03-LI19

HF03-LI19 is available in one standard version only.

1.2

Included items

Arriving at the customer, the delivery should include:
•
•
•
•
•
•
•
•
•

HF03 with protection cap
programmed LI19 with 2 x AA battery
2 spare batteries (type AA)transport case with space for sensors
LI19 product certificate
HF03 product certificate
strip with measurement unit markers
USB cable
LI19 software

1.3

Latest software

The latest software should be downloaded from: www.hukseflux.com/page/downloads

Figure 1.3.1 Screenshot of a plot created by the LI19 software user interface on PC

HF03-LI19 manual v2020

8/25

1.4

Quick instrument functionality check•connect the LI19 to the HF03 sensor,[white] wire to [red] plug, [green] wire to [black] plugswitch on the LI19
check sensor sensitivity settings on the display (displayed 1 s after start-up)
against the HF03 product certificate and on the handgrip
check the zero signal with the protection cap on the HF03
remove the protection cap from HF03
check the functionality of the system by short exposure to a strong heat flux
sourcestart measurement; write down measured values as seen on the screen

•
•
•
•
•
•

HF03-LI19 manual v2020

9/25

2

Instrument principle and theory

HF03 is a sensor that measures heat flux. It is mainly used to test reaction to fire andfire resistance. HF03 measures heat flux in the range of (0 to 10) x 103 W/m2. Equippedwith a black absorber, heat flux sensors of this type are designed for measurement in anenvironment in which heat flux is dominated by radiation. Using an open detector, HF03
is also sensitive to convective heat flux. This contribution is usually ignored. Applicationin environments with significant heat transport to the sensor by convection is possible
but requires a careful evaluation of the measurement uncertainty. HF03’s thermopile
sensor generates an output voltage proportional to the incoming irradiance.
The heat flux, Φ, in W/m2, is calculated by dividing the HF03 output, a small voltage U,
by the sensitivity S.
The measurement function of HF03 is:Φ = U/S(Formula 2.1)

The sensitivity is provided with HF03 on its product certificate.
For readout the user only needs an accurate voltmeter that works in the millivolt range,such as the LI19. 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.
LI19 performs the measurement of the sensor output voltage, as well as the conversion
to W/m2. For the conversion the HF03 sensitivity must be entered into the LI19. It also
stores data. The LI19 software serves as a user interface on PC.

HF03-LI19 manual v2020

10/25

3

Specifications of HF03-LI19

HF03-LI19 measures and displays the heat flux density through the surface of the HF03
sensor. This quantity, expressed in W/m2, is called heat flux. HF03 is rated for use inenvironments in which the heat flux is dominated by radiation at heat flux levels up to 10
x 103 W/m2. It measures the combined radiative and convective heat flux.
The rated exposure interval of HF03 is 10 min. LI19 should not be exposed to the sameheat flux source. LI19 is battery powered. Programming LI19 is done through its PC userinterface. It communicates via USB.
Table 3.1 Specifications of HF03-LI19 (continued on next pages)
HF03 SPECIFICATIONS
Sensor typeMeasurand
Measurand in SI units
Full field of view angle
Rated measurement range
Limiting measurement range
Output signal
Sensitivity range
Response tine (63 %)Measurement function / required
programming
Rated operating temperature range
Sensor resistance
Required sensor power
Rated operating relative humidity range
Standard cable length
Cable material type
Cable diameter
Wiring colour code
IP protection class
Sensor marking
Rated exposure time interval
Weight of metal sensor body
Metal heat capacity
Heat capacity of sensor body

HF03-LI19 manual v2020

portable heat flux sensor
heat flux
irradiance in W/m2
180 °0 to 10 x 103 W/m2
150 % of rated measurement range
DC voltage
0.1 to 0.7 x 10-6 V/(W/m2)< 450 x 10-3 s
Φ = U/S-30 to +80 °C (sensor body temperature)
25 Ω (nominal)
zero (passive sensor)
0 to 100 % (non condensing)5m
PUR
4 x 10-3 m
white [+], green [-]IP10
serial number and sensitivity are marked on hand grip
0 to 10 min
0.33 kg
400 J/(kg·K)
132 J/K

11/25

Table 3.1 Specifications of HF03-LI19 (started on previous pages, continued on the next page)HF03 INSTALLATION AND USE
Installation
HF03 CALIBRATION

HF03 is usually pointed at the main source of radiation

Calibration traceability
Standard governing calibration

to ITS-90
ISO TS 14934-3: Reaction-to-Fire Tests - calibrationof heat flux meters secondary calibration
included(showing calibration result and traceability)
SBGC secondary calibration method according to ISO
14934-3. The Hukseflux SBGC method follows therecommended practice of ISO 14934-3, however wecalibrate HF03 at one heat flux level only: 10 x 103
W/m2. Calibration relies on a comparison to asecondary standard heat flux sensor under a radiantheat source. The calibration reference has beencharacterised at 10 x 103 W/m2.
not accredited
ISO 9001

Product certificate
Calibration method

Calibration laboratory accreditation
Calibration laboratory management
system certification
Calibration hierarchy
Calibration uncertainty
Recommended recalibration interval
Calibration reference conditions
Validity of calibration
MEASUREMENT ACCURACY
Uncertainty of the measurement
ACCESSORIES
Spare part

HF03-LI19 manual v2020

from SI through international standards and throughan internal mathematical procedure< 6.5 % (k = 2)
1 yrcooling water temperature < 25 °C, heat flux at 10 x
103 W/m2 ± 20 %based on experience the instrument sensitivity will notchange during storage.
statements about the overall measurement
uncertainty can only be made on an individual basis.
see the chapter on uncertainty evaluation.

removable protection cap HF03

12/25

Table 3.1 Specifications of HF03-LI19 (started on previous pages)
LI19 SPECIFICATIONSInstrument typeMeasurand
Output in display with HF03
Stored measurement definition
Storage interval range
Display refreshment rate
Sample rate
Display resolution with HF03
Storage capacity
Rated operating temperature range
Temperature dependenceInternal power supply voltage
Battery type
Battery life
Rated exposure range
Latest software version
Connection to PC
User interface on PC
System requirements for use with PC
A/D conversion
Wiring colour code
Connection to sensor
Indicators on display

PACKAGING / TRANSPORT HF03-LI19
Gross weight
Net weight
Packaging

HF03-LI19 manual v2020

read-out unit / datalogger
analogue voltage with conversion to W/m2
heat flux in x 103 W/m2
minimum, maximum and average over storage
interval with conversion to W/m2
2 to 65535 s (selectable)
1 s-1
2 s-1
0.1 x 103 W/m2
3518 measurements-10 to +40 °C< 0.5 % + 3 x 10-6 V over rated range
3 VDC
2 x AA> 50 days (on fresh batteries)< 2 x 103 W/m2
see http://www.hukseflux.com/page/downloads
via USB 1.1 / 2.0 low speed
LI19 software
Windows XP and later, USB port
16 bits
red [+], black [-]2 x (female chassis plug for 4 mm banana plug, withscrewed signal wire clamp)
: data from PC to LI19
: data to PC from LI19
BAT: battery low
m: storing in memoryl:sampling active
approx. 2 kg
HF03-LI19 + transport casing (black plastic) andpackaging (carton box)
approx. 1 kg
HF03-LI19transport casing (black plastic) in carton box

13/25

4

Installation of HF03-LI19

4.1

Electrical connection

Table 4.1.1 The electrical connection of HF03 to LI19
HF03 OUTPUT

WIRE

LI19 PLUGS

signal [+]

White

Red

signal [ ‒ ]

Green

Black

groundBlack

not connected

Figure 4.1.1 Connectors and on/off switch on LI19. Connectors are 2 x female chassis
plugs for 4 mm banana plug, with screwed signal wire clamps

4.2

Software installation on the PC

The LI19 program is installed from the CD-ROM, or by downloading via internet.
Installation of the LI19 program is done automatically by the Windows installer. In caseolder program versions are in use, these must be uninstalled. For the latest version of
the LI19 software, see www.hukseflux.com/page/downloads.

HF03-LI19 manual v2020

14/25

5

Recommended practices for use

5.1

Short user guide

Table 5.1 Recommended practices for use
HF03-LI19 RECOMMENDED PRACTICES FOR USE
1

Unpack HF03-LI19

check shipment contents (see paragraph on included
items)

2

Double checkmake sure fresh batteries are installed and added asspares. Look at the BAT indicator on screen

3

Download the latest
software to the PC

see www.hukseflux.com/page/downloads

4

Put the unit marker into
place

for use with HF03 the unit marker kW/m2 must be used.

5

Connect HF03 to LI19

see the paragraph on electrical connections:
HF03 [white] to LI19 [red]. HF03 [green] to LI19 [black]6

Switch on the LI19

use the push button switch on top. Check the sensitivity
setting of LI19 against the HF03 sensitivity on the handgrip. This sensitivity appears 1 s after switching on the
LI19, and should be between 100 and 700

7

Look for indicators on thedisplay

: data from PC to LI19
: data to PC from LI19
BAT: battery low
m: storing in memoryl:measurement with data storage active

8

Optional: Connect LI19 to
the PC, make contact toLI19 via the user interface

see the paragraph on the LI19 software

9

Optional: Check the LI19
settings via PC

check the sensitivity setting and the definition of stored
measurements

10

Optional: Disconnect LI19
from the PC

11

Remove the HF03
protection cap

inspect the heat flux sensor surface. The 10 x 10-3 m
diameter sensing surface should be black

12

Perform measurements

do not expose HF03 for more than 10 min to strong
radiation sources. Do not expose LI119 to strong
radiation sources.
write down measured data

13

Optional: backup data toPC

14

Switch off LI19

15

Store HF03-LI19 in its
transport case in a dry
environment

HF03-LI19 manual v2020

15/25

5.2

Directions for measurement

HF03 and LI19 are suitable for outdoor use in a dry environment only. LI19’s rated
temperature range is from -10 to + 40 °C.
HF03 measures the heat flux through the plane of the black sensor. Make sure theorientation of the HF03 matches the orientation of the plane of interest.
For studies of exposure of personnel and equipment, the maximum or worst-case heat
flux is usually found by measuring at the relevant location and by pointing the HF03 at
the strongest local radiation source.

5.3

Battery replacement

Batteries must be replaced on a regular basis. To access the battery compartment, thebottom panel of LI19 can be removed manually. 2 x AA batteries are needed.

Figure 5.3.1 Battery replacement of LI19

HF03-LI19 manual v2020

16/25

5.4

The LI19 user interface on PC

When the LI19 program is activated, and the LI19 is switched on and connected, theprogram will automatically recognise the LI19 and a window as in the figure below will
open, confirming that the LI19 is connected.

Figure 5.4.1 LI19 user interface, confirming that LI19 is connected
When selecting [sensor settings], and [select sensor] select [HF03]. Select theappropriate sensitivity for the HF03 from the calibration certificate or the hand-grip. Thissensitivity will be between 0.1 and 0.7 x 10-6 V/(W/m2) and is entered as a number
between 100 to 700 in the LI19. The LI19 is now ready for use for display of the heat
flux in [ x 103 W/m2]. We suggest to make a sticker on the LI19, stating the calibration
which should appear on screen.

Figure 5.4.2 The [sensor settings] screen

HF03-LI19 manual v2020

17/25

5.4.1 Optional functionality of LI19
LI19 user interface on PC may perform several functions that are not necessarily usedwith HF03:
Setting the sensor sensitivity
Setting the data storage interval
Setting the initial delay time interval for data storage
Reading LI19 status (does not interfere with the logging process)Reading measured data (presenting a chart)
Export stored data (from the LI19 to the PC)

HF03-LI19 manual v2020

18/25

6

Maintenance and trouble shooting

6.1

Recommended maintenance and quality assurance

HF03-LI19 is typically located in hostile environments in which the sensor is underconstant threat of being damaged. Unreliable measurement results are detected byfrequent recalibration, by visual inspection of the sensor and by scientific judgement, forexample by looking for unreasonably large or small measured values.
Table 6.1.1 Recommended maintenance of HF03-LI19
MINIMUM RECOMMENDED HEAT FLUX SENSOR MAINTENANCE
INTERVALSUBJECTACTION1

before andafter every
test

inspection

inspect sensor coating, cable quality

2

after every
test

data review

judge the feasibility of the measurement data
Compare to measurements with other sensors, typically heat
flux and temperature measurements

3

after every
test

lifetime
assessment

judge if the instrument will be reliable for another test

4

every year

recalibration

recalibrate HF03 as well as LI19 at the manufacturer or a local
calibration reference

HF03-LI19 manual v2020

19/25

6.2

Trouble shooting

Table 6.2.1 Trouble shooting for HF03-LI19
GeneralSwitch the LI19 on. Look at the sensor screen
At start-up a figure between 100 and 700 should appear on screen. Check if thisfigure matches the HF03 sensitivity.
[BAT] indicates a low battery. In that case, replace batteries.
Inspect the sensor for any damage, in particular the black sensor surface.
Inspect if the wires are properly attached to the LI19.
Check the condition of the cable.
Check the LI19 program in particular if the right sensitivity is entered.
Check the electrical resistance of the sensor between the white [-] and green [+]wires. Use a multimeter at the 100 Ω range. Measure the sensor resistance firstwith one polarity, then reverse the polarity. Take the average value. Typicalresistance should be the nominal sensor resistance of 25 Ω for plus 1.5 Ω for the
total resistance of two wires (back and forth) of each 5 m. Infinite resistanceindicates a broken circuit; zero or a lower than 1 Ω resistance indicates a shortcircuit.

The sensor
does not give
any signal

Remove the white cap from the sensor.
Check if the sensor reacts to heat: use the LI19. Expose the sensor heat, forinstance by putting a flame from a consumer type gas lighter at a distance ofaround 0.01 m. The signal should read > 1 x 103 W/m2 now. Do not expose formore than 10 s.
Check the data acquisition by replacing the sensor with a spare unit.

The sensor
signal isunrealisticallyhigh or low

Check the cable condition looking for cable breaks.
Check the LI19 by applying a 1 x 10-3 V source to it. Look at the measurement
result. Check if it is as expected.
Check the LI19 by short circuiting the data acquisition input with a
10 Ω resistor. Look at the output. Check if the output is close to 0 W/m2.

The sensor
signal shows
unexpectedvariations

Check the presence of strong sources of electromagnetic radiation (radar, radio).

6.3

Recoating / repainting of sensor surfaces

ISO 14934-4 paragraph 9.1 allows repainting of sensors, according to manufacturer
recommendations. Hukseflux recommendations are:Repainting is preferably done by the manufacturer. Do-it-yourself repainting is possible
but if that is done all product warranties are cancelled.
Judge by visual inspection if the thermopile sensor is still well attached to the metal
sensor body. If not, the sensor is beyond repair. Verify sensor functionality. This canalso be done with a non-coated sensor (see the chapter of the quick sensor test). The
thermopile is then visible through its orange coloured plastic cover.
Purchase a matt (not glossy) black paint which is temperature resistant up to 600 °C.
Silicone based black paints are a good choice. Typically aerosol spray cans are most easy
to use, but such paints can also be used purchased in cans. In case a solvent is needed:
typically acetone is a good solvent for these paints.

HF03-LI19 manual v2020

20/25

Surface preparation: In case the existing sensor surface coating has small scratches but
is otherwise in good condition, do not clean, but apply new paint directly to the existing
paint. In case of heavy damage to sensor surface coatings: remove the existing coating,clean with acetone or ethanol. Lightly sand the orange plastic surface. Take care to leave
the thermopile plastic cover intact.
Paint application: the sensor surface is located in a 0.1 x 10-3 m deep locally lower
surface in the SBG01 body. Spray some paint in a small cup, use a pipette to apply the
paint. In case a pipette is not available, use a small paint brush.
Recalibration: newly coated sensors should be recalibrated. We do not expect significant(> 5 %) changes relative to the original sensitivity.

HF03-LI19 manual v2020

21/25

7

Appendices

7.1

Appendix on calibration hierarchy

HF03 factory calibration is traceable from SI through international standards and throughan internal mathematical procedure. The formal traceability of the generated heat flux isthrough a secondary standard calibration reference to the international temperature
standard ITS90. The Hukseflux SBGC method follows the recommended practice of ISO
14934-3, however we calibrate at one heat flux level only. Calibration relies on acomparison to a secondary standard heat flux sensor under a radiant heat source. HF03
is calibrated at a heat flux level of 10 x 103 W/m2.

7.2

Typical heat flux ranges

Table 7.2.1 Allowable heat flux levels in industrial environments
x 103 W/m2

Btu/hr Ft2

1

Equipment

9.5

3000

2

Human: Run

6.3

2000

3

Human: Walk

4.7

1500

4

Human: Work (static)

1.6

500

Table 7.2.2 Typical ranges of heat flux levels, from ISO 14934-4
x 103 W/m2

Comment

1

300

maximum level in a fully developed fire

2

200 to 100

incident heat flux on the wall in a developed fire enclosure

3

about 100

radiation from burning house4

about 30

causing ignition of tree

5

20 to 10

causing ignition of timber

6

about 7 or 8

lowest level for causing ignition of a timber wall under a pilot
flame

7

about 4

lowest level for causing a burn8

about 2,5highest level for people to endure

9

1,5

solar constant, maximum level of solar irradiance

7.3

Typical HF03 sensitivity

Table 7.3.1 typical sensitivity of HF03, 2015 production figures, not to be used as
reference. NOTE: in the LI19 the sensitivity is entered as a number between 100 and 700

1

MODEL

SENSITIVITY
x 10-6 V/(W/m2)

HF03

0.25 to 0.65

HF03-LI19 manual v2020

22/25

7.4

EU declaration of conformity

We,

Hukseflux Thermal Sensors B.V.
Delftechpark 31
2628 XJ Delft
The Netherlands

in accordance with the requirements of the following directive:
2014/30/EU

The Electromagnetic Compatibility Directive

hereby declare under our sole responsibility that:
Product model:
Product type:HF03-LI19
Portable heat flux sensor with read-out unit / datalogger

has been designed to comply and is in conformity with the relevant sections andapplicable requirements of the following standards:
Emission:
Immunity:

EN 61326-1: 2013
EN 61326-1: 2013

Eric HOEKSEMA
Director
Delft
March 01, 2016

HF03-LI19 manual v2020

23/25

© 2020, Hukseflux Thermal Sensors B.V.
www.hukseflux.com
Hukseflux Thermal Sensors B.V. reserves the right to change specifications without notice.