Hukseflux

Thermal Sensors

HF02

Flare radiation monitor / heat flux sensor
HF02 is a sensor that measures radiant heat flux or thermal radiation in the outdoor environment. A
common application is monitoring the radiation emitted by flares. HF02 is certified for use in potentiallyexplosive atmospheres, and is rated for radiation levels up to 15 x 103 W/m2. We recommend use of HF02
in a decision-supporting role only, and not to use measurements of HF02 as the main or sole source ofinformation for judging safety.

Introduction
HF02 is used in alarm systems, using the heat
flux measurement to issue a warning in case ofhigh thermal radiation exposure of equipment orpersonnel. It is typically installed close to a flare.
A common assumption is that the heat flux levelin a safe environment for personnel must notexceed 5 x 103 W/m2 (or 1.5 x 103 BTU/(hr∙ft2)).
Above that heat flux level, or when thetemperature of the sensor body exceeds 70 °C,
an alarm is activated. A typical alarm system will
include multiple HF02 sensors, all aimed at themain source of radiation, as well as otherdecision-supporting devices such as camera
systems and temperature sensors.

Figure 1 HF02 flare radiation monitor / heat flux sensor

90105121344659231130

Figure 2 HF02 consists of a heat flux sensor (1)providing both a heat flux and a sensor bodytemperature measurement, a sensor body (3), aradiation shield (2) and rain screen (10) to protect thesensor against the environment, a high-temperature
metal sheathed cable (4), a cable transition piece (5), alow temperature extension cable (6), mounting holes(3/8 UNC) (9) and spacers (11). The transition piece (5)to the cable end (at 7) in area 8 must be between -20
and +70 °C, and the cable end (at 7) must be provided
by the user with an enclosure certified for use in the areaof installation. Installation is the responsibility of theuser. Dimensions in x 10-3 m.

87

The sensor in HF02 measures the heat flux to its
black (absorbing) surface, in the plane of thesensor, from a source in the field of view angle.
It offers a measurement of the effective exposurefor personnel and equipment from a source in thedirection it is aimed at the location of the sensor.
As the detector is essentially open (it has noprotective windows) the measurement isinfluenced by wind in the same way as any
exposed surface such as clothing worn bypersonnel or the surface of equipment; increased
wind speed leads to a reduction of the measured
heat flux. Rain on the detector can also lead tocooling and a reduction of the measured heat flux.

Copyright by Hukseflux. Version 2110. We reserve the right to change specifications without prior notice
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Hukseflux

Thermal Sensors

To perform a heat flux measurement
representative of human exposure or equipment
exposure, the sensor temperature should be as
close as possible to the ambient air temperature.
This is the purpose of the sun / rain- andradiation screens of HF02 (in combination withcooling fins). They reduce radiative heating of thesensor by the sun. The screens also reduce theeffect of wind and rain, reducing the risk of afalse indication of a safe situation.
HF02 is rated for use in potentially explosiveenvironments. It is supplied with a productcertificate specifying the ATEX rating II 2G Ex db
IIC T6.
Using HF02 is easy. It can be connected directly
to commonly used data logging systems. The
heat flux in W/m2 is calculated by dividing theHF02 output, a small voltage, by the sensitivity.
The sensitivity is provided with HF02 on its
product certificate.
The sensor body temperature is monitored as aredundant safety precaution. In case the sensorhas a temperature above a specified level,
typically 70 °C, we recommend to consider this asign that there are strong local heat sources andto issue a warning.

HF02 specifications
Model name according toEU type examination
Measurands
Heat flux sensor
Temperature sensor
Measurement range
Sensitivity (nominal)
EC type examination certificate
ATEX rated operating conditions
Electrical datarobustall-weather
suitable for potentially explosive
environments

Suggested use•

outdoor flare monitoring

Maintenance and calibration
HF02 should be regularly inspected.
The sensor performance can be verified bycomparison to a portable heat flux sensor such asmodel HF03.

See also•••

view our complete line of heat flux sensors
SBG01 for high-accuracy indoor heat flux
flame measurement
view portable heat flux sensors type HF03
(for calibration and performance verificationof HF02)

heat flux
sensor temperaturethermopile
thermocouple type KX
0 to 15 x 103 W/m2
-30 to + 100 °C
0.3 x 10-6 V/(W/m2)
included in delivery
II 2G Ex db IIC T6Umax 5 V,Imax 5 x 10-3 A-50 to +300 oCRated process temperature range
sensor and high temperature cable
Rated operating temperature range -20 to +70 oC
transition piece, low temperatureextension cable and cable end
Standard cable lengths:
High temperature cable
3 m(see options)
Low temperature extension cable
3 m (see options)
IP protection class:Sensor and high temperature cable IP68
Low temperature extension cable
IP67
Safety notes
see manual
Maintenance requirements
see manual

Options•

Advantages•••

LEX30••

longer cable: standard length of the hightemperature metal sheathed cable as well as
the low temperature extension cable is 3 m.
Both can be extended up to 100 m.
sensitivity: we offer dedicated converters for
HF02 to provide a standardised output
shielding options: the standard version has
the sensor body and the high temperature
cable connected to the shield/drain wire of
the low temperature plastic cable. A shielddisconnected from the high temperature
metal cable and sensor body is offered as anoption.

About Hukseflux
Hukseflux Thermal Sensors makes sensors andmeasuring systems. Our main area of expertise ismeasurement of heat transfer and thermal
quantities such as solar radiation, heat flux andthermal conductivity. Hukseflux products andservices are offered worldwide via our office inDelft, the Netherlands and local distributors.

Interested in this product?
E-mail us at: info@hukseflux.com

Copyright by Hukseflux. Version 2110. We reserve the right to change specifications without prior notice
Page 2/2. For Hukseflux Thermal Sensors go to www.hukseflux.com or e-mail us: info@hukseflux.com