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Enabling better global research outcomes in soil, plant & environmental monitoring.

HuskeFlux LI19 Datalogger

Hand-held read-out unit / Datalogger

LI19 is a high accuracy handheld read-out unit / datalogger. It is used to make mobile measurements, for short term datalogging (as a static logger), and as an accurate millivolt amplifier directly connected to a PC. LI19 can be used with a variety of sensors. LI19’s most common application is with heat flux- and solar radiation sensors. LI19 battery life and memory allow continuous measurement for up to 50 days.

 

LI19 may be used with pyranometers and heat flux sensors

LI19 is typically used to display the measured solar radiation or heat flux. It measures a DC voltage. Once programmed with the sensitivity of the connected sensor, the display will show the actual value of the heat flux or solar radiation in W/m². LI19 is programmed through its PC user interface. We recommend downloading the latest software. LI19 is battery powered, using 2 x AA-type batteries. Fresh batteries allow more than 50 days of operation. The system is supplied in a practical transport case, for easy transport and protection during field measurement campaigns. LI19 is built for easy use with a large size LCD, displaying quantities in W/m², and a USB connection. LI19 may be used with pyranometers and heat flux sensors.

  • short-term field measurement of solar radiation or heat flux
  • amplification of heat flux sensor signals
  • education in solar energy
  • high accuracy handheld read-out unit / datalogger
  • easy transport and protection during field measurement campaigns
  • supplied in a practical transport case
  • Fresh batteries allow more than 50 days of operation

Building physics / insulation, thermal comfort and energy budget measurement

In building physics, the investigation of the insulation capabilities of building materials is an important subject of study. Hukseflux is the market leader in heat flux measurement related to building physics. The most commonly used sensor is model HFP01. Hukseflux supplies turn-key systems for analysis of thermal resistance of building envelopes and elements.

 


Application: Solar Heating in Building Automation


Insulation, thermal comfort and energy budget measurement

In building physics, the focus of measurement is on several subjects, for example:

  • analysis of indoor climate
  • studies of the insulation and thermal resistance of building envelopes
  • studies of roof reflectance
  • studies of solar transmission of glass

What is measured

Typical measurements required in such experiments, are:

  • heat flux, for example on walls
  • temperature differences over walls
  • absolute temperatures
  • solar radiation
  • net radiation

Heat flux sensors measure heat transfer. More specifically: the energy flux onto or through a surface, in [W/m²]. In reality, often this surface is the sensor itself mounted on a wall. The source of the heat flux may be:

  • conduction – heat flowing through a static, non-flowing material
  • radiation – heat transmitted, typically by visible or infra-red radiation
  • convection – heat transported by flowing fluids or gasses

Heat transfer is driven by temperature differences. Heat always flows from a source to a sink, from a hot to a cold environment.

For high–accuracy temperature difference measurement, matched sensor pairs are used; during production the accuracy of one sensor is checked relative to the other.

Pyranometers measure the radiation received by a plane surface from a 180 ° field of view angle. This quantity, expressed in W/m², is called “hemispherical” solar radiation.

In building physics most common parameters that we measure are:

  • incoming solar radiation
  • reflected solar radiation
  • roof reflectance (albedo)
  • reflectance of other components
  • solar transmission of window materials

Sensors of our pyrgeometer product line measure far infra red “longwave” radiation. The most common parameters that we measure are:

  • downwelling longwave radiation
  • upwelling solar radiation
  • roof or wall infra red “blackbody” equivalent temperature.

Two pyranometer measurements combined with two pyrgeometer measurements are used to calculate the net-radiation.

Specifications

Heat flux sensors, building envelope thermal resistance measuring systems, pyranometers, pyrgeometers and net radiation sensors must be optimised for the demands of different applications. Unique features typically required in building physics are:

  • heat flux sensors compliant with ISO 9869
  • heat flux sensors with sufficient sensitivity to measure in the 1 W/m² range
  • pyranometers suitable for roof reflectance measurement according to ASTM e1549
  • pyrgeometers measuring roof temperature over a large area
  • temperature difference measurement with an uncertainty of better than 0.1 °C over a large temperature range.

Selecting a set of sensors

We can assist you selecting a sensor. A typical checklist is:

  • what is the application; what must be measured, outdoors and indoors
  • are there any standards that you must follow
  • what are the accuracy requirements
  • how do I organise re-calibration
  • how can I mount instruments
  • what data acquisition do I have, can it measure in the millivolt range; if not what kind of input can it accept?
  • what other things must be measured; usually it is best to use one measurement system performing all measurements. Building physics experiments often have large numbers of temperature sensors. In many cased not the absolute but the relative temperature is important

What we contribute

Hukseflux provides a range of sensors and measuring systems for use in measurement of the energy budget of buildings and characterisation of construction materials. HFP01 heat flux sensor and TRSYS01 measuring system are widely used for on-site measurements on walls, windows and other construction elements. HFP01 heat flux plate is the de-facto standard for heat flux measurement on walls. In high accuracy flux measurement a typical station is equipped with two or more sensors for good spatial averaging.

Our TRSYS01 is a measuring system for analysis of the thermal resistance and the thermal transmittance of building elements by in-situ measurement.

TPSYS02 is used to characterise soils, cements and insulation materials. Our pyranometers are used to measure solar radiation on buildings and to measure solar transmission of windows and solar reflectance of roofs.

Sensors made by Hukseflux passed validation and acceptance testing for a large number of national research institutes.

Advantages

Depending on the exact requirement, we offer:

  • assistance – select the best sensors for your application
  • assistance – optimising the sensor – measuring system combination, also looking at the total system (our users often measure more than just radiation)
  • worldwide support – specialists available in the major economies
  • calibration support – efficient worldwide calibration organisation
  • proven performance – we have experience in most applications
  • traceability – formal metrological traceability to international standards

output on display

heat flux, solar radiation
Input analogue voltage
Conversion division by the sensor sensitivity
Display definition 4 digits with sign
Display refreshment rate 1 s⁻¹
Calibration uncertainty 0.1 %
Temperature dependence < 0.5 % + 3 x 10⁻⁶ V over rated range
Sample rate 2 s⁻¹
Rated input range 6.25 to 200 x 10⁻³ V (selectable)
A/D conversion 16 bits
Stored measurement definition minimum maximum and average over storage interval with conversion to W/m²
Storage capacity 3518 measurements
Storage interval range 2 to 65535 s (selectable)
Compatibility with Hukseflux sensor models LP02, HFP01, SBG01, HF03
Battery type 2 x AA
Internal power supply voltage 3 VDC
Battery life > 50 days (on fresh batteries)
Rated operating temperature range -10 to +40 °C
System requirements for use with PC Windows XP and higher
Connection to PC
USB 1.1 / 2.0 low speed
User interface on PC LI19 software
IP protection class IP40
Connection to sensor 2 x (female chassis plug for 4 mm banana with screwed signal wire clamp)
Weight 0.175 kg (net) 1.3 kg with carrying case
Dimensions LI19 (70 x 146 x 25) mm
Dimensions transport case (400 x 300 x 120) mm

Industrial monitoring and control / heat flux and heat transfer measurement

Hukseflux’ heat flux sensors can be used in industrial measurement and control systems. Examples of applications are analysis of aluminium reduction cells, detection fouling in boilers (Boiler Slagging / Fouling Sensor), monitoring of blast furnaces (Blast Furnace Safety System / General Furnace Monitoring), flame monitoring and composites processing.

Heat flux and heat transfer measurement

Many industrial systems rely on temperature measurements. Heat flux and heat transfer measurements offer additional information. A change of temperature usually goes together with a heat flux. Measuring both quantities offers a better picture of what is happening. Heat flux can often be detected earlier than a temperature change. This offers advantages, for example better process control and faster response to emergency situations.

The measurements are used for several purposes:

  • Process monitoring: Creating a performance baseline
  • System protection: detection of failures in cooling systems
  • System energy efficiency: detection of wear of insulating layers
  • Process monitoring: detection of deposition of fouling
  • Personnel safety: measurement of heat stress by radiation
  • Energy efficiency: studies of insulation / thermal resistance

What is measured

Heat flux sensors measure heat transfer. More specifically: the energy flux onto or through a surface, in [W/m²]. In reality this surface is the sensor itself. The source of the heat flux may be:

  • conduction – heat flowing through a static, not-flowing material
  • radiation – heat transmitted, typically by visible or infra-red, radiation
  • convection – heat transported by flowing fluids or gasses

Heat transfer is driven by temperature differences. Heat always flows from a source to a sink, from a hot to a cold environment.

Convective and conductive heat fluxes are measured by letting this heat flow through a heat flux sensor. Heat flux sensors are either mounted on a surface of a solid object or embedded into this object. Measuring convective heat flux, the sensor will typically be located on the surface of a solid object, and exposed to the convective flow; at the sensor surface, the convective flux is then converted into a conductive flux.

Radiative flux is measured using a heat flux sensor covered with a (black) radiation absorber. It is usually mounted on a solid, well conducting heat sink. The absorber converts radiative energy to conductive energy.

At the surface of a solid object, often the source of heat flux is a mixture of radiative and contributions.

Heat flux measurement is typically combined with temperature measurement. Relative to conventional monitoring based on temperature, use of heat flux sensors improves insight in processes and often leads to faster response times for process control and emergency response.

Specifications

Some heat flux sensor models, we call these “self-calibrating”, have integrated heaters, so that the user may perform on-site performance checks. This is useful if sensors cannot be removed, or can only be removed at high cost.

Heat flux sensors manufactured by Hukseflux are optimised for the demands of different applications:

  • rated temperature range; we make sensor for use from -150 to + 900 °C
  • rated heat flux range; from 0.01 to 200 000 W/m²
  • sensitivity / output signal
  • response time
  • chemical resistance, safety requirements; including sensors for potentially explosive environments
  • size, shape and spectral properties
  • optional on-site performance validation or self-calibration capabilities

Products are manufactured under ISO 9001 quality management system. If applicable, the sensors comply with industrial standards such as ITS90, ANSI, DIN, and BS. Sensors for hazardous areas can be manufactured according to safety standards like EExi, ATEX / Cenelec and NAMUR.

Selecting a sensor

We can assist you selecting a sensor. For preparation, please read:

  • our note about general things to keep in mind when measuring heat flux, also showing different sensor models and their most common applications

also note:

  • some measurements are standardized like those for building thermal resistance, flammability testing; you have no choice what procedure to follow
  • with many applications you will find a dedicated model

a typical checklist is:

  • what is the application, what must be measured
  • are there any standard that you must follow
  • any requirements for size and shape
  • what are the accuracy requirements
  • how do I organise re-calibration; do we need on-site performance validation or self-calibration capabilities
  • how can I mount the sensor
  • what is the rated temperature range in °C
  • what is the rated heat flux range in W/m²
  • what data acquisition do I have, can it measure in the millivolt range; if not what kind of input can it accept?
  • what other things must be measured; usually it is best to use one measurement system performing all measurements
  • any special requirements for example response time, spectral properties, ..
  • any special environmental conditions, requiring chemical resistance, protection against water or dust, approvals for Ex safety, approvals for potentially explosive environments
  • what is the required cable length

What we contribute

Hukseflux company started in 1993 making sensors for measurement of heat flux in soils and on walls. In the course of the years, we have added many “special purpose” sensors and systems for other applications. We have designed and supplied sensors for many industrial projects. Our experience includes a variety of environments such as coal fired boilers, fluidised beds, solar concentrators, offshore flare systems and blast furnaces. We are the market leader in industrial heat flux and heat transfer measurement.

Advantages

Hukseflux is the world market leader in heat flux measurement. We offer:

  • assistance – select the best sensor for your application
  • assistance – optimising the sensor – measuring system combination, also looking at the total system (our users often measure more than just heat flux)
  • worldwide support – specialists available in the major economies
  • proven performance – in most applications we have experience
  • proper certification – CE, ATEX, ASME approvals
  • traceability – formal metrological traceability to international standards.