HFM 446 Lambda Eco-Line

Heat Flow Meter

Saving and Efficient use of Energy

Never before has the topic of the saving and efficient use of energy attracted as much attention in economics and politics around the globe as it does today. Research and development efforts in industry and academia worldwide are addressing topics that contribute to saving energy or generating energy from alternative resources.

There is enormous potential, especially in the areas of insulation materials and the efficient thermal insulation of residential and commercial buildings. It is thus all the more important for insulating materials to be able to be manufactured with a high and steady level of quality and brought onto the market under strict control of their performance characteristics.

There are numerous standards and guidelines to which these products are subject in order to really guarantee these properties for the huge amounts of insulating materials being produced worldwide.

Our latest version, the HFM 446 Lambda Eco-Line, also makes sure that the highest level of energy efficiency is at work when measuring thermal conductivity.

Material Parameter Thermal Conductivity

The most important role here is played by the material parameter thermal conductivity (amount of heat per second flowing through a material layer of a thickness of 1 meter and an area of 1 m² when the temperature difference amounts to 1 K). The thicker the material layer through which the heat flows, the higher the thermal resistance (R-Value) that the material layer presents to the quantity of heat to be transported. The reciprocal value of the thermal resistance is the thermal transmittance (U-Value), usually specified for structural components.

No matter whether for expanded polystyrene (EPS), extruded polystyrene (XPS), PU rigid foam, mineral wool, bloated perlite or foam glass, cork, fleece or natural fiber materials – no matter whether for building materials containing phase change materials, aerogels, concrete, plaster or polymers or even high performing insulation materials like vacuum insulation panels (VIP's) – the new HFM 446 Lambda Eco-Line features a new standardized method for the measurement of thermal conductivity which is equally applicable in research and development and in quality assurance.

A temperature gradient is set between two plates through the material to be measured. By means of two highly accurate heat-flow sensors in the plates, the heat flow into the material and out of the material, respectively, is measured. If the state of equilibrium of the system is reached and the heat flow is constant, the thermal conductivity can be calculated with the help of the Fourier equation as long as the measurement area and thickness of the sample are known.



  • Thermal Conductivity Measurements
    On insulating materials, polymers, phase-change materials, aerogels, non-wovens and many more (not with the HFM Large)
  • Based on Standards
    ASTM C518
    ISO 8301
    DIN EN 12664 (not HFM Large)
    DIN EN 12667
    JIS A1412
  • Two Ways of Measurement
    • Connected with a computer and the unmatched new SmartMode software
    • Simple use of stand-alone instrument with integrated printer
  • Easy and fast set up
    Factory calibrated with certified reference materials (IRMM 440 and NIST SRM 1450d)
  • Fast Measurements
    Up to 40% faster measurements than previous versions
  • New Eco-Mode
    for reduced energy consumption
  • Best Test Conditions
    Closed test chamber minimizes influence of the environment and reduces condensation risks
  • Innovative Sample Thickness and Parallelism Measurement
    By two-axis inclinometer
  • High Throughput
    Fast sample change due to motorized plate and door movement minimize disturbances on the plate temperatures
  • From Lower to Higher Conductivities
    The use of external thermocouples extend the thermal conductivity range to a higher level
  • “Drive- to-thickness” Feature
    Variable external load for precise measurements on compressible materials and thus density of compressible materials
  • Increased accuracy
    Possibility to combine single heat flux calibrations using HFT (Heat Flux Transducer) MultiCalibration
  • No Waste of Time
    Complete QA-Documentation including Lambda 90/90-calculation and determination of Equivalent Thermal Conductivity just a click away 
  • Compliance to standards made easy
    with Stability Configuration Management
  • Improved instrument handling
    through new User Interface
  • Works everywhere for everyone
    Multiple operating systems - multiple languages
  • Measurement of specific heat capacity (cp)
    Based on step method

Key Technical Data

Key Technical Data

(subject to change)

  • Type:
    Stand-alone, with integrated printer
  • Air-tight system:
    Sample compartment with possibility to introduce purge gas
  • Motorized plate:
  • Thermal conductivity range:
    • Small: 0.007 to 2.0 W/(m·K)
    • Medium: 0.002 to 2.0 W/(m·K)
    • Large: 0.001 to 0.5 W/(m·K)
      Small and Medium: 2.0 W/(m·K) achievable with optional instrumentation kit, recommended for hard materials and those with higher thermal conductivity
    • Accuracy: ± 1% to 2%
    • Repeatability: ±0.25%
    • Reproducibility: ± 0.5%
      → All performance data is verified with NIST SRM 1450 D (thickness 25 mm)
  • Plate temperature range:
    -20°C to 90°C (optional for Medium: -30°C to 90°C)
  • Metering area heat flux transducer:
    • Small/Medium: 102 mm x 102 mm
    • Large: 254 mm x 254 mm
  • Chiller system:
    External; constant temperature setpoint over plate temperature range
  • Plate temperature control:
    Peltier system
  • Plate motion:
  • Plate thermocouples:
    Three thermocouples on each plate, type K (two extra thermocouples with instrumentation kit)
  • Thermocouple resolution:
    ± 0.01°C
  • Number of setpoints:
    Up to 99
  • Specimen sizes:
    • Small: 203 mm x 203 mm x 51 mm
    • Medium: 305 mm x 305 mm x 105 mm
    • Large: 611 mm x 611 mm x 200 mm
  • Variable load/ contact force:
    • Small: 0 to 854 N (21 kPa on 203 x 203 mm²)
    • Medium: 0 to 1930 N (21 kPa on 305 x 305 mm²)
    • Large: 0 to 1900 N (5 kPa on 611 x 611 mm²)
      Precise load control and possibility to vary density of compressible materials; contact pressure calculated by software based on load sensor signal
  • Thickness determination:
    • Automatic measurement of mean sample thickness
    • Four-corner thickness determination via inclinometer
    • Compliance to non-parallel specimen surfaces
  • Software features:
    • SmartMode (incl. AutoCalibration, report generation, data export, wizards, user methods, predefined instrument parameters, user-defined parameters, Cp determination, etc.
    • Storage and restoration of calibration and measurement files
    • λ90/90 Report
    • Plot of plate/mean temperatures and thermal conductivity values
    • Monitoring of heat flux transducer signal
    • Creation/selection of configurations for stand-alone-operation (without PC)


Advanced Insulation Testing using the Standardized Heat Flow Meter and Guarded Hot Plate Techniquesmp4
Talking to the experts Efficient determination of thermal conductivity on insulation materials



Method and Technique for the Characterization of Insulation Materials

Application literature

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