Heat Flow Meter and
Guarded Heat Flow Meter

Heat Flow Meter (HFM) and Guarded Heat Flow Meter (GHFM) Technology by NETZSCH

The Heat Flow Meter (HFM) method determines the Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.thermal conductivity of materials by applying a steady-state heat transfer method. It is particularly effective for testing low-conductivity materials such as insulations. The system measures the heat flux across a specimen placed between two plates with a known temperature gradient.

The Guarded Heat Flow Meter (GHFM) method involves placing a specimen between two plates controlled at different temperatures. Multiple RTD sensors measure the temperatures on each side, while heat flux sensors measure the heat flow caused by the temperature gradient. To prevent lateral heat loss, an active guard is incorporated.

With the LFA, GHP, GHFM, and HFM thermal analysis methods, NETZSCH offers a comprehensive portfolio for the measurement of Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.thermal conductivity - one of the key thermophysical properties, along with thermal expansion and Specific Heat Capacity (cp)Heat capacity is a material-specific physical quantity, determined by the amount of heat supplied to specimen, divided by the resulting temperature increase. The specific heat capacity is related to a unit mass of the specimen.specific heat capacity. This allows for precise and reliable characterization of a wide range of materials across different temperature ranges and applications.

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Our Heat Flow Meters and Guarded Heat Flow Meter

Explore the range of NETZSCH HFM and GHFM instruments

HFM 706 Lambda Small
An exact, fast and easy-to-use instrument for measuring the low Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.thermal conductivity, λ, of insulation materials.
- Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature. Thermal conductivity range: 0.007 to 2 W/(m·K)
- Metering area heat flux transducer: 102 mm x 102 mm
- Specimen sizes (max.): 203 mm x 203 mm x 51 mm
HFM 706 Lambda Medium
An exact, fast and easy-to-use instrument for measuring the low Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.thermal conductivity, λ, of insulation materials.
- Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature. Thermal conductivity range: 0.002 to 2 W/(m·K)
- Metering area heat flux transducer: 102 mm x 102 mm
- Specimen sizes (max.): 305 mm x 305 mm x 105 mm
HFM 706 Lambda Large
An exact, fast and easy-to-use instrument for measuring the low Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.thermal conductivity, λ, of insulation materials.
- Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature. Thermal conductivity range: 0.001 to 0.5 W/(m·K)
- Metering area heat flux transducer: 254 mm x 254 mm
- Specimen sizes (max.): 611 mm x 611 mm x 200 mm
HFM 446 Lambda Small Eco-Line
An exact, fast and easy-to-use instrument for measuring the low thermal conductivity, λ, of insulation materials.
- Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature. Thermal conductivity range: 0.007 to 2 W/(m·K)
- Metering area heat flux transducer: 102 mm x 102 mm
- Specimen sizes (max.): 203 mm x 203 mm x 51 mm
TCT 716 Lambda
Determine the thermal conductivity of round solid specimens in the low- and medium-conductivity range with our Guarded Heat Flow Meter:
- Sample mean temperature range: -10°C to 300°C
- Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature. Thermal conductivity range: 0.1 … approx. 30 W/(m·K)
- Two independent test stacks to measure two samples at the same time

About the Methods

Thermal resistance and thermal conductivity are critical parameters in determining whether a material is an insulator or a good heat conductor. These properties are essential when designing thermal management systems to prevent overheating and improve energy efficiency. Depending on the application and material, there are different methods to measure and evaluate these properties.

With the combination of LFA, GHP, GHFM and HFM, NETZSCH offers a complete range of analysis instruments for characterizing thermal conductivity. Please feel free to contact our NETZSCH experts to choose the most suitable measuring method for your specific needs.

Heat Flow Meter Technology: For thermal insulating materials with low thermal conductivity

In this method, a sample of the material with known dimensions is placed between two plates of different temperatures. One plate is heated, while the other is cooled, creating a temperature gradient across the material. Heat flows through the sample from the hot plate to the cold plate. The rate of heat transfer (heat flux) and the temperature difference across the sample are measured.

Using Fourier's law of heat conduction, which relates the heat flux, temperature gradient, and thermal conductivity of the material, the thermal conductivity of the sample can be calculated.

Guarded Heat Flow Meter Technology:
For medium-conductivity materials

The Guarded Heat Flow Meter (GHFM) method involves placing a specimen between two plates controlled at different temperatures. Multiple RTD sensors measure the temperature on each side, while heat flux sensors measure the heat flow caused by the temperature gradient. To prevent lateral heat loss an active guard is incorporated.

This design allows for high accuracy and repeatability by measuring thermal conductivities in the medium range with accordance to ASTM E1530.

Figure: GHFM schematic (with two independent test stacks)

What Makes these NETZSCH Instruments Unique?

Precision and Accuracy: Our advanced sensor technologies provide superior measurement precision. NETZSCH Instruments feature high spatial and temporal resolution for consistent results.
Ease of Use: Fully automated workflows reduce manual intervention. Moreover, the intuitive software interfaces simplify operation and data interpretation.
Robustness and Reliability: We offer long-term durability for continuous use in lab and industrial environments and highly stable measurements even under demanding conditions.
Compliance and Validation: NETZSCH HFM and GHFM instruments are fully compliant with major industry standards, ensuring the validity of results for certifications and quality control.
Customized and Integrated Solutions: NETZSCHs’ wide range of testing instruments, covering a broad thermal conductivity application range, ensures that we meet your thermal analysis demands for a variety of materials and temperature ranges.
Proven Excellence: Decades of experience in thermal analysis and a strong reputation for innovation and quality emphasize the reliability and advanced capabilities of NETZSCH analysis instruments.

Long Instrument Life

High-quality instrument paired with long spare part availability and best service

Always there for you

Direct contact to your NETZSCH experts from service, lab, training and sales

Proven Excellence in Service

We support your NETZSCH instrument through the entire life cycle

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Over25

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instruments for thermal conductivity testing tailored to your application

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Thin film ribbon cable thermal conductivity testing

Saving and Efficient Use of Energy

Today, the need to save energy and use it efficiently has become a global priority. Insulation materials and thermal efficiency in buildings play a crucial role in reducing energy consumption, making their quality and performance a key focus.

Both the NETZSCH HFM Eco-Line series and the TCT 716 Lambda are of course optimized too for energy-efficient operation ensuring minimal energy usage during thermal conductivity testing.

HFM and GHFM Applications

Accurate measurement of the thermal conductivity of insulation and engineering materials is essential for energy-efficient product design. NETZSCH Analyzing & Testing offers two advanced methods: the Heat Flow Meter (HFM) for routine insulation testing and the Guarded Heat Flow Meter (GHFM) – the TCT 716 Lambda – for high-precision measurements with active guard technology across a broader temperature and material range.

Application Areas for NETZSCH Heat Flow Meters (HFM)

NETZSCH HFM instruments are first choice for routine and quality control testing of low thermal conductivity materials. With a mean sample temperature range from -20°C to 90°C, they are ideal for:

Building and construction insulation: Expanded and extruded polystyrene (EPS/XPS), polyurethane (PU) and polyisocyanurate (PIR) foams as well as mineral wool and natural fiber mats
Natural insulation materials: Hemp, cork, cellulose
Aerogels and vacuum insulated panels (VIP)
Appliance insulation: e.g. Refrigerator/freezer panels
Automotive applications: Interior thermal barriers and insulation foams

Application Areas for NETZSCH Guarded Heat Flow Meters (GHFM)

The TCT 716 Lambda is NETZSCH’s Guarded Heat Flow Meter – a high-precision instrument based on the steady-state method with an actively controlled guard to minimize lateral heat loss and enhance accuracy. It operates from -10°C to 300°C, making it ideal for testing in the low- and medium-conductive range:

Polymers, filled and unfilled
Fiber-reinforced polymers (anisotropic)
Glasses
Low-conductive metals like stainless steel, Ni-based alloys
Ceramics and refractories (inhomogeneous)
Building materials like concrete and cement

"We purchased our Heat Flow Meter already in 2002 and still use it to measure the thermal performance of extruded polystyrene."
URSA Insulation Materials
Agrate Brianza, Italy

"NETZSCH performs contract testing measurement with the HFM to determine the thermal conductivity of our nonwovens."
Sandler AG
Schwarzenbach an der Saale, Germany

"The HFM method is applied to evaluate_{Specific Heat Capacity (cp)Heat capacity is a material-specific physical quantity, determined by the amount of heat supplied to specimen, divided by the resulting temperature increase. The specific heat capacity is related to a unit mass of the specimen.cp}(T) and_λeff(T) of a lithium-ion pouch cell perpendicular to the pouch surface at a different state of charge."
Center for Energy at AIT Austrian Institute of Technology GmbH
Vienna, Austria

HFM Case Studies

Governments are imposing strict building insulation regulations to reduce carbon emissions. As a result, much effort is being put into developing materials with very low thermal conductivity to provide the market with even better thermal insulation materials.

Learn how the NETZSCH HFM can help in this and many other application areas!

See all Customer Success Stories