Guarded Hot Plate/Guarded Hot Pipe
Guarded Hot Plate (GHP) and Guarded Hot Pipe (TLR) Technology by NETZSCH
With these technologies, NETZSCH offers state-of-the-art instruments for measuring 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 building, construction and insulating materials. GHP (guarded hot plate) devices are in accordance with ISO 8302; TLR (guarded hot pipe) devices are in accordance with DIN EN ISO 8497.
These NETZSCH instruments provide highly accurate, absolute measurements 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 and thermal resistance, as well as a calculated U-value for materials with low conductivity.
With the combination of GHP, LFA, GHFM and HFM, 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. Please feel free to consult with our NETZSCH experts to choose the best-suited measuring method for your specific needs.
Our Guarded Hot Plates/Pipes
Explore the range of NETZSCH GHP and TLR instruments
About the Method
Guarded Hot Plate – The Absolute Method for Testing Insulation Materials
Guarded Hot Plate – Principle of Operation
In the plate apparatus, the heat flow is determined by measuring the power consumption of the heating plate for a defined measurement section.
There are two versions of a guarded hot plate (GHP):
On the one hand, there is the single-plate instrument with only one test specimen and the double-plate device with a central heating plate and two test specimens on the other.
In the single-specimen instrument (see figure 1), one of the test specimens is replaced by a combination of an insulating material and a counter heating plate. A temperature difference of zero is then regulated between the actual heating plate and the counter heating plate using a special thermal chain. This enables perfect measurement of a test specimen using the direct measurement method.
In the two-plate method (see figure 2), the sample is located between the heating and cooling plates. However, according to EN 12667, the samples must be almost identical, which is challenging for many applications. For this reason, most customers prefer the single-specimen measurement method.
Definition of Thermal Conductivity
Thermal 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.
According to the second law of thermodynamics, heat always flows in the direction of the lower temperature. The relationship between transported heat per unit of time (dQ/dt or heat flow · Q) and the temperature gradient (ΔT/Δx) through Area A (the area through which the heat is flowing perpendicularly at a steady rate) is described by 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 equation.
Thermal conductivity is thus a material-specific property used for characterizing steady heat transport.
What Makes NETZSCH GHP Instruments Unique?
- Absolute measurement method: Only the specifications of dimension, temperature and electrical power are required, i.e., no calibration or correction is necessary.
- Great Flexibility: Different sizes of metering sections are possible with a sample thickness of 15 to 380 mm (depending on the material); benefit also from the rotatable measuring chamber available (0 – 90°; available for GHP 800/ 900 S)
- Broad Measurement Range: Large 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 up to 2.0 W/(m·K) (depending on the material and thickness) suitable for super-insulating materials as well as higher-conductivity
- Flexible Sample Configuration: Available in 1- or 2-specimen measurement modes (per ISO 8302) – giving users the choice to simultaneously test a single sample against a reference or two identical samples. A motorized upper plate makes it easy to switch configurations and insert samples.
- Automated Operation: Universal software program with intuitive touchscreen interface and automatic contact force, pressure determination and thickness measurement
- Compliance and Validation: NETZSCH GHP instruments are universally applicable for insulation and building materials and 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 covers a broad thermal conductivity application range, ensuring that we can meet your thermal analysis demands for a wide range of materials and temperature ranges.
- Proven Excellence: Decades of experience in thermal analysis and a strong reputation for innovation underline the reliability and advanced capabilities of NETZSCH analysis instruments.
Frequently Asked Questions
This is a list of questions, that can be answered with this method. Of course, there are many more.
- How is a particular insulation material performing?
- How can cryo-tanks be insulated the best possible way?
- Does cryogenic insulation reliably prevent heat exchange?
- What is the optimum insulation for furnaces operating under different temperature, gas or pressure conditions?
- Is the thermal conductivity low enough to prevent thermal bridges?
Whenever traceability and adherence to ISO 8302 or EN 12667 are required for an insulating material’s thermal conductivity, the NETZSCH GHP is the go-to choice.
NETZSCH's Guarded Hot Plate (GHP) instruments provide highly accurate and precise measurements of the thermal conductivity, thermal resistance, and resulting U-values for low-conductivity materials. In accordance with ISO 8302 and ASTM C177, the GHP 500/600/900/900S devices are ideal for research, development, and quality control in the insulation industry and beyond as the reference method.
However, the GHP models differ in sample size, test chamber accessibility, and intended use. The GHP 500/600/900 models are ideal for medium to large samples; GHP 900 S adds tilting functionality; and the GHP 456 Titan® is a compact option for small samples with the possibility to choose between a low‐temperature version (‐160°C to 250°C) and the high‐temperature version (‐160°C to 600°C).
Please find here the detailled differentation:
GHP 500
- Sample size up to 500 x 500 mm
- Heating area: 200–300 mm
- Sample thickness: up to 200 mm
- Plate temperature range: -15°C to +70°C
- Ideal for standard insulation materials in labs and QC
GHP 600
- Sample size up to 600 x 600 mm
- Same heating area and temperature range as GHP 500
- Increased capacity for larger insulation panels
GHP 900
- Sample size up to 900 x 900 mm
- Heating area: 200–500 mm
- Sample thickness: up to 280 mm
- Designed for large and heavy specimens
GHP 900 S
- Same technical specifications as GHP 900
- Additional tiltable test chamber for angled sample measurements (e.g., glazing units)
Please feel free to consult with our NETZSCH experts to choose the best-suited GHP model for your specific needs.
The great advantage of the GHP method is that it is an absolute method; i.e., no calibration or correction is required at all. The thermal conductivity values result in the stationary state simply from the:
- precisely measured total power input into the hot plate, Q,
- average sample thickness, d,
- measurement area, A, and
- mean temperature difference, ΔT, along the sample or the two samples, as the case may be (the factor 2 results for two samples):
The GHP method is described in, e.g., ISO 8302, ASTM C177 or DIN EN 12667.
Yes. All GHP 500/600/900 models feature cooling and heating plates, enabling tests from -15°C to +70°C depending on the configuration.
The GHP 456 Titan® is available for a temperature range from -160 to 250°C (low-temperature version) or -160 to 600°C (high-temperature version).
NETZSCH GHP instruments can measure materials with thermal conductivities as low as 0.005 W/(m·K), making them ideal for high-performance insulators like VIPs and aerogels.
Yes. Our touchscreen and Windows-based Lambda software offer intuitive setup, automated measurement sequences, and comprehensive data analysis.
No, the GHP method is absolute and does not require calibration standards for each measurement.
The key difference between thermal conductivity and thermal resistance lies in what they describe and how they are measured:
- Definition: It is a material property that quantifies how well a material conducts heat.
- Unit: Measured in W/m·K (watts per meter per kelvin).
Key Concept:- A high thermal conductivity means heat flows easily through the material (e.g., metals like copper or aluminum).
- A low thermal conductivity indicates the material is a good thermal insulator (e.g., insulation materials, VIPs (Vacuum Insulation Panels), ceramics, polymers).
- Definition: It quantifies how effectively a material or system resists the heat flow. It is not a material property but depends on the geometry and thickness of the material.
- Unit: Measured in K/W (kelvin per watt).
- Key Concept:
- High thermal resistance means the material or system effectively resists the heat flow. (good insulator).
- Low thermal resistance indicates efficient heat transfer (good conductor).
Visit also our glossary to learn more:
The cost of a NETZSCH Guarded Hot Plate or Guarded Hot Pipe can significantly vary depending on the model, features, and any additional accessories or software options you may require.
To get an accurate and up-to-date price for your individual NETZSCH GHP Instrument, please contact your local NETZSCH representative or one of our authorized distributors. We will provide a quote tailored to your specific requirements, including any necessary training, installation, or additional features.
Our current delivery time is approximately 8-12 weeks, depending on the specific configuration of the GHP and current demand. For more complex customizations or during periods of high demand, the delivery time may extend beyond this range.
For the most up-to-date information, we encourage you to contact us directly with a specific request. This will ensure that we can provide you with an accurate timeline tailored to your specific needs.
Your Benefits
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NETZSCH GHP Applications
NETZSCH GHP instruments are utilized across various industries and research fields wherever thermal insulation performance must be quantified with high accuracy. Key application areas include:
- Building & Construction Materials: Determining the thermal conductivity (λ value) of insulation boards (EPS/XPS foams, mineral wool, fiberglass), wall panels, brick composites, roofing materials, and other building envelope components. The GHP method’s absolute accuracy is critical for certifying products to meet energy efficiency regulations (U-value calculations for walls, etc.).
- Vacuum Insulation Panels (VIPs): Precise measurement of ultra-low conductivity vacuum panels and aerogel blankets used in high-performance building insulation and cold-chain logistics. GHP 500/600/900 can directly and confidently measure VIPs’ extremely low λ, which is essential for quality control and product development in this cutting-edge insulation technology.
- Aerogels and Advanced Insulation Materials: Characterizing novel nano-porous insulators (silica aerogels, polymer aerogels, etc.) and high-performance composites. The GHP’s ability to test across a range of mean temperatures is useful for understanding how these materials perform in different climate conditions.
- Industrial Process Insulation: Evaluation of insulating materials used in industrial equipment, pipelines, and process plants such as calcium silicate boards, high-temperature insulation wool, or microporous panels. The GHP 900’s large sample area supports reliable thermal conductivity testing of full-size industrial insulation products. For temperatures above 100 °C, other NETZSCH instruments like the TCT or HFM may complement the GHP.
- Research and Standards Laboratories: National labs and certification institutes (e.g., building material test labs) use NETZSCH GHPs as reference instruments for round-robin tests and standards verfication. Their absolute measurement (without the need for calibration of a reference material in each run) and compliance with ISO/ASTM make them the gold standard.
Absolute and Highly Accurate!
NETZSCH Guarded Hot Plate (GHP) instruments deliver absolute and highly accurate measurements of thermal conductivity (λ) and thermal resistance (R-value) for low-conductivity materials. These values form the basis for U-value calculations.
Whenever traceability and full compliance with ISO 8302 or EN 12667 is required, NETZSCH GHP instruments are the the go-to choice.
Media and Training
Application Literature about GHP and TLR
Blog articles about GHP and TLR
- 21.01.2026
The Guarded-Hot-Plate Method: How Gas Type and Pressure Can Change the Thermal Conductivity of Your Insulation Materials
- 28.05.2025
Contract Testing of Thermophysical Properties – Enhanced with the NETZSCH TCT 716 Lambda Guarded Heat Flow Meter
- 21.11.2024
Measuring Thermophysical Properties with Focus on Thermal Conductivity
- 07.08.2024
The NETZSCH TCT 716 Lambda: Guarded Heat Flow Meter for Direct Measurement of the Thermal Conductivity
- 13.03.2024
Cracow University of Technology Relies on NETZSCH Analysis Instruments
- 07.07.2022
60 Years of NETZSCH-Geraetebau: The History of Heat Flow Meters
Videos that may be interesting for you
FAQs about NETZSCH GHP/TLR Service
Our NETZSCH applications laboratory is providing contract testing services for a wide range of industries and research centers. It is equipped with state-of-the-art GHP testing instruments allowing for a variety of thermophysical property measurements to be carried out.
Whether you're benchmarking insulation materials, evaluating composites, or developing thermal interface materials, our professional laboratory offers access to cutting-edge instruments and expert support — without the need for in-house equipment.
Consult the NETZSCH experts in our applications labs to choose the best-suited measuring method for your specific needs. You will be working with our experienced scientists (physicists, chemists, materials scientists), possessing consolidated knowledge of the most varied methods and materials spectra.
We offer:
- Installation and Commissioning
- Relocation of your instrument
- Maintenance and inspection
- Calibration
- Repair
- Comprehensive training from basic to advanced use of the instrument - on-site and online.
Please note that our service may vary from region to region.
Our Remote Service is available worldwide.
Yes, we offer maintenance contracts for your instruments according to the different regional and individual customer requirements. Please feel free to contact our Service Department or take a closer look at our website section Service-Level Agreement - NETZSCH Analyzing & Testing.
Thanks to the integrated single board computer (SBC) with Windows operating system, the Lambda software and the high-resolution color touch display, the devices are very user-friendly. Data acquisition, processing, and control are thus easily handled. Download our brochure to learn more:
Benefit from our free e-learning basic courses:
Our basic e-learning courses are available free of charge on our website, designed to support you exactly where learning really happens: in everyday lab work. Whether you’re new to thermal analysis, rheology, or fire testing or simply want to refresh your knowledge: Our expert-led video courses help you:
✔ start measurements with confidence
✔ understand results correctly
✔ reduce operator errors
✔ save time searching for solutions
All courses are created by NETZSCH experts with decades of hands-on experience, sharing real knowledge you can directly apply in the lab.
👉 Start learning for free:netzs.ch/e-learning
Moreover, we offer
- online training via our NETZSCH Online Academy NOA,
- 1:1 remote training and
- on-site training at your location or our training centers.
Simply contact your sales representative or go to Know-How - NETZSCH Analyzing & Testing
