Guarded Heat Flow Meter (GHFM-02)

The GHFM-02 follows the trusted steady-state approach with the addition of a guard to limit the effects of lateral heat loss. This design allows the testing of a wide range of materials with low to medium thermal conductivity. Measures thermal conductivity and thermal resistance.

Best For Metals, Polymers, and Composites

ASTM E1530-19

Standard Test
Method

20°C to 30°C

Temperature
Range

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The sample is subjected to a steady-state through-thickness temperature gradient and the thermal conductivity is obtained by measuring the temperature difference across it and one additional reference temperature.

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    Theory and Features
    GHFM-02 Heater Testing Stack
    The testing stack is made up of a heater composed of an upper plate with an integrated temperature sensor, and heat sink where the lower plate has an integrated temperature sensor on each side of the sample. Additional temperature sensors are placed near the top and bottom surface of the sample.

    Once steady-state temperature across the sample is achieved, the Fourier law equation can be applied. It can readily be shown that for any solid sample, the ratio RS (m2 K/W), equal to the thickness of the sample, d (m), to its thermal conductivity, λ (W/mK), can be obtained from the temperatures measured:

    Thermal Resistance Guarded Heat Flow Meter Equation

    The above equation is linear in form and is the working equation of the instrument. Constants F (m2 K/W) and Rint (m2 K/W), can be obtained by calibration of the instrument. To this effect, calibration samples of known thermal conductivity and hence, thermal resistance is employed. Calibrated results for thermal resistance and thermal conductivity are reported.

    • Follows international standard ASTM E1530-19
    • Economical and Accurate
    • Easy to use
    • Variable Thickness
    Specification
    Materials Metals, Polymers and Composites
    Measurement Capabilities Through-Thickness
    Thermal Resistance 0.00007 to 0.25 m2 K/W
    Thermal Conductivity 0.1 to 15 W/mK
    Measurement Time Typically 30-60 minutes
    Reproducibility 2%
    Accuracy 5%
    Temperature 20°C – 30°C
    Sample Diameter 50.8 mm / 2 in.
    Maximum Thickness 25.4 mm / 1 in.
    Standards ASTM E1530-19
    Testing Stack & Calibration
    Standard GHFM-02 Testing Stack
    Standard GHFM-02 Testing Stack

    The GHFM-02 comes with a standard 50.8 mm (2 inches) diameter sample opening to allow testing of metals, polymers and composite materials. Sample thickness can vary up to 25.4 mm (1 inch). Typically a 20°C temperature delta from top to bottom of the sample is set to a mean temperature of 20°C to 30°C. Temperature points TU , TL and TH are then entered into the included GHFM software for auto calculation of thermal resistance and calibrated thermal conductivity results.

    Calibration
    Calibration

    The basic GHFM-02 comes calibrated to calculate thermal conductivity from thermal resistance range of 0.0032 to 0.1270 m2 K/W. Additional available calibration ranges allow testing from 0.00007 to 0.25 m2 K/W.

    Sample Measurements
    polymer sample
    The Sample

    GHFM-02 samples should be 50.8 mm or 2 inches in diameter. The top and bottom surfaces should be flat and parallel.

    Approximate Time: < 1 minute

    GHFM-02 Testing Stack
    Place Sample on GHFM-02 Testing Stack

    A thin layer of the included contact paste should be added to the top and bottom of the sample surface.

    Approximate Time: < 2 minutes

    the measurement
    Measurement

    For a sample mean temperature of 25°C, the top heater should be set to 35°C, while the bottom heat sink chiller – circulator set to 15°C to achieve a delta temperature of 20°C.

    Approximate Time: < 2 minutes

    Exporting Results
    Result Calculations

    Once stable, temperatures from upper temperature (TU), lower temperature (TL), and heat sink temperature (TH) are then entered into the GHFM-02 software for auto calculation of thermal resistance, and calibrated thermal conductivity results.

    Approximate Time: < 60 minutes

    Related Research Papers
    Find related research papers:

    Thermal Conductivity and Contact Resistance Measurements for Adhesives

    Thermal adhesives that contain large proportions of high thermal conductivity filler materials are extremely useful in electronics and manufacturing. Due to the importance of these fillers it is crucial to…

    Measurements of the Thermal Conductivity of Lithium Polymer Battery Composite Cathodes

    Thermal management is extremely important for large size batteries, however, inaccurate values have been used in the past for modeling. This paper investigates the thermal conductivity of the composite cathodes.

    Applications
    Thermal Conductivity of Solvents
    3D Printed Materials

    Measuring the thermal conductivity of 3D printed filament materials

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