Heat Flow Meter (HFM-25)

The HFM-25 is a portable heat flow meter for the measurement of thermal resistance and thermal conductivity of small samples of insulation and construction materials.

Best For small samples of insulation and construction materials.

ASTM C518 | ISO 8301

JISA 1412 | EN 12667

Standard Test
Method

20 to 30°C

Temperature
Range

The Heat Flow Meter (HFM) 25 for the measurement of thermal resistance and thermal conductivity of small samples of insulation and construction materials. Offering the testing power of a full-size heat flow meter, optimized for small insulation samples and budget.

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    Features
    HFM-25 Features
    The economic HFM-25 was designed to meet the growing need for steady-state testing of small samples of insulation for true thermal resistance and thermal conductivity.

     

    Designed with simplicity in mind, a sample is positioned between the two heating – cooling plates. Plate contact is controlled manually, with variable pressure applied with the use of standard weights. Thickness is conveniently reported with included digital gauge. Testing on compressible samples is possible with included shims.

    Ambient room temperature is automatically detected, users can choose from 5, 10, 15, and 20 °C delta ranges. One heat flux sensor is integrated into each plate and is used to monitor heat flux (Q/A), generated due to the difference in temperature (DeltaT) between the top and bottom plate at regular intervals until steady-state heat flux is observed. The composite heat flux is then used to measure thermal resistance (R) and calculate thermal conductivity (λ) according to Fourier’s Law.

    • Insulation samples as small as 50 x 50 x 2 mm and thickness up to 25.4 mm
    • Large samples can also be loaded for multiple location testing
    • Follows international standards: *ASTM C518, ISO 8301, JIS A1412, and EN 12667
    Specifications
    Thermal Conductivity 0.01 to 0.3 W/m•K
    Directions Through-Thickness
    Accuracy 3%
    Reproducibility 1%
    Temperature Delta 5°C, 10°C, 15°C and 20°C at ambient temperature
    Type of SensorsFlux Sensors (x2) with surface thermocouples

    Minimum Sample Size 50 x 50 x 2 mm
    Maximum Sample Thickness 25.4 mm
    Maximum Sample (LxW) Unlimited
    Standard *ASTM C518, ISO 8301, JIS A1412, and EN 12667

    * applies for materials below 0.1 W/mK

    Applications
    Location Testing for Homogeneity
    Location Testing for Homogeneity

    The homogeneity of NIST 1450d high-density fibrous glass board was measured with the HFM-25. Designed to test small samples or locations of 25 mm x 25 mm. The open concept sample clamping allows testing of large samples.

    The four corners of the board were measured to analyze the homogeneity of sample. The % RSD from location to location was less than 1%, confirming the homogeneity

    Aerogel Blanket

    Aerogel Blanket

    Aerogel blanket sample (50 x 50 x 9.58 mm) was selected to test by the HFM-25. Thermal conductivity of 0.014 W/m•K was measured at 23°C, which is within 3% of the manufacturer’s specification (measured by GHP – ASTM C177).

    NIST SRM 1450d

    A sample of NIST SRM 1450d was measured for thermal conductivity for accuracy. The certified thermal conductivity for the NIST piece at 25°C is 0.0329 W/m•K. The measured thermal conductivity was 0.0330 W/m•K, which is within 1% of the certified value.

    Heat Flow Meter (HFM) Models Comparison

    Models
    HFM-100
    Materials
    Insulation, Solids, Construction Materials
    Type of Sensors
    Flux Sensors (x2)
    Applications
    General Testing
    Direction
    Through-thickness
    Thermal Conductivity Range
    0.002 to 0.5 W/m•K
    Specific Heat
    Optional
    High Thermal Conductivity Kit
    Up to 2.5 W/m•K
    Measurement Time
    30 to 40 minutes
    Reproducibility
    ± 0.5 to 1%
    Accuracy
    ± 1 to 2%*
    Plate Temperature Range
    -20 to 70 °C
    Smallest Sample Size
    250 x 250 x 5
    Maximum Sample Size
    300 x 300 x 100
    Standards
    ASTM C518, C1784, ISO 8301, JIS A1412, EN 12667, and EN 12664

    Models
    HFM-50
    Materials
    Insulation, Solids, Construction Materials
    Type of Sensors
    Flux Sensors (x2)
    Applications
    General Testing
    Direction
    Through-thickness
    Thermal Conductivity Range
    0.002 to 0.5 W/m•K
    Specific Heat
    Optional
    High Thermal Conductivity Kit
    Up to 2.5 W/m•K
    Measurement Time
    30 to 40 minutes
    Reproducibility
    ± 0.5 to 1%
    Accuracy
    ± 1 to 2%*
    Plate Temperature Range
    -20 to 70 °C
    Smallest Sample Size
    150 x 150 x 5
    Maximum Sample Size
    200 x 200 x 50
    Standards
    ASTM C518, C1784, ISO 8301, JIS A1412, EN 12667, and EN 12664

    Models
    HFM-25
    Materials
    Insulation,Textiles
    Type of Sensors
    Flux Sensors (x2)
    Applications
    Small Insulation
    Direction
    Through-thickness
    Thermal Conductivity Range
    0.01 to 0.3 W/m•K
    Specific Heat
    N/A
    High Thermal Conductivity Kit
    N/A
    Measurement Time
    20 minutes
    Reproducibility
    1%
    Accuracy
    3%
    Plate Temperature Range
    10 to 40°C
    Smallest Sample Size
    50 x 50 x 2
    Maximum Sample Size
    300 x 300 x 25
    Standards
    ASTM C518, C1784, ISO 8301, JIS A1412, EN 12667, and EN 12664
    *Performance verified with NIST 1450d / 1450e | Chilled circulator required

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