The Heat Flow Meter (HFM-25) for testing thermal resistance and thermal conductivity of insulation and construction materials. Offering the testing power of a full-size heat flow meter, optimized for small insulation samples and budget. The HFM-25 is controlled by the included HFM Software, offering automation of calibration, testing and results summary functions.

Thermtest 25 Series Heat Flow Meter

Picture 1. Thermtest 25 Series Heat Flow Meter.

Following international standards, the HFM-25 is designed for testing both homogenous and heterogenous materials and complies with ASTM C518. The HFM-25 allows for smaller sample sizes which are representative of materials typically found in insulation and construction industries.

Sample Configuration

For small samples (min 50 x 50 mm), samples can easily be arranged for simple testing.

Picture 2. 50 x 50 mm piece of NIST 1450D

For larger samples (no maximum), samples can conveniently measured at a specific location.

300 x 300 mm piece of NIST 1450D

Picture 3. 300 x 300 mm piece of NIST 1450D

Measurement of American Aerogel Blanket

In this experiment, the thermal conductivity of Spaceloft Subsea Aerogel insulation of 9.58 mm thick from Aspen Aerogels was measured with the Thermtest HFM-25. Aerogel is a lightweight solid derived from gel in which the liquid component has been replaced with air. This process creates a solid material with two interesting properties: an extremely low density and extremely low thermal conductivity of this solid. The temperature of the upper plate was 35°C and the lower plate was 15°C, obtaining an optimal temperature delta of 20 degrees.

Aerogel sample outside and in between plates of the HFM-25

Picture 4. Aerogel sample outside and in between plates of the HFM-25. Sample Sze of 50 mm square and 9.58 mm thick

Table 1: Results of the average thermal conductivity and thermal resistance of Subsea Spaceloft Aerogel sample.

Measured Thermal Conductivity (W/m·K) Expected Thermal Conductivity (W/m·K)
0.0140 0.0140

Reference: Reference: – Measured via ASTM C177. Sample measured by Thermtest using ASTM C518.