HFM-100 HEAT FLOW METER

FEATURED CAPABILITIES

• Two flux sensors for accurate measurement of thermal conductivity
• Peltier heating / cooling plates for rapid control of temperature
• Thickness is measured to an accuracy of 0.1 mm (0.004 in) with the use of four digital optical encoders
• Front panel operation allows full control of all HFM functions, or use the intuitive HFM Software for basic and additional functions, such as printing and exporting
• Plate clamping can be automated or set to a user defined thickness — ideal for compressible materials
• Follows international standards: ASTM C518, ISO 8301, and EN 12667

Thermtest’s cost effective Heat Flow Meter is the perfect choice for steady-state measurements of thermal resistance and thermal conductivity of insulation products and construction materials. Thermtest’s HFM 100 Heat Flow Meter instrument has been rigorously designed to meet the requirements of international standards including ASTM C518, ISO 8301, and EN 12667.

Operating the HFM is simple – a sample is placed between two heating – cooling plates, and the upper plate, powered by stepper motors positioned in each corner, lowers to contact the top of the sample. Plate contact with the test sample is controlled by a standard pressure applied, or by entering a user defined sample thickness. Sample thickness (L) is measured to the nearest 0.1 mm (0.004 in) by individual optical encoders that control the stepper motors. Integrated logic between stepper motors allows the upper plate to sense and adjust for samples with surface variations, optimizing the contact between plate and test sample during measurements.

A heat flux sensor is integrated into each plate and used to monitor heat flux (Q/A), generated by the difference in temperature (ΔT) between the top and bottom plate at regular intervals, until steady-state heat flux is observed. The composite heat flux is then used to calculate thermal conductivity (λ) and thermal resistance (R) according to Fourier’s Law.

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 (ΔT) between the top and bottom plate at regular intervals, until steady-state heat flux is observed. The composite heat flux is then used to calculate thermal conductivity (λ) and thermal resistance (R) according to Fourier’s Law.
 

HFM 100 SPECIFICATIONS

Following international standards, the HFM 100 Heat Flow Meter Method is designed for testing both homogeneous and heterogeneous materials.
The HFM 100 sample size allows for representative testing of materials typically found in insulation and construction industries.

Method is continually improved; specifications are subject to change without prior notice.
*Performance verified with NIST 1435d / 1450e | †Chilled circulator required


ACCURACY & REPEATABILITY OF THE HEAT FLOW METER METHOD

A sample of NIST SRM 1450d was repeatedly tested to confirm the accuracy and repeatability of the heat flow meter method. Prior to each of 20 measurements, the NIST 1450d sample was removed, and then placed back within the HFM-100 chamber. The certified thermal conductivity for the NIST piece at 20˚C (68˚F) is 0.03239 W/mK (0.2246 BTU/(hr·ft·°F)). The average thermal conductivity value received from all 20 tests was 0.0325 W/mK (0.2253 BTU/(hr·ft·°F)). All tests had a repeatability within 0.5%, and an accuracy within 1% of the certified value.

HIGH THERMAL CONDUCTIVITY KIT

With the added High Thermal Conductivity Kit, the HFM-100 is able to accurately, and efficiently measure higher thermal conductivity materials, such as glass and ceramics. For such applications, an external thermocouple kit is used in combination with the sample being tested. Macor, Quartz, and Pyrex were tested in the HFM from 10˚C to 60˚C (50˚F to 140˚F). All measured values are within the stated accuracy of the system, +/- 5%.