GHFM-02 Bewachter Wärmemengenzähler

A portable guarded heat flow meter for testing the thermal resistance and thermal conductivity of solids.

Ideal für metals, polymers and composites
ghfm-02 guarded heat flow meter
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.

Eigenschaften

The Guarded Heat Flow Meter (GHFM-02) follows ASTM E1530-19 for testing thermal resistance and thermal conductivity of solids, such as metals, polymers and composites. The easy to operate 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 testing of a wide range of materials with low to medium thermal conductivity.

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

The testing stack is made up of a heater – upper plate, with integrated temperature sensor and heat sink – lower plate with integrated temperature sensor on each side of the sample. Additional temperature sensors are placed near the top and bottom surface of the sample.

guarded heat flow meter testing stack

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:

GHFM-The-Fourier-Law

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.

Specification

Materialien

Metalle, Polymere und Verbundwerkstoffe

Messfähigkeiten

Durchgehende Dicke

Wärmewiderstand

0,00007 bis 0,25 m² K/W

Wärmeleitfähigkeit

0,1 bis 15 W/mK

Messzeit

In der Regel 30-60 Minuten

Reproduzierbarkeit

2%

Genauigkeit

5%

Temperaturbereich

20°C – 30°C

Durchmesser der Probe

50,8 mm / 2 in.

Maximale Schichtdicke

25,4 mm / 1 in.

Normen

ASTM E1530-19

Testing Stack & Calibration

standard 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

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.

Calibration Thermal Resistance Graph

Measurement Process

Sample Polymers

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 min.

GHFM sample 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 mins.

GHFM 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 mins.

GHFM Result Calculations

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 mins.

Guarded Heat Flow Meter (GHFM) Models Comparison


ghfm-01

Modelle

GHFM-01

GHFM-02

Materialien

Metals, Polymers, Composites, and Pastes

Metalle, Polymere und Verbundwerkstoffe

Messfähigkeiten

Durchgehende Dicke

Durchgehende Dicke

Applications

General Testing

General Testing

Wärmeleitfähigkeit

0.1 to 100 W/m•K*

0.1 to 15 W/m•K

Durchmesser der Probe

50 to 50.8 mm

50,8 mm / 2 in.

Sample Thickness

Up to 25 mm | Thin-films down to 0.01 mm with optional Software

25,4 mm / 1 in.

Maximale Schichtdicke

25,4 mm / 1 in.

25,4 mm / 1 in.

Temperaturbereich

-20 to 310 °C**

20 to 30 °C

Druck

Automated up to 379 kPa (55 psi)

Manuell

Messzeit

30 to 45 minutes

30 to 45 minutes

Genauigkeit

± 3 %

5 %

Reproduzierbarkeit

± 1 to 2 %

2 %

Normen

ASTM E1530-19

ASTM E1530-19

*Above 60 W/m·K, the material should be a minimum of 12.5 mm thick
**Chilled circulator included with each system

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