“Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus”.

The ASTM C-518 test method covers the measurement of steady state thermal transmission through flat slab specimens using a heat flow meter apparatus. The heat flow meter has the following advantages:

* Simple concept
* Rapid
* Applicable to a wide range of test specimens

The heat flow meter apparatus establishes a steady state, linear heat flow through the insulation via two parallel plates which are kept at constant, but different temperatures.

The apparatus requires calibration, which is carried out using materials that are expected to exhibit similar thermal characteristics as the test specimen, creating additional uncertainty in the test results. As such, this test method is considered a secondary method of measurement.

For a more detailed description of the test scope, visit the ASTM web site at: www.astm.org/Standards/C518.htm