ASTM C 518 : 1998

1.1 This test method covers the measurement of steady state thermal transmission through flat slab specimens using a heat flow meter apparatus.

1.2 This is a comparative (or secondary) method of measurement since specimens of known thermal transmission properties must be used to calibrate the apparatus. Properties of the calibration specimens must be traceable to an absolute measurement method, and should be obtained from or traceable to a recognized national standards laboratory.

1.3 The test method is applicable to the measurement of thermal transmission through a wide range of specimen properties and environmental conditions. The method has been used at ambient conditions of 10 to 40°C with thicknesses up to approximately 250 mm, and with plate temperatures from -195°C to 540°C at 25 mm thickness (Refs. (5, 6)).

1.4 This test method may be used to characterize material properties which may or may not be representative of actual conditions of use. Other test methods such as Test Methods C236 or C976 should be used if needed.

1.5 To meet the requirements of this test method the thermal resistance of the sample must be greater than 0.10 K[dot]m /W in all directions.

1.6 It is not practical in a test method of this type to try to establish details of construction and procedures to cover all contingencies that might offer difficulties to a person without pertinent technical knowledge. Thus users of this test method shall have sufficient knowledge to satisfactorily fulfill their needs. For example, knowledge of heat transfer principles, low level electrical measurements, and general test procedures is required.

1.7 Standardization of this test method is not intended to restrict in any way the future development of improved or new methods or procedures by research workers.

1.8 Since the design of a heat meter apparatus is not a simple matter, a procedure for qualifying an apparatus is given in 7.8.

1.9 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.