<p>This International Standard specifies two laboratory test methods, based on slicing and scaling techniques, to</p>
<p>determine the long-term changes in the thermal resistance of closed-cell (normally 90 %) cellular plastic materials</p>
<p>that contain gases which, through diffusion processes, affect the properties of a foam with time.</p>
<p>Using standard methods for the measurement of thermal resistance, method A consists of periodic measurements</p>
<p>performed over a short time interval on thin specimens conditioned in a controlled ambient temperature</p>
<p>environment. The results of relative change with time are used in conjunction with a mathematical technique to</p>
<p>derive the thermal resistance of greater thicknesses of the material as a function of time.</p>
<p>Method B describes a simple test to determine a conservative design life-time value (25 years and longer) for an</p>
<p>unfaced, closed-cell, cellular plastic product. This method is limited currently to unfaced homogeneous materials.</p>
<p>For this method, multiple specimens of the core and surfaces of materials with variations in the slope of the primary</p>
<p>stage thermal resistivity and a time relationship of less than 10 % within a sample are considered to be</p>
<p>homogeneous. Generally, products with natural skins or with density deviations normally found with such products</p>
<p>may be considered acceptable for test by this technique.</p>
Registration number (WIID)
2488
Scope
<p>This International Standard specifies two laboratory test methods, based on slicing and scaling techniques, to</p>
<p>determine the long-term changes in the thermal resistance of closed-cell (normally 90 %) cellular plastic materials</p>
<p>that contain gases which, through diffusion processes, affect the properties of a foam with time.</p>
<p>Using standard methods for the measurement of thermal resistance, method A consists of periodic measurements</p>
<p>performed over a short time interval on thin specimens conditioned in a controlled ambient temperature</p>
<p>environment. The results of relative change with time are used in conjunction with a mathematical technique to</p>
<p>derive the thermal resistance of greater thicknesses of the material as a function of time.</p>
<p>Method B describes a simple test to determine a conservative design life-time value (25 years and longer) for an</p>
<p>unfaced, closed-cell, cellular plastic product. This method is limited currently to unfaced homogeneous materials.</p>
<p>For this method, multiple specimens of the core and surfaces of materials with variations in the slope of the primary</p>
<p>stage thermal resistivity and a time relationship of less than 10 % within a sample are considered to be</p>
<p>homogeneous. Generally, products with natural skins or with density deviations normally found with such products</p>
<p>may be considered acceptable for test by this technique.</p>
