Thermal Insulation |
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INSULATION TESTING |
Insulation
Testing For those interested in obtaining greater detail on individual test specifications, they can be ordered directly from ASTM at http//www.astm.org. Bogus Tests or
Advertising Hype? Further complicating the issue is the growing frequency with which manufacturers intentionally use improper (although otherwise legitimate) test methods to gain an artificially high performance rating (i.e. "R" value). While such tactics greatly overrate the performance of the product in its intended (and most common) applications, the practice remains entirely legal since the manufacturer can provide calibrated test data to document their claims. Perhaps the clearest example of this is the addition of an aluminum (or similar) "radiant heat barrier" foil to the surface of an insulation material. As explained in the section on radiant heat (see Heat Movement - Conduction, Convection and Radiation), this increasingly common and widely misunderstood practice permits the manufacturer to legitimately "document" virtually any "R" value desired by simply varying the ratio of radiant to conductive heat used in the test. While the test data is real enough, the problem occurs when the product is advertised for use in applications which bear little resemblance to the test conditions. They fail to point out that in most applications, where the foil facing is pressed against another material, no benefit is gained by using such foils. Poor Enforcement Responsibility for the enforcement of the insulation standard test laws lies with the U.S. Federal Trade Commission. To date, there has never been a federal action taken by the FTC against an insulation manufacturer for providing misleading "R" values. As a result, many don't bother to test their material at all preferring instead to simply make a "guesstimate" which, as you might imagine, may be more than a little optimistic. Politically inclined individuals might want to add their voice to those of us who would like to see better enforcement by contacting the Federal Trade Commission directly at http://www.ftc.gov/. As engineers working with
thermal insulations as well as heating and cooling system designs, it is
imperative that the Engineers using the information contained in this table are reminded that the ASTM C-518 test method and the temperatures used in this testing are applicable for general use in refrigerating, freezing and air conditioning applications in which conduction is the primary means of heat movement. This may, or may not be indicative of the conditions in your application.
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