This standard specifies the determination of visible light transmission for transparent materials by using a photometer employing a defined light source and a photocell matched to the response of the human eye.
Because the materials under test are basically colourless, certain deviations from ideal conditions, indicated in the test, are allowable.
Regulation (eu) No 305/2011 of the European Parliament and of the Council of 9 march 2011 laying down harmonised conditions for the marketing of construction products and repealing council directive 89/106/eec
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