BS476 Part 7 Surface spread of flame火焰蔓延等级测试：是用于测试样品表面火焰延伸，并根据延伸速度及延伸长度确定燃烧等级。BS476第7部分将产品火焰蔓延等级划分为四个等级：BS476-7 Class 1，BS476-7 Class 2，BS476-7 Class 3，BS476 Class 4这个四个等级。
BS476-7: Fire tests on building materials and structures-Part 7 method of test to determine the classification of the surface spread of flame of products.
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