BS476-7火焰蔓延等级关系到火灾是否波及到邻近可燃物，或者加速邻近可燃物而使火势扩大。BS476-7火焰蔓延等级为四个等级分别为：BS476-7 Class 1；BS476-7 Class 2；BS476-7 Class 3；BS476-7 Class 4，这四个等级。BS476-7等级1的危险波及性最小，BS476-7等级2的危险还在可控范围内。
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.
...
