主要特點(diǎn)：

The flame persistency test according to NF P 92-504 is a reaction to fire complementary test for M classification of building and fitting materials. It is used for flexible and rigid materials of any thickness which develop holes without inflammation or with short time inflammation during the main test （electrical burner test according to NF P 92-503 or radiation test in an epiradiator cabinet according to NF P 92-501）. In that case, the flame persistency test becomes the deciding test for M classification of materials.
In principle, if there is no flame persistency after burner withdrawing, the material can be M1 classified. In case of flame persistency after burner withdrawing, the M2 or M3 classification will be made depending on whether the duration of inflammation is = 5 s or > 5 s. In case of inflamed or not dripping, the dripping test （NF P 92-505） is carried out.