What is spread of flame test?

Flame spread tests aim at measuring the tendency of a flame to propagate over a substrate and directly correlate to surface flame propagation in a real fire scenario.

The standard is BS 476-7. The test method is used to determine the lateral extension of the sample surface and based on the speed. And the extension length determines the burning level. BS 476-7 is primarily used to measure the flame extension of exposed surfaces on walls and ceilings.
The test method is to measure the critical radiant flux by igniting the sample with a small flame by withstanding the gradual change of radiant heat energy. The heat radiant panel measures 850mm X 850mm. The test specimen holder is water cooled and equipped with a perforated calibration plate and a thermal radiant flux sensor to calibrate the thermal radiance flux curve. The test instrument has high requirements on the laboratory site, and the user needs more safety measures before the test instrument can be assembled.