Flammable event with different time duration

What if a flammable event has a different time duration than the 5 kw/m2 for 40 seconds?

EPA recognizes that flammable events may occur for a different amount of exposure time. Therefore, the owner or operator should determine the distance to an equivalent exposure - e.g. if the flammable event occurs for 20 seconds, determine the distance to an equivalent exposure level.