The limited oxygen index test is a commonly used method for assessing the flammability of materials. Samples of material are exposed to a flame within a chamber. The oxygen content within the controlled environment within the chamber can be varied to within 0.1%. Through an iterative method the maximum percentage of oxygen in the air at which the sample of material extinguishes is determined.
This percentage of oxygen can be used as an indication of how easily a material burns.
The higher the Limited Oxygen Index % value the less flammable a material is.