The limiting oxygen index (LOI) is the littlest oxygen concentration needed to let the ignition continue with a combination of oxygen (O₂) and nitrogen (N₂) gases at room temperature. Strategies for estimating the oxygen index are widespread and have numerous applications, beginning with innovative work testing, which characterizes the conduct of materials during burning, up to quality control of fabricated items. The fire tests depend on basic tests such as cone calorimetry (CC), LOI, and single burning item (SBI).
The LOI device classifies the materials into flammable and non-flammable. Many standards can be applied to oxygen index devices, but ISO 4589 is the most standard used in fire testing. The uncertainty was determined during the tests, which included quantitative and qualitative measurements. This manuscript was concerned with evaluating the contributions of available sources of errors included in the uncertainty budget and applying the risk analysis concepts to mitigate its effect on the expanded final uncertainties associated with the final results.