Flammable vapor is considered to have a dangerous concentration when it exceeds what percentage of its flammable limit?

Flammable vapor is deemed to have a dangerous concentration when it exceeds 25% of its lower flammable limit (LFL). At this level, the concentration of flammable vapor in the air becomes significantly high enough to pose a risk of ignition, creating a fire hazard. Knowing the LFL is crucial for preventing accidents and ensuring safety in environments where such vapors are present.

In general, the LFL is the lowest concentration of a vapor in air that can ignite if an ignition source is present. Concentrations above this threshold can lead to explosive mixtures. Therefore, when the concentration reaches 25% or more of the LFL, there is a substantial risk, and safety protocols must be intensified to prevent potential ignition and increase safety measures accordingly. This information serves as a foundational guideline for those working in HVAC systems, refrigeration, and other fields involving flammable materials.