After the ignition source is removed, what class of material will not propagate a flame beyond safe limits?

The class of materials described as Flame Resistant is designed specifically to prevent or resist the spread of flames beyond a certain limit. These materials work by slowing down the combustion process, either by not easily catching fire or by limiting the intensity and duration of flames. Flame-resistant materials are commonly used in applications where fire safety is a critical concern, such as in aircraft interiors and structural components.

When an ignition source is removed, materials classified as flame resistant will not continue to burn or propagate flames easily, ensuring safety in environments where flammable materials are present. This characteristic makes them essential in preventing potential fire hazards and ensuring compliance with safety regulations.

In contrast, highly flammable materials would ignite quickly and burn aggressively, while combustible materials would burn under the right conditions. Non-combustible materials, while not supporting combustion, do not actively resist ignition in the same manner as flame-resistant materials, which are specifically engineered to control and limit fire propagation. Thus, flame-resistant materials are the most effective in preventing flame spread beyond safe limits when an ignition source is removed.