What term describes the concentration of a flammable gas or vapor in air that can ignite?

The term that accurately describes the concentration of a flammable gas or vapor in air that can ignite is the "flammable range." This range defines the limits of concentration from the lower explosive limit to the upper explosive limit, within which a gas or vapor can ignite if an ignition source is present.

The lower explosive limit (LEL) refers specifically to the minimum concentration of a gas or vapor needed to form an ignitable mixture in the air, while the upper explosive limit (UEL) indicates the maximum concentration. Ignition point usually refers to the temperature at which a substance will ignite without any additional energy source. Therefore, while the lower and upper explosive limits are critical components of the flammable range, they do not encompass the entire concept, which involves both limits together. Thus, "flammable range" represents the full spectrum of potential ignitability.