What is the term for gas that can be ignited at certain concentrations in the air?

The term for gas that can be ignited at certain concentrations in the air is flammable gas. Flammable gases have lower and upper flammability limits, which are the minimum and maximum concentrations of the gas in the air that will support combustion. When the concentration of a flammable gas falls within this range and an ignition source is present, the gas will ignite and potentially lead to a fire or explosion.

Inert gases, on the other hand, do not support combustion due to their chemical stability and lack of reactivity. Toxic gases are harmful to health when inhaled or absorbed, but their ability to ignite does not define their primary hazard. Non-flammable gases are those that do not ignite under normal conditions, making them inherently safe from combustion. Understanding these distinctions is crucial for safety protocols in handling and storing gases, particularly in environments where flammable substances are used.