Incandescent light bulb Small variations in resistivity along the filament cause "hot spots" to form at points of higher resistivity; a variation of diameter of only 1% will cause a 25% reduction in service life. These hot spots evaporate faster than the rest of the filament, which increases the resistance at that point—this creates a positive feedback that ends in the familiar tiny gap in an otherwise healthy-looking filament. Irving Langmuir found that an inert gas, instead of vacuum, would retard evaporation. General service incandescent light bulbs over about 25 watts in rating are now filled with a mixture of mostly argon and
Inert gas In such plants and in oil refineries, transfer lines and vessels can be purged with inert gas as a fire and explosion prevention measure. At the bench scale, chemists perform experiments on air-sensitive compounds using air-free techniques developed to handle them under inert gas. Inert gas is produced on board crude oil carriers (above 8,000 tonnes)(from Jan 1, 2016) by using either a flue gas system or by burning kerosene in a dedicated inert gas generator. The inert gas system is used to prevent the atmosphere in cargo tanks or bunkers from coming into the explosive range. IG keeps the