How Much Oxygen Is Needed for Light Bulb Filament Oxidation in a Fire?

[j.mcdowell@mcdo]

Since oxidation is the reason for light bulb tungsten filament destruction in case of breach of the bulb envelope, while illuminated, what is the minimum oxygen required for oxidation to occur. Assume an automotive 12vdc bulb which has a greater diameter filament. However if it is considered that this is in the course of a fire and near flashover where the oxygen content may be less than 10% is this a factor?

Thank you

 

[mgb_phys]

I'm not sure oxidation is the main cause of filament failure so much as the material evaporating.
In a vacuum there would be no minimum level of oxygen required for oxidation to coccur - since a single oxygen atom would presambaly sooner or later touch the filament and react. The minimum needed to oxidise the full thickness of the the filament would depend on the size. Again since the oxidation reaction is pretty much one way you would only need this minimum amopunt of oxygen.