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

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SUMMARY

The discussion centers on the oxidation of tungsten filaments in automotive 12V DC light bulbs during a fire. It establishes that oxidation is a significant factor in filament destruction when the bulb envelope is breached. The minimum oxygen required for oxidation to occur is contingent on the filament's size, with even a single oxygen atom capable of initiating the reaction in a vacuum. The conversation also highlights that the oxidation process is largely irreversible, necessitating only a minimal amount of oxygen to oxidize the filament fully.

PREREQUISITES
  • Understanding of tungsten filament properties
  • Knowledge of oxidation reactions
  • Familiarity with automotive 12V DC lighting systems
  • Basic principles of fire dynamics and oxygen levels
NEXT STEPS
  • Research the chemical properties of tungsten and its oxidation process
  • Study the effects of low oxygen environments on combustion
  • Examine the design and failure modes of automotive light bulbs
  • Learn about fire behavior and flashover conditions in confined spaces
USEFUL FOR

Engineers, fire safety professionals, and anyone involved in the design or analysis of lighting systems and fire dynamics will benefit from this discussion.

j.mcdowell@mcdo
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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
 
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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.
 

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