Davy's Safety Lamp: How Does it Get Oxygen to Burn in Coal Mines?

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Discussion Overview

The discussion revolves around the operation of Davy's Safety Lamp in coal mines, specifically focusing on how the lamp obtains oxygen for combustion while preventing the ignition of methane gas (firedamp). The inquiry explores the mechanisms that allow for safe combustion in an environment where explosive gases may be present.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions how the lamp gets oxygen for combustion, noting the need for an air inlet and expressing confusion about the potential for methane ignition.
  • Another participant clarifies that the mine is open to the outside, implying that miners have access to breathable air.
  • A later reply explains that the wire mesh acts as a flame arrestor, allowing air and firedamp to pass through while preventing flames from propagating outside the mesh.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the complete understanding of the lamp's operation, as some questions remain about the dynamics of air flow and combustion safety in the presence of methane.

Contextual Notes

There are unresolved assumptions regarding the specific airflow dynamics and the interaction between the lamp's design and the presence of methane in the mine atmosphere.

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Hi there!
(It's not actually a homework question)
I just wanted to ask where does the lamp get oxygen to burn on in coal mines.
So there must be an inlet for air. Of course it is explained in my book that as the wire mesh distributes the heat therefore the temperature does not rise to the ignition point of the methane in coal mines.
What i don't get is ,there must be a source of air for the lamp(cuz you don't carry an oxygen cylinder for it).And it must reach the flame and if it contains methane it would burst right away(??)
I just can't get a completed picture of it.I know there must be some reason because it's practically possible.
 
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The mine is open to the outside world. Remember that the miners need air to breath.
 
1/2" said:
Hi there!
(It's not actually a homework question)
I just wanted to ask where does the lamp get oxygen to burn on in coal mines.
So there must be an inlet for air. Of course it is explained in my book that as the wire mesh distributes the heat therefore the temperature does not rise to the ignition point of the methane in coal mines.
What i don't get is ,there must be a source of air for the lamp(cuz you don't carry an oxygen cylinder for it).And it must reach the flame and if it contains methane it would burst right away(??)
I just can't get a completed picture of it.I know there must be some reason because it's practically possible.


The screen acts as a flame arrestor; air (and any firedamp present) can pass through the mesh freely enough to support combustion, but the holes are too fine to allow a flame to propagate through them and ignite any firedamp outside the mesh.

http://en.wikipedia.org/wiki/Davy_lamp
 
Thank you all for your help!
 

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