Welding & Blue Light: Is Nitrogen the Cause?

In summary, welding emits blue light because it uses a high amount of energy, resulting in a high frequency of light being scattered/emitted. Blue light has a higher frequency than other colors, and this is due to the ionization of O2 molecules in the air during welding, which emit a blue color. The type of welding, such as MIG with Argon gas, can also affect the color of the light emitted.
  • #1
cragar
2,552
3
when someone welds , why does it emit blue light , is it because of the ntirogen in the air.
 
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  • #2
Welding uses/has a very high amount of energy. From E=hf, high energy implies a high frequency of light scattered/emitted. And blue light has a higher frequency than red, green yellow etc...

That's why yellow/orange flames are less hotter than blue flames.
 
  • #3
alcohol has a blue flame and it burns cooler than gasoline.
 
  • #4
Good question.
It depends on the molar density when comparing alcohol vs gasoline. You would need to use the ideal gas law to work out their temperatures.

My explanation above applies to one particular fuel.
ie. a blue alcohol flame is hotter than a yellow alcohol flame OR a blue gas flame is hotter than a yellow gas flame.
 
  • #5
ok i see
 
  • #6
I'm not a materials engineering, but I believe that in welding (as opposed to complete vs. incomplete combustion, as alluded to by n0_3sc) you have a few different things happening simultaneously. The hot sparks flying off (which radiate black body depending on the temperature of the sparks), and the electric arcing--breaking down (and ionizing) either the air or whatever process gas is being used, and the material in the electrode.

Black body radiation (what happens when you heat something up to a certain temperature):
http://en.wikipedia.org/wiki/Black_body

Electric arc discharge:
http://en.wikipedia.org/wiki/Electric_arc

Flame testing (happens with various metal ions, including trace ones):
http://en.wikipedia.org/wiki/Flame_test

Hope this helps!
 
  • #7
Your question needs to be more specific. What kind of welding are you talking about, MIG, TIG, Arc? Welding usually requires a shielding gas (typically CO2 or Argon) so nitrogen isn't a factor.
 
  • #8
mig , argon
 
  • #9
n0_3sc said:
Welding uses/has a very high amount of energy. From E=hf, high energy implies a high frequency of light scattered/emitted. And blue light has a higher frequency than red, green yellow etc...

I think the reason that arc discharge in air looks blue (just like lightning), is because O2 molecules are easier to ionize (lower ionization energy) and therefore, ionized O2 emits blue color.
Am I right?
 

1. What is blue light and how does it relate to welding?

Blue light is a type of visible light that has a shorter wavelength and higher energy than other colors in the visible spectrum. It is commonly produced by welding processes, as well as other sources such as electronic devices and the sun.

2. Is nitrogen responsible for the blue light produced during welding?

While nitrogen is present in the air and can contribute to the blue light produced during welding, it is not the sole cause. Other factors such as high temperatures and the presence of other gases also play a role in the blue light emission.

3. Is blue light from welding harmful to human health?

Yes, exposure to high levels of blue light can have negative effects on human health, including eye damage and disruption of sleep patterns. It is important for welders to take proper safety precautions, such as wearing protective eyewear, to minimize their exposure to blue light.

4. Can the use of nitrogen gas in welding reduce the amount of blue light produced?

Yes, using nitrogen gas instead of air in welding processes can reduce the amount of blue light emitted. This is because nitrogen gas is inert and does not react with the high temperatures and other factors that contribute to blue light production. However, it is important to note that other safety measures should still be taken to protect against blue light exposure.

5. Are there any alternatives to using nitrogen gas to reduce blue light from welding?

Yes, there are other methods that can be used to reduce the amount of blue light produced during welding. These include using filters or lenses that block out blue light, as well as adjusting the welding process to minimize the overall emission of blue light.

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