Bullet igniting dynamite?

Discussion in 'General Science & Technology' started by Dinosaur, Jul 12, 2015.

  1. Dinosaur Rational Skeptic Valued Senior Member

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    In some western action TV/Movie dramas, a box of dynamite is exploded by a rifle bullet. I do not think this would happen.

    A container of nitro-glycerin is likely to explode due to an impact. Nitrogen chloride is extremely volatile & explodes due to impact or even strong sunlight.

    Dynamite is a mixture of nitro-glycerin invented to provide a safe explosive requiring a detonator.
     
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  3. sideshowbob Sorry, wrong number. Valued Senior Member

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    For a start, what do you think a "detonator" is?

    I would suggest that it's a means of transferring energy to the dynamite - enough energy to activate the explosion.
     
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  5. cosmictraveler Be kind to yourself always. Valued Senior Member

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    Many times fuses are inside the box which the dynamite is kept. So if the bullet were to strike that fuse it could lead to an explosion.
     
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  7. Kristoffer Giant Hyrax Valued Senior Member

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    I'm pretty sure detonators and explosives are usually kept separate. This was in regards to a western however... So sure.
     
  8. Stryder Keeper of "good" ideas. Valued Senior Member

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    I did a quick scan of wiki for my thoughts, I know that Dynamite "sweats" over time and I wondered if that would make it more dangerous, the answer is yes:

    So basically if the dynamite hasn't been stored correctly and turned?, it could well become more prone to explosions from shock or friction.
     
    KitemanSA likes this.
  9. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    Nobel's innovation was to store the nitrogen-ized glycerin in the cavities of diatoms (singled-celled glass-walled plants). This worked at stabilizing it from explosion from slight impact. A much stronger impact is required, usually from a small detonated explosion. https://en.wikipedia.org/wiki/Dynamite

    Sweating over time makes 'safe' dynamite very unsafe.
     
  10. Dinosaur Rational Skeptic Valued Senior Member

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    So far, no Post has answered my Question.

    I do not think dynamite would normally explode due to firing a bullet into a box of dynamite.

    Walter L. Wagner Post # 6 is probably correct for other than a box of newly made dynamite.

    Note Post #5 by Stryder, which indicates that modern dynamite is safer than that from the Old West.

    It seems to me that the TV & Hollywood movies are not accurate relating to igniting dynamite by a bullet into a box of it, excepting dynamite stored for too long.
     
  11. Kristoffer Giant Hyrax Valued Senior Member

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  12. sideshowbob Sorry, wrong number. Valued Senior Member

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    You didn't answer my question: What do you think a detonator does?
    How is being struck by a bullet different from a detonator?
     
  13. timojin Valued Senior Member

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    For safety nitroglycerin perhaps is mixed with methanol as the alcohol evaporate then the nitroglycerine will explode due to shock ?
     
  14. Kristoffer Giant Hyrax Valued Senior Member

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    A detonator starts an explosive reaction by a quick transfer of energy.

    As per the video I linked above it seems like that energy transfer is plausible.
     
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  15. Dinosaur Rational Skeptic Valued Senior Member

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    From SideShowBob Post #9
    It depends on the substance.

    Gun cotton (Nitro-Cellulose) cannot be exploded by firing a bullet into it. It requires some type of detonator. Electricity or mercury fulminate. I do not remember the details. Further more, igniting gun cotton will merely cause it to burn rapidly. If not enclosed (Example: In an artillery shell), all you get is a fire.

    When I was a teenager (1942-1949), it was possible to buy all sorts of substances which are controlled today. I made gun cotton as well as black gun powder, & could have made nitrogen chloride.

    Gun cotton is not dangerous unless you are stupid. Nitrogen Chloride scared me & I did not try to make any.

    A high school buddy of mine killed himself trying to make a pipe bomb. He used a metal rod to tamp black gunpowder into a piece of pipe. A spark ignited the gun powder & the metal rod got him in the stomach.


    I do not think that firing a bullet into a box of newly manufactured dynamite will explode it. Dynamite was invented by Noble to allow it to be used safely & not detonate due to impact. I am pretty sure you could drop a box of new dynamite from 25-50 feet in the air & not explode it. I would not bet big money on this since I never tried it.

    I think it is still possible to buy the ingredients for black gun powder, but am not sure about this. It requires Potassium (sodium?) nitrate, charcoal, & sulfur. Making gun cotton requires the use of concentrated acids, which might be controlled substances today.

    BTW: 1942-1949 was a different era. I used to carry a Bowie Knife with a 12 inch blade to school. Nowadays, they would call the police. Several of us played a game with knives call Mumbley-Peg, whittled, & threw them at trees or other wooden targets.
     
  16. sideshowbob Sorry, wrong number. Valued Senior Member

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    Still no answer to my question.

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    What's the difference between the bullet impact and the mercury fulminate explosion? Is there a vast difference in the amount of energy transferred?

    It was before 9-11. I knew guys who experimented with black powder in the 80s anyway.
     
  17. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    Hollywood & TV are RARELY accurate with regard to the "explodability" of ANYTHING.
    Bullets will not (absent exceptional circumstances) cause a car's fuel tank to explode.
    A car impacting the bottom of a quarry will not (absent careful rigging for just such an effect) explode.
    Hell, only yesterday I watched a TV programme where a guy "ran over" a Thai wooden boat carrying fruit with a jet ski. The FRUIT and wooden boat exploded!
    Maybe bananas and the like should be controlled substances.


    sideshowbob: Is there a vast difference in the amount of energy transferred?
    Yup. A HUGE difference.
    A bullet doesn't (normally) transfer all of its energy anyway, but (lacking any other figures for comparison) we can look at velocities. A typical rifle is ~800 m/ sec (and decreasing with range). Mercury fulminate has a VOD (velocity of detonation) of 4,200-4,800 m/ sec. It provides a far sharper shock to the dynamite than could any bullet.
     
  18. sideshowbob Sorry, wrong number. Valued Senior Member

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    Thanks. I'll buy that.
     
  19. Dinosaur Rational Skeptic Valued Senior Member

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    SideShobob: From your Post # 13
    My Post # 12 discussed issues related to this.

    That Post implied but did not explicitly mention that dynamite was designed to not detonate due to impact energy.

    A mercury fulminate detonator is designed to ignite dynamite.

    My knowledge does not include detailed chemical information relating to this issue, but is essentially correct. For the detailed pertinent data, you should use google or read a pertinent book.
     
  20. KitemanSA Registered Senior Member

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    There you go. The point is that you have to set up a shock wave in the dynamite to make it explode so the energy input must be great enough, AND FAST ENOUGH, to create that shock wave. Once the shock wave begins, it is self propogating. But as you say, the bullet is typically not fast enough to initiate that shock wave.
     

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