Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Fighting fires with sound frequencies

washingtonpost.com

Post reply on HN
Print view View original

21–30 of 32 posts

Re: Fighting fires with sound frequencies

#21

Post by Trisell »

IshKebab wrote: post #19

It sounds like they're basically blowing the fire out, which is why it only works on really easy-to-blow-out flames. Good luck blowing out a forest fire!

I completely agree. I bet I could take a leaf blower, and with the right application of air on that size of a fire, blow it out. On a fire that small, it doesn't take much air to change the fuel-air mixture creating a fire that won't burn.

Best illustrated when you throw a match at a small container of gasoline, and it flies into the gas, and is put out by the fuel. But if you slowly move it towards the gas, eventually it will start a fire, because the match passes slowly enough through the right air mixture to allow the gas to burn.

Re: Fighting fires with sound frequencies

#22

Post by [deleted] »

Trisell wrote: post #16
Someone1234 wrote: post #7

I've been thinking about this exact concept since the Mythbusters tested it. I'm glad someone has gone out and prove it has legs/pushed it forward. While I could see the benefit for the scenarios they listed (aircraft, space shuttles, etc) I actually think the real killer use could be for forest fires. With forest fires you're constantly running out of water, and the only way to ship it the location it is needed is o…

Lets dispel a few myths: Fire has to have three things to burn, Fuel, Oxygen, and Heat. This is called the fire tetrahedron, and is the primary theory behind fire fighting. If you eliminate one, then the fire is unable to maintain a chemical reaction, and goes out. With forest fires you're constantly running out of water, and the only way to ship it the location it is needed is often multi-hour drives (which consume…

[deleted]

Re: Fighting fires with sound frequencies

#23

Post by mentat »

[deleted] wrote: post #22
Trisell wrote: post #16

Earlier quoted context omitted.

Lets dispel a few myths: Fire has to have three things to burn, Fuel, Oxygen, and Heat. This is called the fire tetrahedron, and is the primary theory behind fire fighting. If you eliminate one, then the fire is unable to maintain a chemical reaction, and goes out. With forest fires you're constantly running out of water, and the only way to ship it the location it is needed is often multi-hour drives (which consume…

[deleted]

I'm pretty sure you didn't read or take seriously his post. He pointed out specific reasons why water wasn't relevant and that the suggested method didn't scale. Please reconsider and edit your post as your tone is far more problematic.

Re: Fighting fires with sound frequencies

#24

Post by daeken »

[deleted] wrote: post #22
Trisell wrote: post #16

Earlier quoted context omitted.

Lets dispel a few myths: Fire has to have three things to burn, Fuel, Oxygen, and Heat. This is called the fire tetrahedron, and is the primary theory behind fire fighting. If you eliminate one, then the fire is unable to maintain a chemical reaction, and goes out. With forest fires you're constantly running out of water, and the only way to ship it the location it is needed is often multi-hour drives (which consume…

[deleted]

I've flagged this comment for two reasons: Your tone is unnecessarily hostile, and you haven't provided any additional information. This is pure flamewar material (and may actually mark the first time I've seen a flamewar about offline flames!); please consider a more constructive approach to the conversation.

Re: Fighting fires with sound frequencies

#25

Post by Trisell »

jerf wrote: post #17
Someone1234 wrote: post #13

Earlier quoted context omitted.

> No, this a different concept and is a different mechanism at work. They both use shockwaves to smother the fire. Seems like the same mechanism to me, and also a very similar concept. No clue why you posted that then almost contradicted that line with: > They both do retard access of oxidizer of course, but then so does nearly every other extinguishing method, starting from fire blankets. Seems like you just wanted…

"They both use shockwaves to smother the fire." That speaker isn't emitting "shockwaves": http://en.wikipedia.org/wiki/Shock_wave That's obviously a standard speaker cone and is entirely subsonic. I would have to agree that a true high-explosive shockwave is a beast of a different color.

Using dynamite to 'blow out' the fire by forcing the burning fuel and oxygen away from the fuel source.

It sounds to me like they were using the explosives to essentially force a change in fuel air mixture. Essentially the same idea as when the wind blows out your lighter or match. Just way more fun, because explosives. :D

Edit: Quote is from Oil Wikipedia Article above.

Re: Fighting fires with sound frequencies

#26

Post by Trisell »

Trisell wrote: post #21
IshKebab wrote: post #19

It sounds like they're basically blowing the fire out, which is why it only works on really easy-to-blow-out flames. Good luck blowing out a forest fire!

I completely agree. I bet I could take a leaf blower, and with the right application of air on that size of a fire, blow it out. On a fire that small, it doesn't take much air to change the fuel-air mixture creating a fire that won't burn. Best illustrated when you throw a match at a small container of gasoline, and it flies into the gas, and is put out by the fuel. But if you slowly move it towards the gas, eventual…

PSA I don't recommend doing this. We did this in the fire service as a training example. We also had full body bunker gear, helmets and the guy lighting the gas was also wearing a SCBA to prevent any sort of flash fire injuries. Gas and fire are really, really dangerous.

Re: Fighting fires with sound frequencies

#27

Post by 12thr0wit »

IshKebab wrote: post #19

It sounds like they're basically blowing the fire out, which is why it only works on really easy-to-blow-out flames. Good luck blowing out a forest fire!

There's a limit to db, something like 190, where the noise creates a vacuum followed by a blast wave, followed by a vacuum and so on.

Get something that makes that kind of noise next to a fire, then something on the other side of the noise (away from the fire) that either dampens or cancels the noise travelling away from the fire, and they might be onto something.

Re: Fighting fires with sound frequencies

#28

Post by bsder »

Trisell wrote: post #16
Someone1234 wrote: post #7

I've been thinking about this exact concept since the Mythbusters tested it. I'm glad someone has gone out and prove it has legs/pushed it forward. While I could see the benefit for the scenarios they listed (aircraft, space shuttles, etc) I actually think the real killer use could be for forest fires. With forest fires you're constantly running out of water, and the only way to ship it the location it is needed is o…

Lets dispel a few myths: Fire has to have three things to burn, Fuel, Oxygen, and Heat. This is called the fire tetrahedron, and is the primary theory behind fire fighting. If you eliminate one, then the fire is unable to maintain a chemical reaction, and goes out. With forest fires you're constantly running out of water, and the only way to ship it the location it is needed is often multi-hour drives (which consume…

In addition, very few people have experience with big fires.

It is hard to appreciate the difference between a small localized fire (energy drops off quadratically with distance from fire) and a small line brush fire (energy drops off only linearly with distance from fire) without personal experience.

I can't even conceive of the difference between a small line brush fire and one of the 40-50 ft seasonal conflagrations in Australia or Southern California.

Re: Fighting fires with sound frequencies

#30

Post by varjag »

Someone1234 wrote: post #13
varjag wrote: post #12

Earlier quoted context omitted.

No, this a different concept and is a different mechanism at work. They both do retard access of oxidizer of course, but then so does nearly every other extinguishing method, starting from fire blankets.

> No, this a different concept and is a different mechanism at work. They both use shockwaves to smother the fire. Seems like the same mechanism to me, and also a very similar concept. No clue why you posted that then almost contradicted that line with: > They both do retard access of oxidizer of course, but then so does nearly every other extinguishing method, starting from fire blankets. Seems like you just wanted…

You misunderstand the concept of shockwave, and no, there is no contradiction in my statement. I'm pretty sure you understood the sentence, but decided to move the conversation towards my personal behavior.
Post reply on HN