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Detonation wuz Things not to wear when welding

Now THIS is why I love this list. Nicely done.
Cathy


>From: "Brian Haygood" <haygood@myway.com>
>Reply-To: haygood@myway.com
>To: scirocco-l@scirocco.org
>Subject: Detonation wuz Things not to wear when welding
>Date: Mon, 12 Apr 2004 01:13:59 -0400 (EDT)
>
>
>There is also some engine related stuff in the last half of this! Lol.
>
>That original myth is just that.  I've done a good bit of research over the 
>last few months on combustions, detonations and explosions.  A plastic 
>lighter, even though pressurized, shouldn't do any more than burn 
>dramatically.  It would not explode for a few reasons.  Inside a lighter 
>there shouldn't be any considerable amount of oxygen (if there were, you 
>might be at risk for the thing igniting internally during use), so a flame 
>would not burn inside the lighter body to explode the lighter.   If a flame 
>did occur in the lighter, it would be deflagration, which is a slowly 
>moving flame, like lighting a pool of gasoline.  It's cool, but you don't 
>get anywhere near the "stick of dynamite" force until you get a detonation. 
>  A deflagration becomes a detonation when the flamefront reaches the speed 
>of sound.  There you get a sonic shockwave that concussively ignites a 
>large amount of fuel mix all at once, resulting in dramatically higher 
>pressures.  Enclosed deflagrations typically result in pressures 6 to ten 
>fold that of the original pressure.  Detonations are way way beyond that.  
>Assuming there were a flame inside the lighter (which there couldn't be b/c 
>of lack of oxygen), a flamefront requires a certain distance to accelerate 
>and progress up to the speed of sound, determined by the type of fuel, 
>pressure and container/flamefront geometries.  Suffice it to say there 
>isn't enough room in a lighter for a detonation to occur in propane or 
>whatever else is in those things.
>
>Given the actual case, that there is no oxygen to burn inside a lighter (or 
>hardly any, to be sure), the worst that could happen would be something 
>perforating the plastic shell of the lighter, igniting it simultaneously, 
>and guess what you get.  A flame.  You know, like you always get when you 
>light a lighter.  No torso removing action here.   Maybe it could spew 
>lighter fluid a bit and get a decent fire going, and I can see that being 
>pretty bad.
>
>So I promised something "on topic", right?   If you have a combustion in a 
>combustion chamber of an engine, hopefully you have a deflagration.  If you 
>have a really fast burning fuel, or if you have a really large diameter 
>piston, then the distance from the end of the spark plug to the ends of the 
>cylinder might exceed the minimum detonation-to-deflagration distance for 
>the given fuel mix and pressures.  If that happens, you get detonation in 
>your engine. The rapid combustion creates a big pressure spike that is 
>audible.  The sound is called "knock" and a knock sensor is basically a 
>microphone used to listen for it. Detonation became a problem in WWII 
>aircraft engines as piston sizes grew dramatically.  The solution was to 
>use two sparkplugs, effectively cutting the distance the flame front 
>travels across the piston in half, and keeping this below the 
>deflagration-to-detonation transition (DDT) distance.  Modern piston planes 
>still have twin spark, and it is kept around as part of a redundant spark 
>system that is supposed to save your butt if one magneto system fails.  
>While it will do that, that was not it's original purpose.  Personally, I 
>don't think its worth keeping because I've never heard of someone no 
>warning of electrical trouble (batt. light) long before their engine dies 
>from lack of electricity, but then I'm not the FAA.
>
>Octane is added to fuel because it doesn't burn as quickly as gasoline.  
>This slows the reaction rate, which increases the distance to the 
>deflagration-to-detonation transition (DDT).  This keeps your engine from 
>experiencing detonation.  With the reaction rate slowed, you are free to 
>run higher compression.  The slower reaction provided by octane can also 
>lead to a more even burn throughout the ignition cycle, which often leads 
>to a more efficient running engine (slightly, and I know a lot less about 
>that end of things).
>
>So detonation, or knock, is also completely separate from pre-ignintion.  
>That's when a poorly timed spark, or a hot ember on top of a piston (or 
>such) ignites the mixture before it's time, and the flame front whacks into 
>the top of the piston while the piston isn't free to move out of its way.  
>It's actually usually less violent than detonation (unless it happens so 
>early that is causes a backfire and fries a turbo or something).  I think 
>octane helps with that by slowing the reaction rate, allowing (and also 
>requiring) more spark advance to get the flame and piston well 
>synchronized.
>
>Hope that was long and rambling enough for everyone!!! If I have missed or 
>flubbed up some of this, you are all welcome to have a field day correcting 
>me.  I'd want nothing less!
>
>Cheers,
>Brian in Texas (not Pittsburgh)
>
>
>
>
>  --- On Sun 04/11, David Utley < mr.utility@highstream.net > wrote:
>From: David Utley [mailto: mr.utility@highstream.net]
>To: ats@longcoeur.com, smithma7@yahoo.com, scirocco-l@scirocco.org
>Date: Sun, 11 Apr 2004 11:39:55 -0500
>Subject: RE: Things not to wear when welding
>
>That reminds me of that Darwin award winner, that used a 22 unused shell 
>as<br>a fuse in the fuseblock of his ford pickup (for the lights)...  
>Teseticular<br>removal at high speed, which then hearly killed his 
>passenger as he wrecked<br>the truck...!<br><br>I hate that when -that-- 
>happens...<br><br>David<br><br>-----Original Message-----<br>From: 
>scirocco-l-bounces@scirocco.org<br>[mailto:scirocco-l-bounces@scirocco.org]On 
>Behalf Of Patrick Bureau<br>Sent: Sunday, April 11, 2004 7:55 AM<br>To: 
>'Mike Smith'; 'car'<br>Subject: RE: Things not to wear when 
>welding<br><br>Don't throw ammo in a fire, unless you don't value your 
>life.<br><br>I know your joking around, but hundred of children and young 
>men, each year<br>end up in hospitals and sometimes die in accidents, from 
>people tossing<br>ammunition into fire camps or bond fires because "its 
>cool to hear the<br>"BANG", and this list should not let such a comment go 
>without a warning<br>(there are younger folks on this list that may get 
>ideas from your words),<br>not to mention the risk of the live round flying 
>through the camping ground<br>with nothing more than "tents" as barriers, 
>you can definitely hurt a lot of<br>people with such a prank. Sorry if I am 
>preaching here, but I think someone<br>had to speak up on that 
>subject.<br><br>DO not put ANY ammunition in a fire period.<br><br>-<br>ATS 
>- Patrick Bureau - http://ats.longcoeur.com -<br>A1 eBay Sales: 
>http://tinyurl.com/22e5b<br><br><br>->-----Original Message-----<br>->From: 
>scirocco-l-bounces@scirocco.org<br>->[mailto:scirocco-l-bounces@scirocco.org] 
>On Behalf Of Mike Smith<br>->Sent: Sunday, April 11, 2004 1:00 AM<br>->To: 
>car<br>->Subject: Re: Things not to wear when welding<br>-><br>->For the 
>camping folks (me included) do we want to be invited<br>->back to Cowen?  
>This sounds like fun... <evil laugh>I can<br>->bring ammo</evil 
>laugh><br>-><br>->Mike<br>->sshh!  There's liberals afoot!<br>->Scourge 
><scourge@cogeco.ca> wrote:<br>->lol, I've done that.....one of my freinds 
>threw a full can of<br>->wd40 into a campfire...almost burnt down a few 
>trees.<br>->I always liked cans of stew 
>best......lol<br>-><br>-><br>->-George<br>-><br>->----- Original Message 
>-----<br>->From: "C Boyko"<br>->To:<br>->Sent: Saturday, April 10, 2004 
>7:48 PM<br>->Subject: Re: Things not to wear when 
>welding<br>-><br>-><br>->> If you want kablooey, toss an unopened Coke can 
>into the<br>->old campfire.<br>->> Ask me how I know about this, oh yeah, 
>I'm a mother of an<br>->idiot. Does<br>->> a really good job on the tents 
>too, all that hot carmelized<br>->liquid and<br>->> shards of aluminum. 
>DON'T try this, okay? It's a wonder soft drink<br>->> 
>manufacturers<br>->don't<br>->> have a warning about it actually.<br>->> 
>Cathy<br>->><br>->><br>->> >From: Dan Smith<br>->> >To: 
>scirocco-l@scirocco.org<br>->> >Subject: Re: Things not to wear when 
>welding<br>->> >Date: Sat, 10 Apr 2004 16:02:25 -0700 (PDT)<br>->> ><br>->> 
> >Entirely different situation. When tossing lighters, it<br>->works by 
>the<br>->> >top metal part breaking and sparking, causing the fluid 
>to<br>->both pour<br>->> >out and light. It's about the same as pouring 
>lighter fluid on the<br>->> >ground and lighting it. Remember lighters are 
>pressurized and when<br>->> >you put a small piece of glowing hot metal 
>into them, then<br>->they can<br>->> >explode. Think of it this way. 
>Imagine shoving a red hot<br>->nail into a can of 
>hairspray.<br>->Kablooey!<br>->> >Take a hairspray can and break the top 
>off so the gas can freely<br>->> >escape<br>->and<br>->> >light it on fire. 
>Not much happens besides a firely blaze.<br>->> ><br>->> >Dan<br>->> 
> ><br>->> >chris gonzalez wrote:<br>->> >I call BS on that myth. I used to 
>explode plastic lighters<br>->when I was<br>->> >a<br>->kid<br>->> >by 
>throwing them at the ground. Just a big flame out, like<br>->when 
>you<br>->> >pour lighter fluid on a BBQ. Absolutely no concussive force. 
>You<br>->> >could definitely get burned, but doubt you'd get 
>killed.<br>->Let's call<br>->> >Mythbusters....<br>->> ><br>->> >John Klun 
>wrote:Dan and y'all:<br>->> ><br>->>
>  >The story below is quite true. In 1966 when the first BIC plastic<br>->> 
> >lighters came out, lots of sailors bought them because they were<br>->> 
> >cheaper than Zippos. A Naval Safety Bulletin was issued to<br>->the 
>entire<br>->> >Navy in late 1967 early 1968 forbidding any one who 
>was<br>->welding from<br>->> >keeping the plastic lighters in their breast 
>pocket. The Bulletin<br>->> >referred to an accident that occurred to a 
>sailor who was welding<br>->> >ashore. (At that time, the welding 
>'leathers' were more<br>->like butchers<br>->> >aprons- covered most of the 
>body but did leave the breast pockets<br>->> >unprotected.) A spark from 
>the sailor's welding torch struck his<br>->> >breast pocket, burned through 
>to the lighter and it caused the<br>->> >lighter to explode. The bulleting 
>referred to the<br>->resulting explosion<br>->> >as equivalent to the 
>explosive force of a stick of<br>->dynamite resulting<br>->> >in the 
>sailor's death. I do know that on our ship, any sailor<br>->> >assigned to 
>welding and repair had to be 'inspected' by<br>->his leading<br>->> >P.O. 
>or his Division Officer before being let loose with a<br>->welding 
>torch....<br>->> ><br>->> >Dan Smith wrote:<br>->> ><br>->> > > He also 
>knew of people (or stories of said people) who<br>->always 
>kept<br>->their<br>->> >lighter in their breast pocket while welding and an 
>errant piece of<br>->molten<br>->> >metal would land on/near the lighter, 
>melt through it and blow off<br>->> >the person's torso.<br>->> > ><br>->> 
> > >Dan<br>->> > ><br>->> > ><br>->> ><br>->> ><br>->> 
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