blackhole89 linked me an old article on Gizmodo. It started a whole fucking chain reaction that caused me to analyze this situation and make a very long post on the Mythbusters board.
Posted by "KP9000" Cijay, thanks for gathering all those links together for me. They were great help when looking to see if this has already been posted. Seems as if this is Old Hat material...
But the purpose of this thread is not to inform. Rather, I, as a Mythbusters fan, would like to bring to light the plausibility of such a myth being tested on the show, regardless of its credibility. We've seen other "myths" that have been tested (see lots of Viral Video myths) that turned out to be hoaxes, but it never stopped the producer from airing. Why? Because it's great TV!
This has been around a long time, but just prior posting this thread, I was linked to it. The article itself intrigued me because I had just built an office chair of the same fundamental construction as the chair in this story. I also have a couple of years of experience building an office chair here and there when I used to work for OfficeMax, and currently work for Big Lots. As I sifted through the article's comments across the web, I thought about how the pieces fit together, and how each piece of the story could be explained.
So let's take a look at the most common instance of this myth. First link I came across is the Gizmodo link, which led me to the Anorak link. Both are pretty much the same thing, so I'm going to treat them as such.
In this article, you have the chair, which has apparently been blown apart. The fabric and foam padding have been severely damaged. The chair has been separated from the gas lift, which, in the article, shows almost no visible damage. On the underside of the chair, the lift trigger assembly is (although scuffed up a little bit) undamaged. The black fabric underneath is torn, revealing what looks to be a plywood of some sort. The base of the chair and any castors seem undamaged.
So, what's my analysis? Bear with me here as I take on the various arguments I have read while lightly researching this.
First off, I have no idea what's in these gas lift things, and I'm going to intentionally leave that alone as a variable. I've heard that it's just regular air, but I've also heard it could be some other gas. It's possible for both to be true, as I'm sure the construction of such a gas lift isn't generally standardized. Sure, the fundamentals are the same, but manufacturers can go about achieving the same goal in their own ways.
Let's look at what kind of explosion this is. In all cases of this incident, the gas lift turned into a rocket. Most rockets we've seen are controlled, which means the end of such a rocket (bottle rockets, model rockets, missiles, space shuttles) has been left open in anticipation of vast amounts of energy being released from it. What we have here in this article, is an obstructed rocket. On Mythbusters shows, improvised rockets (water heaters, propane tanks, fire extinguishers) tend to have tumultuous initial releases. You have the failure of the weak point, and then a steady stream of energy being released in one direction. In this article, it's no different, and I'll explain why I think these pictures look the way they do.
The seat of the chair has been obliterated, not left a clean little "hole" like what has been argued. This is because of the explosive initial failure of the weak point. The fabric, which is a horizontal and vertical intersecting weave, rips in a way that makes it look like it was "cut" by someone. The foam looks like it had certainly been in an explosion, probably ripping off in chunks.
On the underside, the lift assembly looks almost as pristine as it probably was, originally. I'm actually not that surprised, really. The inside of the assembly is probably a lot more damaged, but you can't see it in the picture. Truth is, these things are made strong, because it has to hold a ~250lb user upright in a wide variety of positions, regardless of the manufacturers' intended purpose. The outside of this assembly doesn't look too bad, because by the time the gas lift had separated itself from the assembly it was blowing a steady stream of gas, which was likely not strong enough to harm the powdercoating finish. The "damage" around the hole where the lift is positioned was most likely caused when the chair came back down on either the gas lift or some other surface. The black fabric is a loose fiber, meant for aesthetic purposes, and doesn't even have any sort of weave. In many cases, this fiber is form-embossed to give it the appearance of having an intersecting weave like most other fabrics. When the lift's stream of gas caught underneath the fabric, the embossing "uncreased", making the fiber weaker and giving more room for the gases to continue flowing between itself and the wood. The result is ripping at the pressure points, which are the screws and other chair parts. This also somewhat explains why the plastic molding on the back support didn't get much damage either, aside from the contours of the lift assembly affecting the flow of gas.
So where's the blood? This one's a mystery. In the two pictures, you can't really see much of anything in the ways of blood. If there is any, it's lost within the graininess of the photo. But it's somewhat safe to assume that this area is where the alleged explosion occurred, as evidenced by the wood pieces on the floor. One might say that the bleeding wasn't sufficient enough at this point to have left the body in the form of drops of blood. The victim might have been propelled far enough away from the chair for there not to be any around. During this short time, there might have been enough material stopping the blood from leaving the body, despite taking only an hour of bleeding to kill the victim.
This image (slightly graphic) shows another case where the gas lift didn't make such a large hole. You also can't see the underside. But this image also contributes two more factors that the Gizmodo article didn't exhibit. There's blood, enough to call this case a significant injury. From the looks of it, I don't think the victim died here, but it looks like the victim was not ejected far enough to propel him/her away from the chair. Seems they landed on the front part of the chair, where the victim had time to let blood leave the body and soak into the chair. I'd say all that probably took about 3/4 of a second before the victim stood up.
There's another important factor here. On the floor, you can see a black spot. This looks consistent with a scorch mark, which indicated that the gas lift had some kind of ignition. There's also one on the chair as well, right next to the spot of blood. This could have been caused by the scorching the gas lift did to the victim's rear, that when s/he came back down, the scorch mark rubbed off onto the chair.
This also implies that the lift blew both of its ends off. I'm not sure what to make of that, because I'm not a rocket scientist, and I am not sure if such an ignition as proposed could physically work. I'll give it a try though. It seems to contradict my understanding of what might happen in this situation. If one end of the lift gets blown off, wouldn't the gas escape from that end and thus greatly reduce the pressure from the other end? Perhaps the ignition caused both ends to fail evenly?
Another image, this time inside what looks to be a garage, a barstool exploded, leaving scorch marks. I'm not sure if that's dried blood in the background, but the little girl sitting on this chair did indeed bleed (slightly graphic again) and lived, as far as I know.
Quite frankly, the number of threads that this particular myth has generated is a pretty decent collection of threads. I'm hoping this thread gives the myth more of the attention it deserves, and possibly a chance of being featured in an upcoming episode of Mythbusters!
I'll give you guys the links I found, that cijay found.
This myth bears somewhat close resemblance to the exploding bumper myth. It's not really too much the same in regards to how I think the gas lift exploded compared to how Jamie and Adam explained their myth, but I think this myth has just as much potential to be as good or better than the exploding bumper myth. I believe that this myth should be explored and featured, as this Average-Joe does not have the science, tools, experience or safety in place to do so myself. I also have read throughout my research on this myth that some people are scared of their chairs and have opted to "stand up" while posting their replies. This suggests that a certain fear has spawned from this myth. I also want to point out that if this myth is real, it might help the victims of these accidents understand what might have happened and possibly have legal repercussions that most likely will favor the victims and/or their families.
It's been said that some remnant gases are making their way into the pistons. These gases, although normally not present in most manufacturing processes, somehow managed to be mixed in the right amount with normal air. Once you sit on the chair, the gases compressed, and once it reached its flash point, it ignited, much like a diesel engine.
Given that these people have sat in their chairs many times before, I'm not sure why the pistons would explode in one instance and not the others. Perhaps wear and tear has an important factor.
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The gases actually igniting does sound rather far-fetched to me. Without having researched it more deeply, my assumption always was that it just was a rather explosive rupture of a weakly built cylinder under pressure.
God damn it when I saw your avatar I thought Colin had come back.
I call bullshit on the gas ignition.
At least you're trying to stay on topic.
Although the gas ignition is indeed far-fetched, think of how many of these gas lifts have been manufactured. More than all of the cell phones in the world combined. Think some of them could have been so horribly faulty that they had a failure such as the one(s) in the article?
God damn it when I saw your avatar I thought Colin had come back.
I call bullshit on the gas ignition.
Come on man, I've had the same avatar for about five years now. All that changes is the color from time to time..
K, I'm done with offtopic too now.
So, do you have an idea what sort of gases would be capable of hitting their flashpoint with just the force of an average person sitting down? And, while I'm sure there is no standard on the sort of gas used, I would assume they use argon, or something similar that does not burn, specifically to prevent such occurrences.
Anyway, I'll tie this off with a link to the patent, which also does not appear to specify what gas to use, but might have something useful in it.
Adjustable gas cylinder chair control
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