Yes, we know that airborne powders can produce fireballs and/or explosions. As a student (1963) I used to work a night shift during the summer vacation at Quaker Oats (puffed wheat gunner!). I'm pretty sure I saw a brief powder fireball one night on a deserted upper floor with storage bins, though I told no one, for fear I'd be laughed at.
But something has to disperse the dust first. What dispersed that coloured powder in the Taipei water park? ? Was it a propellant, as in aerosol spray cans? Might it have been liquified butane gas (boiling point -1 degrees C)?
Here's what I wrote yesterday. So far, there's no reason to change a single word, while we await the outcome of the official investigation.
Update: Sunday 28 June 11:20 French time (unrelated to Shroud)
So what caused the terrible fireball at the Taiwan water park gathering, leaving hundreds with serious burns?
So far we've been told next to nothing about the chemistry, except that a "coloured powder ignited".
If one looks at the video clip that accompanies the BBC report (see link) one sees a cloud of white vapour coming from the stage immediately before the conflagration. At a normal gig that would be the fog produced when dry ice (solid CO2) is dropped into water.
|Dry ice and water - NOT the effect used at the Taiwan water park.|
Late update (July 9) on the MIXED chemical composition of propellant liquified gases: have come across this on the BOC site:
All the mixes, from those with lowest to highest ejection pressure, are a mixture of 3 gases. propane (3 carbon), n-butane (4 carbon, straight chain) and isobutane (4 carbon, branched chain, BPt -11.7 degrees C, i.e. significantly lower than n-butane with correspondingly greater vapour pressure). In short, liquified butane is insufficiently volatile, liquid propane is too volatile. A mix of the two butanes with propane is chosen that gives the desired vapour pressure and propellant force.
Further late insertion (July 10): here's a freeze frame from a YouTube video of the disaster, showing a gas cylinder on the stage, used to eject powder.
|Gas cylinder, left of centre.|
That downward sloping delivery nozzle is suggestive of a cylinder that delivers a liquified gas as a cloud of fine vapour or adiabatically-supercooled solid particles. It's reminiscent of CO2 fire extinguishers as used in my own country (UK), except the latter are red. and have a large hollow black horn instead of a short nozzle.
If one is to look at the causes of that deadly conflagration objectively. one cannot focus exclusively on the solid powder, despite its potential fire hazard when finely dispersed in air. One must also look at the means used to propel it into the crowd. Was it really liquified CO2 that was used as propellant as stated in a minority of reports? Or was there a tragic mix up, i.e. inadvertent substitution of a highly flammable butane/propane propellant? What is the colour-coding of gas or fire extinguisher cylinders in Taiwan?
Update on that BBC report: 14:25 French time
"The fire department said the powder ,used to create a party atmosphere, may have ignited due to the heat of the lights on the stage, or from sparks from machinery.
The substance is also used in other countries. It is made of dried corn and can be highly flammable, says the BBC's Cindy Sui in Taipei.
The 519 victims were sent to 41 hospitals, and 413 are still in hospital, say municipal authorities."
Flammable solid maybe, but it still needed a propellant gas to shower it over the crowd. I still suspect itr was the propellant gas that ignited first.
Here's a freeze-frame from the video clip that accompanied the Telegraph's report:
|Video still: Taiwan water park, immediately prior to fireball|
A instant later, the white cloud of vapour (butane?) was replaced by an orange fireball.
Further reading: see the wiki entry on 'Theatrical smoke and fog".
Here's a particular (hair-raising) section, meaning not entirely clear due to missing words and/or punctuation, that may or may not be relevant to what happened in that water park. Note the reference to propane and kerosene:
An obsolete method for creating theatrical fog on-stage (although the technique is still commonly used in motion pictures) is to use a device known as a thermal fogger, initially designed for distributing pesticide, which aspirates a petroleum product (typically kerosene or propane) ignites the fuel, and then mixes in air and pesticide to create a dense fog. For theatrical purposes the pesticide is typically replaced with glycol, glycol/water mixtures, or water. This technique is similar to the smoke generators used by militaries to create smoke screens, and is generally only used outdoors due to the volume of fog produced and the petroleum fuel required.
Also from wiki, a passage from its new entry on the tragedy (my bolding)
Investigators raised the question of whether the powder was ignited by a cigarette or spark; the supplier of the flammable, starch-based powder said "if it's in dense quantities and if it's hot, it can catch fire". Organizers had purchased three tons of the powder, and wrote on their Facebook page that it consisted of cornstarch and food coloring. The powder was sprayed from the stage onto concert-goers "at high velocity".
It omits to say what method of propulsion was used.
Here's a new video clip taken from behind the stage.
The accompanying text says that high-pressure CO2 was used to propel the powder into the crowd, and that ignition had occurred at the nozzle delivering gas. That makes no sense whatsoever. As mentioned earlier, CO2 is used to extinguish fire. What seems more likely is a mix-up of cylinders, with butane or maybe propane having been used in place of CO2.
Update: 1st July 2015: Changing the subject: I have just added this comment to an Allison Pearson article on the Telegraph. (This blogger has been ridiculing the national obsession with demonising the so-called motorway middle-lane hoggers for more years than he cares to remember).
Update: Friday July 10: back to Taiwan: even allowing for cultural differences, it seems strange to this Westerner that there is so little by way of analysis, enquiry, speculation, human interest follow-upon the Taiwan disaster. Had that mishap occured in Europe or the US there would have been intense interest (bordering on fury) that something like that could have happened, killing 3 people already, and inflicting 'life-changing injuries' on scores more with those 50%+ burns. Something's not right, and maybe it's to do with those ' cultural differences'. Like the fact that the 'color play' was part of a Gay Pride festival? Have the local police investigated the possibility of foul play? Nope, I'm not into conspiracy theories, but it is the job of police to rule out 'foul play' before blithely assuming it was all just a terrible accident.
Update Saturday July 11
Here's a somewhat disturbing discovery from browsing through suppliers' sites for commercial gases. This one is admittedly propane gas only, but note the colour of the cylinder, the same light grey as the one in my Taipei video screen-shot:
Update: 15 July
Hallelluja. Wilipedia has finally recognized that some form or propulsion was needed to get all that powder airborne so quickly, and in such quantity. Here's its new(ish) edit, from which i've removed the reference numbers. (My bolding)
"The concert organizers deployed colored corn starch powder in the festivities. The method of powder application at the concert created "an extremely dense dust cloud over the stage and its immediate vicinity" people near the stage were standing "almost ankle-deep" in colored corn starch powder, and the powder was repeatedly suspended into the air using air blowers as well as compressed gas canister."
But it's still failing to be specific as regards what was inside the "compressed gas canister" as if that were of no relevance. In fact, some press reports describe it as CO2 gas, which by itself might allay suspicions (mine) that the propellant gas had a role to play. But this blogger has seen one comment that after the initial conflagration one quick-thinking individual on the stage picked up a "CO2 cylinder" and deployed it on the (reasonable) assumption it could serve as a fire extinguisher. But that created a fresh fireball, which the commenter put down to the gas having blaster still more powder into the air.
When is it going to be recognized that thee could have been a mix up with cylinders, that the propellant gas was not CO2 but a mix of liquified petroleum gases, e.g. the propane/butane/isobutane mix mentioned earlier? Wikipedia is doing us all a disservice, being more a hindrance than a help in establishing the facts, the first step of which is to rule out plausible alternatives to initial preconceptions.
Update: April 26, 2016
It's now about a year since that catastrophic fire that ended the lives of 15 young people and maimed scores more for life. I was reminded of it this morning by this article that appeared in the Telegraph.
Right at the end, we read:
An investigation showed the hottest parts of the stage lights hit temperatures of more than 1,000 degrees Celsius, while the powder's ignition point was just 500 degrees Celsius.
The "hottest part" of stage light is the electric filament, which if tungsten can get much hotter than 1000 degrees. But it's not a bare filament, exposed to air. It's encased in metal and glass, which is constructed so to be realtively cool and safe, so as not to burn anyone who inadvertently brushes again it. So why are they STILL talking about the stage light as the source of ignition?
My initial suggestion was that a cylinder of flammable gas, e.g. propane or butane, had inadvertently been used to disperse the powder. Later, I read another report suggesting it might have been a cylinder of compressed air (or maybe even pure oxygen?) that had been used, promoting ignition and combustion, which while less probable is not beyond the realms of the possible.
Naturally one needs to see a more detailed report than a single sentence in a UK newspaper, but for the moment I not only remain deeply sceptical about the "stage lights" hypothesis. I'm beginning to suspect there's been some kind of cover up and/or an attempt to divert attention from the real cause of the tragedy. If anyone reading this has 'inside information' please don't hesitate to contact, either by leaving a comment, or by direct means to sciencebod01 (at) aol.com.