LAPD blast containment truck fails, seventeen people injured 6

[jrs87]

https://www.dailymail.co.uk/news/ar...illegal-fireworks-LA-goes-terribly-wrong.html

Someone did not read the manual.

 

[dik]

The 500 lb lid was found several blocks away... range was a little more...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[TugboatEng]

Rocket scientists and cannoneers? Get these guys a defense contract. They have done the impossible by developing an improvised rocket device as well as a barrel-less cannon.

 

[RedSnake]

The LAPD has not publicly identified the manufacturer of the detonation chamber, despite repeated requests.

At least in this thread I think we came to the conclusion that there could only be one manufacturer of this particular model of blast chamber.
Even if we don't know the exact model and the data about how many times you can blast a certain amount before you need to scrape it seems to vary between different places.
It seems strange that the LAPD will not give out that information unless they are looking for a subcontractor for certain parts.

/A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[JStephen]

https://www.yahoo.com/news/los-angeles-bomb-squad-miscalculated-053958476.html

"Bomb technicians estimated the weight of the explosives to be 16.5 pounds. without using a scale, Moore said. The vessel is designed to take, at most, 25 pounds for a single-use and 15 pounds for multiple uses. An investigation by The Bureau of Alcohol, Tobacco, Firearms and Explosives National Response Team found that the actual weight of the explosives was over 42 pounds."

 

[dik]

There goes your factor of safety...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[LionelHutz]

My first thought was that it makes no sense to guess to the limit when they could take more time and do multiple explosions. My next thought was that this happened on the holiday weekend so they rushed it to get home. But, checking the date again it was a few days too early for that excuse.

 

[dik]

You would think that those guys, if anyone, would know what they were dealing with.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Mark R]

At least we now know that there wasn't a problem with the containment vessel, there was just a problem with people using it! When you put a lot more explosives in the device that it was designed to contain it's bound to cause problems! I'm surprised that the device itself doesn't have some way of weighing the devices put inside of it but it probably will after this experience!

 

[byrdj]

definately no one on the team had this mantra

“when you can measure what
you are speaking about, …
you know something about it;
but when you cannot measure it, …
your knowledge is of a meagre
and unsatisfactory kind…” Lord Kelvin 1883

But in their defense, taking a "bomb" apart so you can measure just the explosive would not be a job anyone would like

erring on the "safe" side should be a golden tule

 

[spsalso]

I do wonder if confining the material made it worse.

How bad would it have been if they'd tossed the stuff in a Weber, doused it with kerosene, and tossed a match.

True, a populated area may not be the best place for such an experiment. But I'll also bet you could've sold tickets.


spsalso

 

[TugboatEng]

Some explosives detonate by heat, others percussion. A fire is not a one size fits all solution here. I'm sure the counter charges are expensive. Department was probably trying to save money.

 

[JStephen]

The explosives don't have to detonate by heat, if they just burn up, that's okay too.
Call out one of those pier-drilling rigs, dig a shaft 50' deep, shovel everything in, sell tickets, throw in the gasoline and the match.

 

[Spartan5]

I want to know what they blew up the other 42 times.

 

[TugboatEng]

Unattended luggage from the airport.

 

[IRstuff]

It seems to me that a factor 2 is not adequate for such a catastrophic possibility. There's at least a 50% difference in detonation pressure amongst various explosives such as PETN and Semtex, so one would think that the safety margin would need to be more like 4x or higher, to account for explosive variability, errors in weighing, potential errors/defects in operation/construction.

I don't know how accurately the bomb squad can assess the actual explosive, i.e., 25 lb of PETN vs. 25 lb of Semtex

Also, there's literature on how the detonation velocity, which is dependent on detonation pressure, is a function of the amount/density of explosive

https://www.osti.gov/servlets/purl/5560850

https://aip.scitation.org/doi/pdf/10.1063/1.5044989

seems to say there's at least around a factor of 2 in detonation pressure between various explosives.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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[RedSnake]

That is something I have been thinking about what is the most "explosiv" material per gram is it TNT or Military C-4.
Both TNT and Military C-4 is used as a measurement of what the container can take.
But what is that the most explosive thing per gram that someone can be put tougher when making explosivs.

And even if they only X-rayed the cans and made a estimate, it hade been safer to assume it was the maximum amount that could be put in them, that where the weight.

larger explosives — which were about the size of a soda can with a fuse — had about 1.5 ounces (42.5 grams) worth of flash powder. Federal authorities who weighed the larger ones sade they were about 5 ounces (142 grams).

In SE a soda can is 33 cl if you fill it up with flash powder 5 parts potassium nitrate, to 3 parts aluminum powder, to 2 parts sulfur
The potassium nitrate and sulfur aprox (2gram/cm3) = 46,2 gram aluminum powder aprox (1 g/cm3) = 9,9 grams.
The powder or can would weighed around 56,1 grams.

So there is some miscalculation on someone's part or maybe your soda cans are not 33 cl.
Or it wasn't potassium nitrate, aluminum powder, sulfur flash powder.

/A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[itsmoked]

I think the whole thing is run incorrectly. If you have a pile of things to blow up why would you not blow up a single one to take it's measure. Look at the pressure wave data generated and looking at some chart that pukes out TNT equivalence. Then there is zero explosive percentage estimation, zero weighing, and zero guessing of TNT equivalence. A small device would probably exclude the need for any kind of detailed inspection of the chamber post detonation.

That process would dump out, "You can depose of 12 devices at a time".

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Alistair_Heaton]

to be honest even with my extreme low level knowledge of such things i can't understand why you would want to blow fireworks anyway.

They are mostly powder.

The easiest way of dealing with powder is to soak it with water which then kills the saltpeter and for ever more its useless. The biggest issue when I was involved in doing that was the waste water afterwards had to be disposed of because the water board didn't want such a huge amount of salty water screwing up the sewage system.

 

[byrdj]

I think calling the expolosive "fireworks" is to misinformation the facts possible militarty (terorist) grade high explosives were mixed with possible proffesional grade fireworks

 

[Alistair_Heaton]

yes but if the fireworks are useless there is no initiator for the HE which is pretty harmless then. You can throw it on a fire and it won't go bang. You can even eat it if you want.