Fireworks: why don't they burn people?

Factual Questions
1

All the time you hear about people being terribly burned from fireworks, which seems pretty obvious: deliberate explosions of ultra-hot metal would seem to have that effect. So why doesn’t this happen with the debris from professional firework shows?

Let me explain. Tonight I was enjoying the Concours des feux d’artifice SAQ Mondial, and at several points during the night’s presentation, I saw that “low-flying” explosions were letting lit pieces of firework hit the ground.

At one point, they were firing off gigantic shells high into the sky, and one exploded very near the ground. I don’t know if this was deliberate, or an accident; but in any case, the show continued uninterrupted, and I didn’t hear anything on the radio (the musical accompaniment is broadcast live) that would indicate massive burns in the stands, etc.

(Bear in mind that the launch site is surrounded by stands full of people who paid $30 a pop to be there. The plebs like me crowd onto the Jacques-Cartier Bridge, which is closed for the night.)

So how come these shards of hot metal hitting the ground and the stands cause burns and fires?

2

WAG…
They’re set off far enough away from people that if something went awry, the audience has some reaction time to stay safe or get out of harms way. The pyrotechs also clear themselves after lighting the fuse. It seems to me that 90% of firework related injuries are from people who are setting off illegal stuff, have no professional trining, and are either too drunk or too dumb to get out of the way after lighting the fuse.

That’s not to say that accidents in a professionally produced show don’t happen, but in general, I’d think that they take all necessary precautions to prevent spectator harm.

3

of course that last sentence should read “don’t cause burns and fires”.

4

Also note that fireworks are not very rich in metal. People are usually injured by burning powder (some of which can be metal); shrapnel is usually left out of the mix.

5

Hot metal? I don’t think there is any hot metal in them as they use metal in powder form.

Also, notice if you look at a spark piece real carefully that the front is not burning, the back of it is & the front part is usually what hits people.

6

My family went to see the July 4 fireworks in DC down on the Mall. We were under the Washington Monument facing the Reflecting Pool, where they’re launched - I’ve never been that close to fireworks before. That said, surrounding the launching area was an off-limits zone, which seemed large enough to keep prematurely exploding shells from hitting viewers. But the winds were such that we got hit with a lot of ash - at first we thought it was rain, but then we looked and saw the black soot! Still worth it for a great show.

7

If you are reffering to what are known in the trade as “stars”, then that’s not accurate. Stars are small balls of compressed gunpowder with various powdered metals and metal salts mixed in to achieve the desired color. They burn from the outside inwards–once they ignite, the whole exposed surface begins to burn almost immediately. If one hit you while it was still burning, it would certainly leave a mark. Their burn time is very short, however, and the fireworks are normally launched to a high enough altitude (typically 800-1000 feet) so that all the stars have completely burned long before any could reach the ground still burning.

8

matt_mcl when I got my firework certification stuff, there was a bald guy who had a crater in the back of his skull where an undetonated fireworks shell-casing thing had blown into the back of his head. Which is why if you’re on the crew loading the mortars, you’re supposed to wear a fireman’s coat and helmet – a fireman’s helmet helps to protect you from behind rather than just from above.

Indeedy-do they are extremely dangerous and can cause injuries if you’re too close and something goes wrong.

Occasionally there is a misfire and things pop when they’re still close to the ground (believe me, when you’re right there next to the mortar and the firework goes boom only 8 feet up rather than 800, it’s quite the rush – an OMG I’m going to die! kind of rush!)

There are two main charges. Boom#1 (sounds more like “foop!” actually) launches the firework from the mortar into the sky. As it’s going up, the fuse keeps burning until it gets to Boom #2 – the one that makes everything burst outwards in a pretty star – the stars in turn catch fire, sometimes have mini-booms of their own, and make pretty twinkles in the sky.

Sometimes there is something wrong with a charge so the time bewteen Boom #1 and Boom #2 is quite short. That’s why you really want to be wearing a fireman’s coat and helmet when you’re by the mortars. You can get hit by the stars. You can get burnt if the powder has ignited. And if you think it hurts getting shot with a paintball – imagine having a star blown at you (as the aforementioned bald guy in my class with the crater in his head). They’re mostly power wrapped in cardboard and paper but still, they travel at quite the high rate of speed and are compacted into tight wads of death!

Maybe I’ve just been lucky, but in all the cases that I or my friends/coworkers know of that Boom #2 happened early near the ground, there wasn’t enough time for the stars to ignite and burst into hot, balls of fire. So most of the danger was from the projectile effect.

There are standards for how much space there must be between the audience and the mortars for high level display fireworks for just that reason. The distance depends on the class of fireworks.

Fireworks supervisors must take out a minimum of a million dollars in insurance to cover accidents (oh, say like setting the crowd on fire, or putting someone’s eye out).

After the display is over, there is a very, very, VERY thorough search for any shells that may have dropped unexploded.

In my class, they warned us with the anecdote of a kid who blinded himself two years after a fireworks display. He’d been on the volunteer “search for unspent shells” squad and found one. Rather than turn it over, he brought it home, forgot it in the garage, found it a couple of years later, broke it open and dumped the powder in a glass jar and threw in a match. :eek:

9

“After the display is over, there is a very, very, VERY thorough search for any shells that may have dropped unexploded.”

Why search? They should have put some tape over the top of each mortar, so they know which ones didn’t go off…

BTW, our local FD uses an auto flare to set the show off, they are so out of date on this…

10

Handy, I think he’s referring not to unfired mortars, but the ones that did launch but didn’t go off once in the air, and then landed somewhere.

11

They do, handy. The mortars have aluminum foil taped over them–but this is mainly to protect the shell inside for being prematurely fired by a neighboring shell being launched, rather than as an indicator that the shell was expended. They search for shells whose lift charge did fire and launch the shell, but the burst charge failed. It’s rare, but it happens.

12

ahem She is referring to the duds that dropped from the sky.

I was also one of only a few women who took the certification course to get a Fireworks Supervisor Card, and the other women in the class were all my cohorts.

Handy each mortar is inspected after each round is fired to prevent any accidents. Example, if a bunch of paper and powder is still burning at the bottom of a mortar, you don’t want to drop a fresh charge into it. That would produce… er… “unexpected results.” (And no, we don’t stick our faces over the barrel and look inside, that would be incredibly stupid.)

I was actually a little surprised by the number of charges that didn’t quite behave as planned. It gave me a quite a respect for the dangers unpredicatablity of pyrotechnics. Watching them glitter in the sky, you don’t realise that the charges are far from precise. It was actually pretty scary.

You’d hear “foop!.. pow!” and sigh with relief.

If it was “foop!–POW!” you’d cringe and hope nothing would hit you.

I’d never got hit, but I always imagined it would be like a canon ball.

13

my bad

14

No worries. :slight_smile:

15

I have been burned by fireworks. A small price to pay for winning many bottle rocket wars!

Just as my many horrible hot oven and grease spatter burns are a small price to pay for fresh bread and fried food!!!

And then there’s that whole thing where I might be careless around fire.

16

Bottle rocket wars? Are you insane? You are are aware that some of them can and do explode violently, and there is no way to tell the difference between those that do and those that don’t. Kids, please do not be like j.c. Burning your face off or getting your eardrums ruptured is a big price to pay for a little fun.

17

If used the same ones we used, they are hardly powerful enough to burn your face off or rupture your eardrums. These are very small, light, not very fast, have very little impact force, and are about as scary as yelling “boo!” at somebody.

I have shot many, many, gross of these things, been on the receiving end of at least as many, and none of us ever got anything but black (not burned, just sooty) fingers for our efforts.

18

I would like to proudly add that I was burned by sparks (or whatever) during a fire works show celebrating year 2000eve (in New Zealand near Lake Rotoiti - perhaps these guys weren’t quite as professional as they claimed).
Hurt like hell, to tell the truth…

19

" I was also one of only a few women who took the certification course to get a Fireworks Supervisor Card, and the other women in the class were all my cohorts."

Lucky you. Most of my family worked for Pyrospectaculars. I wanted to work for them but they wanted to know how I would hear people calling off the shot. 'Yo handy, look out" :slight_smile:

I did quite a number on my hand years ago using some pyro chemicals & a blender.

20

The standards are set by the National Fire Protection Association (NFPA). The relevant document in this case is:

This document will run you about $20 to purchase. (OTOH, Google manages to pull up a copy for free. Oops.)