What Is in Road Flares? | Hacker News Reader

What Is in Road Flares?

spiegl.org

39 pointshyperific33 comments

For extraction, you'd want to use different solvents that have different dissolving properties - usually something like water, ethanol, DCM, acetone, MEK, methanol, toluene or whatever.

For strontium, it looks like it's relatively soluble in short chain alcohols (methanol/ethanol) compared to the other two, so you'd crash out the potassium perchlorate by dissolving the mixture in water, then reducing the temperature to cause perchlorate to drop out of solution, then mix in a moderate amount of methanol to crash the potassium nitrate out, being left with a reasonably pure strontium nitrate, that you could then hot filter and recrystallize in anhydrous methanol if you wanted >90% purity. One or two rounds of recrystallization will leave you in the high nineties, probably above 97%.

This is a classic chemistry workup kind of problem and there are interesting engineering challenges embedded in it.

Of course... practical people just buy technical grade strontium nitrate and make fireworks out of it directly, as the article says.

This page reads like an exasperated response to constant discussions and requests for how to extract strontium nitrate from road flares, and emphasizes that it is hard and pointless in the first place. I never noticed such discussions, but maybe it's outside of my bubble! Quite an amusing read nonetheless.

That sounds like the kind of discussion that might show up on the venerable sciencemadness.org

>Some older flare formulations also had things such as pitch, asphalt, wax, tallow, potassium chlorate and black powder. Those are not likely to be part of modern flare formulations.

Most of the formulations in the table have charcoal, potassium nitrate or other oxidiser, and sulfur. Surely, to say they don't contain black powder is semantics, when they contain the ingredients of black powder?

You can look at pasta and bread the same way.

Potassium perchlorate and powdered aluminum can be used to make flash powder. Just because road flare contains both doesn't mean it's going to explode in your hand.

I don't know why this makes me think of it but the coolest "burning" thing has to be an "Oxygen Candle"

https://en.wikipedia.org/wiki/Chemical_oxygen_generator#Oxyg...

https://minearc.com/oxygen-candles-providing-emergency-air/

https://www.youtube.com/watch?v=g3Ud6mHdhlQ

Unfortunately they are "boring" in comparison, no flame/glow

https://www.amazon.com/Visibility-Eco-Friendly-15-Minute-Saf...

>Specified and approved by the Bureau of Explosives and Underwriters Laboratories. No expiration date on road flares, the date shown on the flare is manufactured date. Orion flares will burn in all weather conditions, waxed Flare w/Plastic Cap. 15 Minute Burn Time — Non Perchlorate Formula

I've always wanted to activate a road flare. It looks so cool when they do it on TV and the movies.

Amazon and your local auto parts store both sell them, they’re not expensive, so what’s holding you back? Just remember that they burn for 20 minutes or so, and you can’t extinguish them. (Well, a bucket of sand works.)

To be honest, I would be slightly nervous about getting into trouble with the law.

For what? What are you planning on doing with a lit road flare that would get you in trouble?

I thought it would be equivalent to calling in a "fake" emergency, or abusing the 911 system, or something like that.

Only if you do it in a place you’d otherwise not be able to have a fire. I wouldn’t recommend your living room, or the stairwell of you apartment complex.

Even 911 will reasonably accommodate a test call as long as it's not high usage period or whatever, call the non emergency line to coordinate if you're concerned, just say "I wanted to test e911 from my cell phone" or equivalent. Remember, systems need to be tested and testable in real life, not just software engineering! When you set up a PBX or voip phone system, you'd better make sure 911 works through it or someone might have a really bad day.

So what happens when they are put into a bucket of water?

Answered my question: https://www.youtube.com/watch?v=SldmXuV3cLI

There’s a reason that I specified sand in your bucket. :-)

I'm missing some context here: Why do we want to extract strontium nitrate anyway?

The author's home page reveals that he has an interest in amateur rocketry. Strontium nitrate doesn't sound suitable as a propellant, so I suppose he wants it to generate visual effects.

https://spiegl.org/unsorted/unsorted.html

Red rocket engine flame looks really neat.

Because we don’t have a Sigma Aldrich account.

And more importantly we don't want to pay.. $360 a kilo for reagent grade. Yikes.

Um... some context? What even are road flares? And why would I want to extract strontium nitrate from them?

(Road) flares aka. "pyros" are like fireworks that stay in place and give off bright light and heat. Their intended use is to warn others of accidents, or for a ship in distress, to help a coast guard helicopter find it. As safety devices, they're not hard to get in some countries/states.

Extracting strontium nitrate lets you .. build explosives from readily available materials? Or it would except, as the page shows, you need a pretty good chemistry set and knowledge to do this, at which point you probably don't need pyros.

I don't know if it's just a Europe thing, but pyros are illegally used a lot at soccer (EU: football) matches and other sporting events. Picture on this page: https://scottishfsa.org/pyros-burn-young-dundee-fan/

I'm from Germany, and I have never once seen a road flare used on an actual road. Not sure if they're even legal in the EU (sounds like a bad idea to carry explosive or highly combustible stuff around in your car?), here in Germany all you as the driver have to do to secure an accident site is set up a reflective "warning triangle" at a specified distance and wear a safety vest when outside the car. I have seen plenty of pyros at football matches, although I'm not sure those are being sold as "road flares".

You can however buy 'distress flares' in most of Europe, since many seagoing craft are recommended or indeed required to have the nasty, dangerous things.

They're not typically used for passenger cars, but semi truck drivers and first responders use them since they're visible from farther away in both regular and low visibility situations like fog, rain, and at night.

They are not used in europe. The first time I saw one was in Japan last week.

We have portable triangle reflector in Europe that are in every truck or car.

Consumer vehicle emergency kits used to come with them decades ago. Now they come with plastic reflectors or LED beacons.

They are mandatory on boats, even for smaller ones, and that's how you can get some in Europe.

I see them on roads all the time in Canada (Tow truck operators and law enforcement use them quite a lot). That being said, most vehicles on the road carry a large tank of highly combustible stuff which is a lot more volatile (e.g: Gasoline)

How does your car move around _without_ containing explosive, highly combustible stuff?

Yeah, but that stuff is in a hermetically closed, impact-resistant container, and the flares are probably not...

Flares will burn, and keep burning, once lit. I wouldn't consider them to be especially spicy in the whole context though, since anything that has set them off has already lit the rest on fire.

Coincidentally, I'm a volunteer firefighter, and helped put out a fully-involved car fire yesterday. The interior was GONE, except for seat springs and the like. Fuel too, of course, and the tires. The alloy wheels were more interesting, guessing there was magnesium sparking off in great showers of brilliant white. We're concerned around things like gas shocks and bumper / hatch struts, because they will pop off with some violence; we found a hatch strut yesterday, probably 20' _behind_ our truck after we were done. If there had been road flares in the mix, I'd be thinking, "oh, that's pretty".

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