Will a spray can of chemical mace explode in a hot car? If not, why not?
If it’s a pressurised container, it is subject to the same reason that any type of can like that should not be heated. The explosion is a function of pressure rather than the actual chemical content of the container, so a tank of helium could explode in much the same way if the internal pressure exceeds the strength of the tank.
If the can of mace heats up beyond a certain point, the internal gas pressure will eventually exceed the limits of the metal can and it will break open, often explosively.
It may be that the contents just don’t have the ability to raise the pressure inside when heated, until you start getting to temperatures that would require an active heat source like a fire rather than just passive heat in a closed car. In this case, unless the can is damaged it will not explode in a hot car.
So you figure it would be safe?
I would appreciate any other Smart Person. I do not need a tear-gassed car.
Most aerosol containers say not to store at temperatures exceeding 120°F.
The usual safety warnings given for pressurised cans like hairspray, deodorant etc are 50C (122F). Temperatures in excess of this are considered unsafe. If the interior of your car exceeds these temps for a long period, I would not store a pressurised can in there. Your best bet is to check the thing itself.
If it does go, it’ll be quite a bang. Pressurised cans are quite energetic when restoring equilibrium. The term is BLEVE - Boiling Liquid Expanding Vapour Explosion, although the non-official backronym is “Blast Levels Everything Very Effectively”. Tank failures can be very violent.
Mythbusters to the rescue!
From here.
I had a can of fix a flat “explode” in my car. What a frickin mess. Sticky, rubbery shit all over everything.
As for mace, even if it just seriously leaks in a car things could get nasty. Mace is some strong shit. I’d store that stuff in the part of the car likely to be coolest (like down low, under the seat say). And in a container that would contain the liquid. Maybe a larger tupperware container with some paper towels to absorb any liquid.
Oh, and leaving car windows down enough that something can get in the car can be a problem too. Ever had a tom cat spray the inside of a car? Not good either.
I though Mace was considered obsolete and that everyone uses pepper spray now, but of course things might be different in Qatar.
I’ve thought about getting pepper spray, but this is why I haven’t. I don’t live in an area where I need to have it on me 24/7. I don’t want to have more stuff in my pocket all the time. I’ve thought about getting some to keep in my car so I could take it out and carry it when I want to, but I don’t want it to leak in the car. Cars can easily get over 120 F. I don’t know why they would design them to such a low temperature, as there must be people who leave them in cars. Is there anybody who sells pepper spray that can be left in a hot car?
Thank you all. I suppose I ought not to risk it.
Since aerosol cans became popular in the late 50s, how many thousands, nay, millions, of people have cans of something rattling around in their trunks? Cans of paint, cans of starting fluid, cans of windshield de-icer. Cans of fix-a-flat. Or cans of hair spray. Or WD-40. Or …
How many people living in hot climes have bought a can of whatever, then made three more stops before getting home? All the while the can’s sitting in the trunk or backseat.
And of all those people, how many have had something burst? My answer: not zero (see above) but not very many. Or else we’d have heard the the product liability hue and cry by now. And the actual max safe temp of the cans would be raised.
50C/120F is a nice round safe number for the can manufacturer’s lawyers to put on their labels. That doesn’t mean they burst at 51C/122F.
I consider *Mythbusters *to be an interesting source of anecdote; nothing more. But their results match the statistical reality we seem to see in the US desert southwest today. Or at least what I saw in my decade+ living there, as well as my wife’s 2+ decades there. Normally, cans don’t burst at temps found is sealed up cars in the desert. Defective cans might, and ones with leaky valves might leak more in teh hot than in the cool. But failures are long shots, not common ocurrences.
Now the Middle East may well have temps & solar flux to beat the heck out of AZ, NV, and NM. I don’t know. But my WAG is it isn’t worse enough to make the critical difference.
I believe those who say it is a rare event, but nothing is impossible. It is quite the surprise to have a can of Dr. Pepper rupture and take off from the cup holder bounce off the ceiling and spray the interior while traveling at speed on the highway. At the time it was an extraordinarily hot day and the can had only been there for a few hours, but I figured it was the combination of heat, being bounced around (carbonation) and a flaw in the can.
So I would give it a non-zero chance that it would happen.
You would sort of think these things would be police-car friendly.