That’s a crappy pressure vessel holding 350ml of 80psi air, for about 100J of stored energy. I’m not entirely sure I’d be comfortable with that, especially anywhere with my face in the line of fire it it fails.
replyYour bike already has two crappy 80psi pressure vessels, why not three?
replyThose two pressure vessels are highly engineered and are wrapped with materials with pretty good tensile strength. Also, they’re made out of materials (fabric and rubber) that absorb a decent amount of energy when they tear and that don’t fragment. And the whole assembly usually depressurizes slowly.
replyHaving personally blown up beverage bottles by overpressurizing them (be very very careful doing this!), when they go, they go violently.
I've blown up beverage bottles for fun. Hooking an air compressor to a 2L bottle and exploding it makes a satisfyingly loud boom.
reply*We had a valve on the air line so we could be at a safe distance when pressurizing. Be very careful. It's unpredictable exactly at which point they'll blow. Sometimes they hold full pressure for a couple seconds and then go.*
i like to use dry ice for pressure, make sure you have a gun to shoot it if it doesn't go off
replyIt's a soda bottle - it fits in your water bottle holder, and you can replace it for a couple of bucks if it fails. 80 psi is pretty low pressure (typical narrow tires are 100-120) and the bottle itself is very low mass, so the fabric around the bottle should ensure safety if it bursts.
replyIIRC these came out in the early-mid 90s; a bike messenger trick at the time was to fasten the horn to your handlebars with velcro, so you could take it off and hold it near a car window when triggering it.
I suppose I should maybe not worry about 80 psi so much. An ordinary bottle of soda on a moderately warm day is around 80psi. The energy is 1/2 * pressure * head space (roughly), and head space is minimal. But you can chill it in the fridge, then open it and quickly pour out half, then close it and let it warm up, and you may still be near 80 psi, and I’ve never heard of anyone getting maimed by an exploding soda bottle.
replyIf it fails by blowing the end off toward your face what damage will it do?
reply> That’s a crappy pressure vessel
replyThat's a huge assumption, and likely incorrect.
Good point, but I abused it pretty well and it seemed to do OK - was also in a water bottle holder so closer to the legs than anything.
reply> When I was commuting 60k/day on my bike in shitty suburban conditions
replyHere I thought my 4.5 mile (7.25 km) bike commute was a bit long...
An hour and a bit each way, took about as much time as public transit and better than a coffee for waking up. A good road bike goes a long way, and the suburbs suck for road sharing but are great for not having to stop at many lights.
replyThe winters were rough though.
Can confirm, AirZound is great!
replyYeah I had something like this for several years. Works really well for cars
replyI wonder if one of those recently-emerging Chinese electric blowers that sub for canned air would generate enough air volume to sound the horn usefully. Possibly not quickly enough.
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