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.

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gibspaulding 3 hours ago | parent | next [-]

Your bike already has two crappy 80psi pressure vessels, why not three?

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amluto 3 hours ago | parent [-]

Those 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.

Having personally blown up beverage bottles by overpressurizing them (be very very careful doing this!), when they go, they go violently.

	▲	BenjiWiebe an hour ago \| parent [-]
		I've blown up beverage bottles for fun. Hooking an air compressor to a 2L bottle and exploding it makes a satisfyingly loud boom. 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.

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stronglikedan 4 hours ago | parent | prev | next [-]

> That’s a crappy pressure vessel

That's a huge assumption, and likely incorrect.

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pjdesno an hour ago | parent | prev | next [-]

It'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.

IIRC 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.

	▲	hdgvhicv 26 minutes ago \| parent [-]
		If it fails by blowing the end off toward your face what damage will it do?

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srejk 4 hours ago | parent | prev [-]

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.