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Re: 2 liter bottle launcher safety

At 12:16 PM -0500 2/11/01, Dave Wiener, you wrote about 2 liter
bottle launcher safety:


What is the maximum pressure you allow your students to use when using
compressed air to launch a 2 liter bottle? What maximum compressed air
pressure can one of these bottles take? Our launcher is homemade, should we
expect the O-ring seal to limit the maximum pressure? If the bottle were to
explode will it just split open or will flying fragments be produced? Any
warnings, recommendations, and/or precautions would be greatly appreciated.

A 'fresh' bottle will easily withstand 200 psi. As they get 'crumped'
they will weaken.

Scuba tanks are tested with water pressure so that if one DOES
rupture, the low compressibility of water will limit the destructive
shrapnel.

Similar results would apply to your bottle 2/3 full of water. The
neck-piece could do the most damage because of its greater
mass/surface ratio. But the neck is probably fairly well restrained
by your launcher latch???

We usually limit ourselves to about 60 psi - just because that's what
the cheap pumps can put out easily.

I stress the safety issue and try to be overly cautious. (Pretending
that ~ 100 psi will cause a TERRIBLY catastrophic explosion, etc.)

These bottles can withstand the critical pressure of CO2 + lots more
before exploding!!!!

Solid CO2 will be totally absent during the final contortions of the plastic.

(I've destroyed one of our chemistry folks blast shields, but it was
cracked to begin with and NEEDED to be discarded. The lamination in
the glass DID hold the shards effectively!)

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