aren't most dive components steel based instead of aluminum? i understand
that the life expectancy of the steel products is a lot longer. aluminum has
a tendancy to stress crack. hence the mandatory tank inspections, and primary
reg rebuilds etc.

how thick is the wall on your dive tanks?
i don't know exactly what kind of aluminum alloy they use when not steel.

moose.
(i don't dive myself... lots of perfectly good air on the surface, but i have
buddies who teach and do cave diving.....  http://www.abletodive.com  so i
absorb lots through my skin )


On March  4, 2002 08:11 pm, you wrote:
> Any physics people lurking?
> This is PIC related, because solving the problem will give me what I need
> to attach a PIC to for my latest hobby project.
> I am working on an addition to my home-made SCUBA gear. I want to make a
> sensor that I can screw in to a hig pressure port on my 1st stage regulator
> that will output an analog or digital output that is proportional to the
> pressure inside the tank. It would be even better to convert that to
> volume, but that's not the issue here.
>
> The tank is normally filled to 3,000 psi. My idea is to make a small
> secondary cylinder approximately 1 inch long with a 1/8 inch bore. I
> envision a piston with a compression spring with 38 lbs of force to cover
> the range from 0 to 3,000 psi.
>
> Assuming the cylinder I make is to be aluminum,
> how would I figure the minimum wall thickness needed for 3,000 psi?
> I assumed that figuring the bulk modulus of aluminum at 7 * 10^10 in N/sq
> cm for the area of the inside cylinder wall surface would do, but the
> result does not seem reasonable.
>
> This is proving to be a tough one for a mid 70's EE major turned business
> major turned PCE, turned IE, turned JOAT to figure out.
> I have read that mechanical failure of such a vessel is analogous to a
> small hand-grenade accident (if there is such a thing!)
> Can anyone help me prevent a potentially catastrophic test of my first
> prototype? After all, hobbies are supposed to be for fun and relaxation,
> not hospitals, right?
>
> Chris.
>
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