[PSUBS-MAILIST] buoyancy

[Alan via Personal_Submersibles]

Hank,
in general, from memory, the fibreglass products I put through my
pressure program, had similar external pressure resistance to the internal.
However the carbon fibre had better tensile strength than compressive strength.
If your tanks are rated to 3,600psi they probably have a 4  x safety factor ( you could 
check that), so may crush at 14000 psi or 28,000ft. 
looks like a big safety margin. I am putting in a positive comment here but
obviously that would need verifying.
Cheers Alan

Sent from my iPad

> On 12/11/2015, at 2:33 am, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> I was thinking about using CNG (compressed natural gas)  tanks for buoyancy.  The type 4 tanks are carbon fibre and rated for 3,600 psi and very light.  My idea was to keep the tanks full of compressed air so they can withstand the sub depth rating plus a safety margin.   I am liking trawl floats may be better now because they are rated high enough and not air filled.  The CNG  tanks are much cheaper and conveniently shaped.   Hmmm not sure now.??
> Any thoughts or concerns anyone????
> Hank
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