<html><head></head><body><p dir="ltr">Fiber composites are not isotropic and do not lend themselves well to analysis for externally pressurized applications in the absence of destructive testing for verification. I presume you mean to employ these as hard / variable buoyancy tanks? With the active pressure compensation, you need to consider the consequences of a failure in the compensation system. An imploded buoyancy tank could have severe consequences. If looking for permanent buoyancy, syntactic foam is highly unlikely to fail unexpectedly.</p>
<p dir="ltr">Sean<br>
</p>
<br><br><div class="gmail_quote">On November 11, 2015 6:33:46 AM MST, hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px"><div id="yui_3_16_0_1_1447248265971_2399" dir="ltr">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.??</div><div id="yui_3_16_0_1_1447248265971_2399" dir="ltr">Any thoughts or concerns anyone????</div><div id="yui_3_16_0_1_1447248265971_2399" dir="ltr">Hank</div></div><p style="margin-top: 2.5em; margin-bottom: 1em; border-bottom: 1px solid #000"></p><pre class="k9mail"><hr /><br />Personal_Submersibles
mailing list<br />Personal_Submersibles@psubs.org<br /><a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br /></pre></blockquote></div></body></html>