<html><head></head><body><p dir="ltr">If any pressure vessel inside the personnel compartment (or its associated piping / fittings downstream of a hull shutoff valve) were to fail and release its contents into the compartment, it must not raise the internal pressure of the compartment by more than 1 ATM (demonstrated by calculations). If it does, it must go outside, no exceptions.</p>
<p dir="ltr">Also, technically you're supposed to have two independent methods of emptying hard ballast tanks, so for example, pumping them out against the sea pressure with a high pressure pump (powered or manual) and simultaneously venting 1 ATM air into the tank with a check valve as one method, and opening the tank to sea and blowing it out with HP air as the second method.</p>
<p dir="ltr">Sean</p>
<br><br><div class="gmail_quote">On December 7, 2016 4:59:02 PM MST, Brian Cox 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="font-family:Arial, sans-serif; font-size:10pt;"><div>I'm routing my lines to use two scuba tanks as my internal ballast. I estimate the total weight if they are both filled with water to be around 42 lbs. (about 570 cu in for each, alum 80's) . What kind of water line does everybody use? I was considering using soft copper but I'm not sure of it's pressure rating. Or maybe that is not such an issue. It could see some pressure using the HP tanks in a closed position, which then could be an issue I guess. But I would most likely just give a little blast of HP air to push the water out. Hmmm, wonder if I should have the option to vent outside the sub if I had some air pressure in the ballast tanks? or I guess I could just simply let it push all the water out and then it would get expelled that way. Are there any specific rules like that for inside ballast
tanks?</div><div> </div><div>Brian</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>