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Brent, All of this should be quite calculable, rate of expansion, pressure increases, venting rate required to remain within parameters, valve capacity...etc. If one is truly serious regarding building an ambient, then the best bet is to copy what others have done, IVC, Exomos, Carib,...etc. The trouble that I found with them is that they are good at giving up sales data and pretty mum about technical details. You would have to pose as an interested party and ask the pertinent questions prior to them getting wise and shutting down on you but, you could get the buoyancy control details from them this way because you are so "concerned" safety wise! :) Joe From: brenthartwig@hotmail.com To: personal_submersibles@psubs.org Subject: RE: [PSUBS-MAILIST] Venting an Ambient Date: Thu, 4 Sep 2008 21:36:48 -0700 I forgot to add that, if I need to blow air into the inflatable pontoons to surface, that I can add just enough air to make the sub start to ascend, much like some PSUBBERS do with there MBT's. That way as I rise, the air will fill the pontoons, hopefully slower, and also keep my sub from accelerating as fast in a dangerous manor, and put less pressure on the interior surfaces as the air expands and tries to get out of the expansion valves. If I'm really deep then I'll need a better valve design to deal with the faster changing pressures inside the pontoons when they get totally full and the sub starts to accelerate. But I still expect to need a number of expansion valves regardless. I would hate to have the pontoons pop when ascending, it they are my last option for lift. Your expanding air filled dreamer ;)' Regards, Szybowski From: brenthartwig@hotmail.com To: personal_submersibles@psubs.org Subject: RE: [PSUBS-MAILIST] Venting an Ambient Date: Thu, 4 Sep 2008 16:13:52 -0700 Hi Joe, This point you made below, is exactly what I want to figure out for my inflatable pontoons, so I can blow them at depth if I need to in an emergency. Most of the time I would only fill them up when I get back to the surface. "What would a cracking pressure of 0.5 to 2 lbs translate to in hull overpressure, and how many would be required to dump expansion in an emergency ascent from max depth." Your resident pontoon dreamer ;)' Regards, Szybowski From: joeperkel@hotmail.com To: personal_submersibles@psubs.org Subject: [PSUBS-MAILIST] Venting an Ambient Date: Thu, 4 Sep 2008 13:59:49 +0000 Someone asked about venting an ambient. I found some PVC check valves today which could quite possibly do the trick but I think you would have to ask two questions. What would a cracking pressure of 0.5 to 2 lbs translate to in hull overpressure, and how many would be required to dump expansion in an emergency ascent from max depth. Otherwise, these look pretty nifty! Joe |