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Barrie, In reply to: On Thu, 30 May 1996, Barrie Kovish wrote: > However it might be possible to use the breathing parameter to verify > that the constant mass flow valve (CMFV) is operating correctly. If it > is then the breathing rameter should remain constant. If the > breathing parameter is not at is expected then there is some problem > with the CMFV and you may be danger of becoming hypoxic. > I have heard of at least 2 cases of divers deaths due to plugged CMFVs. The Atlantis I uses a laser bored synthentic semi-precious stone and requires a closed test on the surface to ensure that the system fills. The only available orifice in the US is the 7.5 liter one. The pressure on the orifice is high: it's a 4.0 liter 200 bar cylinder. As the mass equation requires, assuming the cylinder pressure to be at least twice ambient, the gas to travel at the speed of sound, the only variable is the area of the orifice. If x minutes go by and you note that the SPG has not dropped by x times 2bar, then the orifice must be blocked. I think you've just added rule 12 to the physiologic safety parameters - the diver must check/time the fall in pressure of the SPG. The Aladdin/Nemesis Nitrox doesn't display your breathing parameter under water, so it's not going to be of more use than the SPG. -ph
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