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In message <Pine.SOL.3.92.960530113123.2428G-100000@hs*.us*.ed*>, "Peter N.R. Heseltine" <heseltin@hs*.us*.ed*> writes >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 other orifices are now being shipped in the UK. > 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 Regards Chris Chris Hellas e-mail:- chris@de*.de*.co*.uk* ********************************************************************************
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