Hi Alec, That is interesting that you don’t use O2 for short dives. What O2 percentage level do you consider it is OK down to? I guess that if you have 1 cubic meter of free air space it would take 1.8 hours at ABS .47 litres / minute to reduce to 15% and that would be 850 mbars then you could add a bit of air which would then bring it up to about 17% providing of course that you are scrubbing. Saves on costs. What are the negatives if you are only doing 1-1.5 hours at a time. Does anyone else do this? What is the medical O2 regulator brand you are using? Regards, Hugh From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Smyth, Alec Hi Hugh, It's a little of a tangent, but I've just got rid of the air regulators altogether. I stole the idea from Greg Cottrell, on the basis that the fewer moving parts is best. I simply pipe in HP air with Swagelok tubing and regulate the MBT blows with needle valves. Of course there's still hull stops, and a cross-over valve allowing you to supply the blow line for both tanks from either bottle, but it is certainly a simpler setup. For O2, the regulator should ideally go outside as low pressure O2 is far less likely to ignite than HP, and if an O2 fire is to occur, it would be rather nicer to leave it on the outside. I can't recall what brand my O2 regulator is, it's just a SCUBA 1st stage cleaned for use with 100% O2. The 1st stage feeds a little medical O2 metered regulator that's inside. I'm sure there are much more sophisticated solutions, and must admit I've never even turned on my O2 system because my dives are too short to need it, but I expect that to change next time out since Snoopy is now a 2 person boat. Thanks,
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Hugh Fulton Placement of regulators and choice of them. For Air and oxygen. Is it best to have the regulators inside or outside the pressure hull? I noticed that some have the regs outside and others inside. What brand/models have people found the best? Hugh
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