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RE: [PSUBS-MAILIST] Regulators
Alec do you have emergency suba breathing device on board for each person - in case of a small fire?
vbr Carsten
"Smyth, Alec" <Alec.Smyth@compuware.com> schrieb:
> Hi Hugh,
>
> In his book, Kittredge describes how for many years he used the "SAR" method. It's a laugh because it sounds very high tech but means nothing more than "Surface And Replenish". This was the method he knew from Navy submarines in WWII. It is quite adequate for a K boat if you're making short dives. Typically we set the dive timer at 20 minutes, and the air doesn't feel stale for an hour and a half hours. I have to admit, although I've got an O2 meter on board I can't recall the reading after 20 minutes because it's an absolute non-issue.
>
> Snoopy also has a scrubber, an O2 regulator, and a barometer. No automation to the O2 injection, you would just adjust the flow rate every so often based on the evolution of cabin pressure. What I've done thus far is dive with a full tank of O2, the tank valve open, but the hull stop closed. The Sofnolyme is in a sealed plastic container, not loaded into the scrubber. If I did get caught up on something and couldn't surface, I'd have plenty of time to load the scrubber and turn on the O2, but I've never needed to. I do anticipate changing this SOP to using life support on two person dives. Not so much because I would need life support for a 20 minute dive, as much as because the boat is so cramped with two people that it would be much more of a hassle filling the scrubber!
>
> The medical regulator I've got is like eBay item 150464127173. Cheap little things. They come in a variety of flow rates, but the lower ones like 0-4 lpm would give you the best fine tuning. Search on "pediatric medical regulator", as "pediatric" will zero in on the ones with low flow rates. A person consumes roughly 1 lpm at rest, so there's no point in using a regulator that delivers 15 lpm, as you would lose out on adjustability.
>
> Snoopy's life support is decidedly elementary, but one nice innovation I'm working on now is an almost-off-the-shelf scrubber. More on that in a couple of weeks!
>
> Thanks,
>
> Alec
>
>
>
>
> ________________________________
>
> From: owner-personal_submersibles@psubs.org on behalf of Hugh Fulton
> Sent: Thu 12/30/2010 5:53 PM
> To: personal_submersibles@psubs.org
> Subject: RE: [PSUBS-MAILIST] Regulators
>
>
>
> 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
> Sent: Friday, 31 December 2010 9:16 a.m.
> To: personal_submersibles@psubs.org
> Subject: RE: [PSUBS-MAILIST] Regulators
>
>
>
> 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.
>
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> Thanks,
>
>
> Alec
>
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>
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>
> From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Hugh Fulton
> Sent: Thursday, December 30, 2010 2:53 PM
> To: personal_submersibles@psubs.org
> Subject: [PSUBS-MAILIST] Regulators
>
> 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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