Hey Dave!

jaap · 29th June 2006, 15:40

About your cryo-SCUBA, are you sure its intended for liquid air while in use?

Many of those cryo breathing systems use supercritical fluids to avoid the problem of sliding gasfractions (we had an email discussion a few years ago about it). The SCAMP by NASA and some old Interspiro projects for example.

If the dewars in the cryo-SCUBA are pressure resistant one way of doing it could be to partially fill the dewar with liquid gas that is breathable and then seal it and let it build pressure (I don't know if they do it exactly that way). This would increase the pressure and raise the temp so that the dewar would hold supercritical fluid near its point of liquifaction (neither liquid nor gas). Taking your breathing gas from this fluid would not alter the gas fraction during the dive.

About the minium front Rebreather, did you do anything with the IDA-76? I really enjoy my slightly modified IDA-76 for O2-Rebreather dives. When I get some more time I will definately turn it into a mixed gas CCR.

Nice to see you here, this really turns on my Rebreather-rebuilding fetish...

**Dave Sutton** · 30th June 2006, 10:19

The Dewers are definately pressure resistant, welded stainless steel pressure vessels. So you're probably right on the method of use. At one time there was a system drawing of the Kriolang on the web, I searched for it last night and came up empty. The descrtiption then said that there was a "dive" andf "predive" setting on the valve, and te diver would open the valve to "predive" and then wait 15 or so minutes for the cycle to start and then begin diving. This make sense to you?

IDA-76 is a fun little rig, I assume you replaced the bottle array with a standard small bottle? Toss a photo here, or I'll show one when I get back.

Off diving.... back in a week-ish. Might be able to check mail during the trip though but not sure.

Dave

jaap · 3rd July 2006, 11:24

Hmm, is there some form of intermediate pressure resevoir in the rig? I have no idea but it should make sense that the predive mode allows an intermediate resevoir to fill with gas coming from the pressurized dewars.
When the unit is dived this intermediate resevoir would function like any other pressure tank giving the diver gas?

"IDA-76 is a fun little rig, I assume you replaced the bottle array with a standard small bottle? Toss a photo here, or I'll show one when I get back."

I have an adapter to fill the array so I can dive it. But they are rather small, total gas ~0,45l@150bar. So if I use it like that I have another O2 source with me for predive flushing to save on the array.

Or like in the photo, Replaced the OPV with a drysuit valve and bring say a 1,5l alu tank with O2 (The bottle is on the side of my backplate). Also added some soft leadbags under the CL to improve the trim.

The photo is a few years old and I have since added a feed on the LP line from the array to the ADV so that any gas can be plugged in on it.
So the OPV is back again. I also attacked the DSV and recut it to accept a small secondstage making it an OC/CC DSV, but it didn't turn out great.

So when I get around to it I will add a Dräger DSV to it and a P-port or two and use it etiher as a CMF-SCR or a small MCCR. Only trouble is I have too damn many Rebreather waiting to get modified...

29th June 2006, 15:40	#41 (permalink)
jaap Normal people worry me Current Rebreather/s: Classic Kiss Other CCR RB80 / Clone Ray Other SCR Home Build Other Rebreather/s: Other CCR RB80 / Clone Ray Other SCR Home Build Join Date: Jun 2005 Location: Stockholm Sweden Posts: 473	Re: Hey Dave! About your cryo-SCUBA, are you sure its intended for liquid air while in use? Many of those cryo breathing systems use supercritical fluids to avoid the problem of sliding gasfractions (we had an email discussion a few years ago about it). The SCAMP by NASA and some old Interspiro projects for example. If the dewars in the cryo-SCUBA are pressure resistant one way of doing it could be to partially fill the dewar with liquid gas that is breathable and then seal it and let it build pressure (I don't know if they do it exactly that way). This would increase the pressure and raise the temp so that the dewar would hold supercritical fluid near its point of liquifaction (neither liquid nor gas). Taking your breathing gas from this fluid would not alter the gas fraction during the dive. About the minium front Rebreather, did you do anything with the IDA-76? I really enjoy my slightly modified IDA-76 for O2-Rebreather dives. When I get some more time I will definately turn it into a mixed gas CCR. Nice to see you here, this really turns on my Rebreather-rebuilding fetish...
(Offline)

30th June 2006, 10:19	#42 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: Hey Dave! The Dewers are definately pressure resistant, welded stainless steel pressure vessels. So you're probably right on the method of use. At one time there was a system drawing of the Kriolang on the web, I searched for it last night and came up empty. The descrtiption then said that there was a "dive" andf "predive" setting on the valve, and te diver would open the valve to "predive" and then wait 15 or so minutes for the cycle to start and then begin diving. This make sense to you? IDA-76 is a fun little rig, I assume you replaced the bottle array with a standard small bottle? Toss a photo here, or I'll show one when I get back. Off diving.... back in a week-ish. Might be able to check mail during the trip though but not sure. Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
(Offline)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode