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-------- Original Message -------- Subject: RE: Desperation Rebreather - shovel and all Date: Sun, 2 Mar 2003 17:10:07 -0500 From: "George Irvine" <trey@my*.ne*> To: "Don Burke" <donburke56@ne*.ne*>, "Quest@Gu*. Com" <quest@gu*.co*> Excellent - now forward it to techdiver and let the idiots debate it. If it gets beyond the calling me a "nazi" phase, I will jump in myself. -----Original Message----- From: Don Burke [mailto:donburke56@ne*.ne*] Sent: Sunday, March 02, 2003 5:07 PM To: George Irvine Subject: Re: Desperation Rebreather - shovel and all George, I think this is what you are looking for. ----- Original Message ----- From: "George Irvine" To: "Quest@Gu*. Com" Sent: 15 August, 2002 15:33 Subject: Desperation Rebreather - shovel and all > > Since those who do not know want to make an issue of me not being willing to > waste my time talking about why elephants can't fly, I will waste all of > your time with this one to get at those who keep recommending the Buddy > Inspiration, and who apparently have an agenda with this thing and other > shade tree rebreathers out there. > > Besides all the failure modes common to all rebreathers, like if the > mushrooms in the mouthpiece malfunction and take the diver hypercapnic or > hypoxic right away, or a loop hose failure, etc, the Desperation has its own > plethora of problems idiosyncratic to the unit. Other units have many of the > same issues, and almost all of the civilian rebreathers are poor excuses for > anything other than assisted suicide devices. In fact, most are merely > copies of each others bad ideas, and most are poorly funded , poorly > capitalized, poorly tested and otherwise poorly conceived wet dreams. The > Halcyon is a clever device, made more clever by Reinhard Buchaly, but is > still a dangerous piece of "kit", whereas the Buddy is a dangerous piece of > "shit". > > I will talk about the Inspiration Rebreather as it comes from the factory. > There are many ways to modify the rebreather as one may observe on the Star > Wars Bar Scene lists like "rebreather@nw*.co*" and is a complete topic > onto itself. I will stick to > the basics here and leave the "fix it at home" mods to the die hards on the > other lists. > > There is a small metal screw inside the oxygen sensor compartment, it is > located directly across from sensor number two. Condensation often forms on > this metal screw and will allow droplets to fall onto the oxygen sensors. > This will happen particularly if the diver moves from side to side as in > dumping gas from a drysuit or if they invert from horizontal for any > reason. > > Condensation is inherently found within this area and will form on the > oxygen sensors even without this metal catalyst. The O2 sensors are located > on the inhalation side of the breathing loop, so you have warm gas that > just > went through the scrubbing process meeting with cooler gas that you will > inhale thus the condensation forming on the cell faces. This condensation > causes discrepancies/inaccuracies within the cell readings and they begin > to > VOTE trying to figure out which one is more than .2 bar out of line with > the > other. Cell warnings will manifest within this period of time and the diver > will begin to get audible and visual alarms ...task loading increases. > > The unit alarms if it senses a PO2 over 1.6, which is a good thing. Problem > with this is that many of the divers will run 100% oxygen at 20 ft which is > a PO2 of 1.6, if they drop below the 20 ft they get an alarm, fair enough. > If you have several Inspiration divers in close proximity with cell warning > alarms, and high PO2 alarms it becomes very difficult to know if the alarm > is coming from your unit or from another diver. Some will be able to > assimilate this to being in an area where several cellular phones begin to > ring and everyone pulls out their phone to see if it was theirs. Mix this > with CCR divers using wrist computers that alarm and you really have an > orchestra playing down there, so much for the peace and tranquility of "no > bubbles". > > > Weight must be placed on the top of the rebreather in order to balance the > trim. If divers put to much gas in the counter lungs the upper body is > lifted and trim is then off center. Gas in a counter lung is just another > source to administrate, along with drysuit, BCD, PO2 on handsets, pressure > in O2 and DIL cylinders. > > > Many divers use the Inspiration to extend their times in open ocean, this > in > itself may pose problems. If the decompression gained by the increased > bottom times is met with undesirable conditions such as rough seas it is > not > so easy to adjust buoyancy as with breathing open circuit. Many of the > buoyancy characteristics involved with rebreathers require a longer > learning > curve and must be anticipated, if the diver is not up to par they are much > less forgiving than OC. If the constant PO2 is increased or decreased too > quickly due to unforeseen circumstances the diver could quickly become > hypoxic/hyperoxic. > > > Mouthpiece does not have OC bailout built into it, bailout is a time of > increased stress so it is pertinent the transition should be smooth without > chance for a mistake. The bailout procedure on the factory unit uses a > device called an Auto Air, this duals as a breathing device and BCD > inflator. I couldn't imagine this being an effective tool for gas sharing, > nor proper bail out for the user either, as the CCR mouthpiece has to be > effectively closed before the transition to OC bailout is performed or it > will flood the breathing loop making the diver negatively buoyant. Bail out > should be in the form of a combination unit on the mouthpiece to facilitate > safe transition. > > If the O-ring on top of the cartridge lid is dirty or not aligned properly > CO2 will take the path of least resistance and bypass the carbon dioxide > scrubber therefore breathed back into the loop. Hypercapnia begins and the > diver is faced with another problem to solve. > > As the diver descends they must equalize the counter lungs, if this > procedure is not adhered to and they begin an uncontrolled descent the > lungs > collapse and the diver is not able to breath, an automatic diluent add is > an > aftermarket product which does combat this. But since we are talking > factory > here the diver is faced with equalizing counter lungs, ears, sinuses, mask > drysuit, BCD, monitoring PO2 on handsets, buddy position, light and depth > in > the water column. It has been mentioned before that this is "a busy time". > > Inspiration does not have SS backplate and utilizes many plastic fastex > clips, which some view as failure points. There are seven quick releases on > the soft harness including the crotch strap and handset clips. The clips > that hold the yellow casing lid on the unit break frequently so spares are > required as well. > > > Often difficult to transport with Sofnolime, if you do not have an MSDS on > your person you will be declined, even if you do have the Material Safety > Data Sheet on hand and the handler does not feel comfortable with the issue > they will not let the scrubber material on the plane. Most Inspiration > divers seek out "Inspiration friendly dive Centers" so they are able to > obtain the wide array of parts required to service and maintain. > > The oxygen sensors are proprietary to the Inspiration which limits the > diversity on this product. Many of the CCR's will allow various types of > sensors to be used but not so the case with Inspiration's and it is > strongly > voiced by Martin Parker. Patrick Duffy with Oxycheq in the US sells similar > sensors and says there is absolutely no difference between the Teledyne's > he > sells and the Inspiration sensors. > > Scrubber canister is small (2.45 Kg of 8-12 mesh, 797 diving grade > sofnolime) and does not facilitate the use many of the mixed gas > Inspiration divers put it through. At depth CO2 breakthrough is rapid even > with a resting diver, if breathing resistance is elevated the scrubber is > near void. With increased CO2 build up the diver is of course exposing > oneself to further malady. Diving high helium concentrations assist with > this problem as it is less dense than air, easier to breath therefore less > CO2 buildup and the scrubber should last longer but it is playing on the > edge. High PPN2 should be ultimately avoided. > > If counter lungs are not situated adequately they will float above the > divers shoulders and increase breathing resistance. It is taught in the > basic course to watch for this ... But they are clipped down with fastex > buckles which as we know do fail on occasion. With the diver already quite > task loaded on the CCR it is easy not to notice the lung has crept up, CO2 > will then increase from breathing resistance. > > The LP hoses which feed the diluent and the oxygen inlets on the counter > lungs use a different end than the BCD inflator. The BCD is inflated with > Diluent gas, the same which you are adding into the counter lung, there is > no sound reason not to have the same end on this for diversity. The reason > the end is different on the BCD inflator is to supply a greater amount of > gas to the Auto Air regulator used as a bailout/inflation device. This Auto > Air is prone to free flow situations and can dump the diluent gas if not > tended to quick enough. Most Inspirations divers discard this Auto Air > early > into their CCR career. > > If both handsets shut off in the water the diver is faced with a series of > questions in order to "reboot" the system. One of the questions ask if you > would like to calibrate "yes or no" if the diver is stressed and chooses > "yes" they will effectively be adding 100% oxygen into the breathing loop > no > matter what depth they are at in the water column. > > If the battery is low it will not supply enough EMF for the oxygen solenoid > to open the valve and add life sustaining gas. > > The control handsets are secured to the canister via rubber hose, the > wiring > is run through this conduit down to the electronic handsets that are > monitoring the dynamics of the oxygen sensors. These rubber conduits enter > into the scrubber/O2 sensor compartment where it is humid and if not > perfectly sealed will allow condensation to migrate into the hose and wreak > havoc with the electronics in the handsets. Many electronic problems with > the handsets have involved this scenario. > > See Mike Pizzios complaints on techdiver, see the archives of techdiver for > info on the Dsperation, see the UK coroner for what the bottom line on this > thing is. My take? "needs to be sold with a shovel". > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: quest-unsubscribe@gu*.co* > For additional commands, e-mail: quest-help@gu*.co* > > --------------------------------------------------------------------- To unsubscribe, e-mail: quest-unsubscribe@gu*.co* For additional commands, e-mail: quest-help@gu*.co* -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. 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