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I see where they have put some lipstick on the Inspiration and are trying to sell it to the military. Have the issues outlined below been corrected? It's one thing for someone with a few grand burning a hole in his pocket to kill himself. It's quite another to order someone's kid to use something like this. I used to get a funny feeling in the pit of my stomach when I saw guys dress out in MK15/MK16 gear. This would be many times worse. ----- Original Message ----- From: "George Irvine" <girvine@be*.ne*> To: "Quest@Gu*. Com" <quest@gu*.co*> 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". -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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