[Zymergist]

WOW,

I personally am shocked that they would not fill the vented space with saline.

As a trained Tek diver and breathing gas blender I have studied a bit on diving physiology. Why they make the Nitrox distinction at 135 is beyond me as the recommended MOD (max Operating Depth) for Nitrox I (32% O2) is 111 ft (and for Nitrox II at 36% is 95ft, other mixes have differnt depths). Below that your PPO2 (partial Pressure of O2) is over 1.4 putting you at risk for O2 toxicity and CNS seizures. (lot more info on this topic, but this is the base recreational limit) These facts lead me to question what they actualy know about hyperbaric physiology.

The problem I see with the device being filled with air is that they have introduced an embolus in the spinal area. As you descend the gas will compress drawing fluid in to the space (hopefully with no blockage of the ports!). When you ascend the gas will expand pushing either fluid or gas back out depending on relative position of the port.

There is some documentation of pulmonary gas embolism combined with inert gas saturation well within no decompression limits (coughing at depth and ascending while coughing over pressurizing the aveoli in the lungs) causing type 2 DCS with no documented survival. Basically the free gas bubble acted as a nucleating event causing dissolved gas to come out of solution.

Sorry if I went a bit deep (no pun intended...) on the topic, but I am an info geek.

I personally question the safety of diving with this device unless the gas displacement can be verified. If you do dive I would stay VERY shallow (<30ft) and also not go over 30% of your bottom time. If you are Nitrox certified and it is available this would add a safety margin (But I would still use air calcs) This thought is strictly related to any gas in the M-6. Any fluid in the M-6 should not really be exposed to gas absorption (except the gas in the device) as there is not realy circulation. If there is no gas in the device there will be little to no fluid movemend and the only gas absorption would be cell to cell through the vents. For comercial saturation diving this would be a problem, but not recreational.

As it is past the trip date how did it go and did you dive?