SWK is correct. Oxygen piped from the hospital walls or from medical cylinders is definitely _physiologically_ dry. Should humidified oxygen be required there are various (and some interesting) methods of humidifying this before it reaches the patient's airways. Where the natural filtration/humidification processes of the nasal passages and mouth are bypassed, this then becomes very important.
So the 67 ppm as outlined below is dry by my frame of reference, but this may well become significant at near or sub zero temperatures. How significant, I am unsure. My patients and I luckily do not get to 14000ft. We operate at 21 (room temp) - 43 degrees (air temp at humidifier before traveling down inspiratory limb of "breathing circuit") at 1200ft QNH (Toowoomba) (But interestingly high enough to be considered a "flight" after a day's diving at the coast!) I imagine the patient's and pilots oxygen in the situation below would be fine in a pressurized/ temp controlled cabin, but the pilots emergency oxygen (from what I understand) is supposed to supply a higher inspired fraction of oxygen when the cabin depressurises due to malfunction. And then if the temperature drops, will the equipment freeze? (I dont even want to consider the patient ;)) I do not know the answer. I suppose the question is: (using BOC's criteria for definitions): Is the 67 ppm moisture in medical O2 dry enough for oxygen delivery equipment in the glider cockpit environment at high altitude and low temperature (with all things being equal with regard to clean cylinders with no air mix) Or does it have to be the < 7ppm DRY breathing O2 to be safe (with regards to equipment function)? I'm in Namibia, luckily far from my trusty ADSL connection to go google that question (or be forced to consult aero medical journals) Food for thought... Merry Christmas A.J. (Could I live in a country where ADSL is not available?) SWK wrote: I am sure that the doctors on this group can give the yay or nay, but I was lead to believe that in medical use a humidifier is used between the bottle and the patient. As for the difference between medical and dry breathing oxygen, I was speaking some years ago to the LAME who looks after some of the RFDS aircraft. He would top up both the pilots emergency system and the patients medical system from the one bottle. I seem to recall he used medical oxygen for both with no ill effects (either in practice or in auditing!) Regards SWK Just had a quick look at BOC medical gases. Oxygen impurities: medical - moisture < 67 ppm (seems pretty dry to me, as far as patients breathing it goes) dry breathing - moisture < 7 ppm (and strangely New Zealand oxygen < 15ppm) https://pgw100.portal.gases.boc.com/scripts/wgate/zcpwp_b2c/!?~login=boccoma u (then products/medical/medical gasses/oxygen) ________________________________________ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of PTB My understanding is that medical O2 is specifically supposed NOT to be dry.... Robert Hart wrote: Ian McPhee wrote: Not sure about welding o2 but do know all medical oxygen is all totally dry - the only difference with aviation o2 and medical is the paperwork. Years ago a friend of mine was CEO of the then CIG and we were worried and run a test on moisture on medical cyclinder and it easily meet the aviation std. This is not the advice I received from BOC (they could not guarantee it was dry) - nor my experience. As noted in a previous post, I have had one occurrence of freezing up of the valve during a transfilling operation, which suggests that there is some water present in medical O2 on occasions. -- Regards, Peregrine! _______________________________________________ Aus-soaring mailing list [email protected] To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
