Mustache conserving cannula require 1/3 of the prescribed flow at any altitude below fl180. So, at fl180 one person requires 1.8l/min /3= 0.6 l/min. Multiply that by 4 people and you get 2.4l/min, which is easily produced by the Sequal Eclipse (actually it makes 3l/min).
I see your drift, Valerio, and this test I did in 2008 supports the much lower o2 usage of the oxysaver cannulas, but have you actually flight tested this and checked everybody’s blood o2 at say FL180, and compared it with what it would be with an individual system for each person? Or alternatively flown with 3 or 4 people at FL180 and checked that say 95% blood o2 is actually achieved?
I ask this because the output pressure of these oxygen concentrators is very low. It is intended to feed one constant flow patient, so if you split up the pipe say 3 or 4 ways, each person’s breathing is going to be taking gas away from the others. The gas cylinder solutions in common use all solve this by using a 1st stage regulator which outputs about 20psi to each person, and then each person has some means of controlling the flow from that – either a demand regulator or a manually adjustable valve.
I looked into buying the Sequal unit and using it with my two O2D2 demand regs but it became obvious this would not work because the output pressure is far too low. It is only what is needed to get air flowing through the zeolite-granule-filled cylinders and I would guess is of the order of a few psi over ambient, max.
However I was also hugely unimpressed with the particular Ebay seller whose correspondence was sporadic at best, gramatically so poor it was almost meaningless (often that is the way these days however!), and whose Ebay trader location was apparently in the UK but whose bank account was apparently in Italy.
Mustache conserving cannula require 1/3 of the prescribed flow at any altitude below fl180. So, at fl180 one person requires 1.8l/min /3= 0.6 l/min. Multiply that by 4 people and you get 2.4l/min, which is easily produced by the Sequal Eclipse (actually it makes 3l/min).
on the nelsonoxygen.com website I found the following statement:
The Oxymizer oxygen conserving cannula (Part No. BD503) is produced by Chad Therapeutics. Oxymizers are very popular and have been used in aviation for many years. The use of the Oxymizer easily doubles the normal duration of oxygen use at 18,000 ft. and triples the use at 10,000 ft.
In the Sequal Eclipse 3 user manual section “Recommended Operating Envirements” they mention the altitude limit of 4000m or 13123ft.
I’m not claiming that the Eclipse is certified for use in a Cirrus. But then neither is an O2D2 despite the fact hundreds of Cirrus pilots use it (and at least one died becasue of it):
Of course I would prefer a product fully certified for the purpose (both in the case of the O2D2 and the Eclipse), but our community is so small that we risk to wait long time. I believe we should help each other to “certify via experience” innovative solutions that can improve our pilot lives without taking unnecessary risks. The Eclipse 2, the civilian version, has been tested by a University checking flow speed, power consumption and oxygen purity up to FL220
altitude where it stopped working. The military version has all pressure and temperature auto-switch-off alarms removed (as the manufacturer confirmed me) which allowed me to use it to FL230 without problems. Plus it is explicitly certified to be used in military helicopters at high altitude (certainly above FL130, which is the conservative limit for the civilian version, not the military). Physically, there is no reason for a concentrator to suddenly stop working at a given altitude, actually according to the above scientific article they work with less effort with altitude probably because of less air density.
[URL’s cleaned up – they didn’t like being bold and in brackets)
There is an Eclipse 3 on Ebay now. How can one tell that is a milspec unit?
Has anyone tested one of these at altitude with multiple people and checked their blood 02 during the flight?
I will try to find it, if successful I will email it to you.
Peter,
there are many Eclipse sellers on Ebay, I cannot recommend one in particular (the one I used was based I think in Netherland or Denmark and peculiarly she had a bank account in Italy as you mention, not sure if she still trades on Ebay. At the time she was the only one selling the military version at reasonable prices). I want to specify I have zero interests on Sequal business…actually I was explicitely invited by you to contribute to this thread :-)
Your 2008 review is very interesting, but if you read the similar scientific paper produced in 2010 (that you mention in your website) it shows the main problem of these results: 2 people can have VERY different oxygen needs at high altitude. For example you and your passenger had 80 vs 86% saturation at the same moment at fl180. In the scientific paper they used a much larger sample of people (but still all very young in age) and 2 could differ by more than 10% (96% vs 86%) saturation at fl180, while having exactly the same saturation at 5000ft. I actually recently discovered that my father needs almost double flow than me at FL190. So, in a way you are right, I would recommend to use the Eclipse with 4 people only for “standard” oxygen users, and with max 2 people for heavy oxygen users.
That’s an interesting point, Valerio. I was rather thinking of the gas not being shared out equally due to different breathing rates of different people but your point is another factor which I think does require a means of individual flow adjustment.
And I don’t think one can do much in that department unless one has more pressure to play with from the start.
That 2008 test flight was set up to not suffer from the problem of different people achieving different blood o2 figures for the same gas flow. We did that simply by adjusting the gas flow so the same blood o2 figure was achieved for the particular person. That way we got a valid comparison of the efficiencies of the various devices at FL180.
There is another thing: I think constant flow cannulas are very bad. Not just for wasting gas (which is not a problem if it costs you nothing) but also because they have problems achieving decent blood oxygenation at higher altitudes. I think the reason why the O2D2 is so good is because
I am sure – but have done no experiments to prove this – that with the O2D2 you would see much less inter-person variation at any given altitude. For example on this flight both myself (54 then) and my son (15 then) were getting 95% at FL200, which is damn good.
There is no way to use the Sequal unit with the O2D2 because the outlet pressure is way too low.
I recall you bought a Sequal 2, and I nearly did too, but the current Ebay one which is a lot more pricey than the others, is a Sequal 3.
Also the one I was looking at didn’t have a battery. I would be happier without that massive lithium battery in case it catches fire – see this article and look at the picture at the very bottom of it. I think that tablet computer came close to catching fire. I suspect many of these large custom-made lithium batteries are poorly made. One needs a backup anyway, which has to be a cylinder…
Sorry Peter, I don’t have the magazine anymore. When I will some time I will try to find it on the website.
Ben
I tried Innogen G2 today at FL160 for less than half an hour. Oxygen level was 98% most of the time. Once I saw 96%. It senses inhalation and squirts oxygen at the beginning, so probably not possible to share with a passenger. The smaller 12-cell battery was showing 4h+ until it shuts down. I didn’t plug it in the 12V outlet, because I’m afraid to blow the fuse. Will try that later. I plan to use it while keeping a bottle as backup, because refills are difficult for me.
@loco many thanks for posting this. I would be really interesting in hearing more about this one.
I didn’t realise it has a built-in demand reg, but really none of the oxygen generators/concentrators are usable for more than one person because their output pressure is too low to usefully divide up.
Did you buy it or borrow it?
