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Oxygen - equipment, getting refills, refill hoses, safety, etc

TimR wrote:

no real reason for depressed readings

Cold fingers?

Try the oximeter on somebody else?

It should read 98-99% on the ground at sea level, for non smokers. If not, it is either duff or you have a problem.

Administrator
Shoreham EGKA, United Kingdom

kwlf wrote:

Try the oximeter on somebody else?

I tend to not get much interest in flights that require sticking cannulas up your nose Although I have never really checked carefully I think generally readings were in the very low 90’s even on passengers.

Peter wrote:

It should read 98-99% on the ground at sea leve

Yes indeed the little PULOX device I have does read 98% for me on the ground.

I think the two main issues are either:

  • The oximeter doesn’t function correctly at altitude
  • The MH O2D2 is “calibrated” incorrectly and delivers systematically too little flow.

Are either of those two options technically possible or am I speaking rubbish?

I am ordering a Nonin oximeter as per Peter’s advice and will hopefully be able to rule out the oximeter variable this week.

Last Edited by TimR at 09 Apr 16:35
EGSX

The O2D2 might be faulty. Or the input pressure might be too low. Are you using the MH 1st stage regulator? The O2D2 just does a fixed pulse width and it relies on the correct inlet pressure (in the region of 20psi) to deliver the right mass of gas.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

Are you using the MH 1st stage regulator?

Yep I got this guy:

XCP-FPR-G-DIN477 4-place gauged regulator.
EGSX

@TimR, does the F1 or F2 settings get you back above 98% ?

Nympsfield, United Kingdom

@Xtophe, yes at F2 the saturations go up by a few percent to ~95-96%. I feel like that defeats the conservative nature of the O2D2 though.

EGSX

TimR wrote:

Yes indeed the little PULOX device I have does read 98% for me on the ground.

It was the ‘any altitude’ bit that made me wonder whether it was working correctly. I have little experience with the portable units, but have used one on an expedition which told me a patient had sats of 92%. I was pretty alarmed until I tested it on myself and got the same reading.

They have clearly gotten a lot better in recent years. I’ve known them to be unreliable if people have irregular heartbeats. When they have a poor pick-up for whatever reason, the better ones tell you but some of them start with a low (alarming) sats reading and work their way up to the correct reading. If the number jumps about a lot this could be the problem. Some of them aren’t keen on sunlight or LED light (which can be strobed at frequencies that interfere with them). Cold fingers or earlobes don’t help either.

Arguably if your sats are staying constant then this shows that the Mountain High O2 delivery system is compensating accurately for altitude and keeping them at the minimum acceptable level very successfully. That said, I think I’d prefer to have mine somewhat higher if I were making complex decisions. Does the system make any suggestions as to what saturations it’s trying to achieve?

@kwlf, I have bought another device (one which is apparently proven to be reliable) so will test that this weekend. Presumably sats of ~90% are slightly low for comfort in your world?

kwlf wrote:

Does the system make any suggestions as to what saturations it’s trying to achieve?

Not that I am aware or could find online.

EGSX
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