Oxygen regulators, medical type

OK, Moshe, apparently you aren't reading this. You are still in the dark about what I am saying. ALL Regulators have a flow restrictor. That is what they do. (Got it?) SOME regulators do not prevent the pressure from building up on the low pressure side. SOME have a diaphragm that keeps the pressure on the low side from equaling the high side pressure if the flow is shut off completely. These are designed for aviation. Medical regulators are not designed for aviation. You are planning to use this in aviation. Use a regulator and system designed for aviation. Can I be any more clear?

Mark, please stop shouting. I am trying to learn how these systems are designed. Whether medical or aviation, their purpose is to convert a very high and non-constant pressure (in the cylinder) into a constant flow at low pressure (into your cannula or mask). Here is what I've garnered so far, which may or may not be correct, but give me facts not labels:

A "pressure regulator" per se regulates pressure, not flow. *IF* its output pressure is constant, then the flow from there through a given small orifice will be constant, even as the source cylinder pressure decreases as the oxygen is used up. This orifice is the flow regulator, separate from the pressure regulator. It operates at a much lower pressure (20-50 PSI) than the cylinder pressure (1000-2000 PSI).

These two "regulators" may be combined in the same physical unit, or separated by a hose. For use in a glider where you cannot reach (or even look at) the pressure regulator on the cylinder, you would want the flow regulator separated and within reach. A typical pellet type flow meter which has a needle valve to adjust the flow then serves as the flow regulator. The pressure in the hose upstream of that meter needs to be reasonably low (say under 50 PSI). If you close that flow valve, what keeps the hose pressure from building up? That's the job of the pressure regulator.

There is a diagram of a diaphragm type pressure regulator here, making its operation clear:
https://en.wikipedia.org/wiki/Pressure_regulator

My question relates to the high pressure valve that is operated by the diaphragm of the pressure regulator, labeled a "poppet" in that diagram. When "closed", to what extent does it leak?

Dear Moshe..

The reason people are getting frustrated as it is not just your life you are risking but those on the ground and in the air with you. If you want to know about medical oxygen systems contact a medical supplier. You keep asking questions like you are going to try to build an aviation oxy system out of medical oxy system, stop it, that is incredibly, selfish and stupid. I have never insulted anyone on this group, but come on!

I had the proper oyx system and on one flight I noticed I was not making good decisions, was confused about what my computer was telling me and I ended up landing with full ballast without knowing until the ship felt heavy on roll out (could have had a nasty fatal stall as I did not fly faster for higher wing loading). Had kink in the plastic tubing. After that I started to fly with a oxymeter on my finger. Point being do not take chances with life support, period end of story! If you cannot figure this out, you should not be driving let alone flying. As I said earlier, if you do not want to spend the $400 it takes for an oxy system, stay below 12,500. But frankly I would have to question any of your judgement, due to your persistent line of questioning. How about asking if anyone has a used aerox system for sale instead?


On Friday, November 6, 2015 at 9:35:49 AM UTC-8, wrote:
Mark, please stop shouting. I am trying to learn how these systems are designed. Whether medical or aviation, their purpose is to convert a very high and non-constant pressure (in the cylinder) into a constant flow at low pressure (into your cannula or mask). Here is what I've garnered so far, which may or may not be correct, but give me facts not labels:

A lot of people are flying with systems designed for aviation but made 20, 40, even 60 years ago. And besides mechanical failures, other things can go wrong - see some anecdotes posted above and below, such as kinks in hoses, hoses pulled off of a fitting, etc. No matter how official and expensive a system is, I would use a flow meter to verify the flow (and still need to check that hose still reaches the mask etc). An exception is an EDS system, for which a flow meter is useless. But at least you can feel the puffs of gas in your nose (if using a cannula), and the EDS at least has built-in alarms for some sorts of faults.

Amazing, with all due respect a class in logic might help. If systems designed and tested for aviation can fail then what are the chances of a medical system not designed nor tested for aviation could fail. I wrote of the kinked hose, and took steps to not have that happen again, plus I now fly with EDS. I did not have a logic jump that thought "gee this system was designed for aviation and failed, so why don't I make a system out of the cheapest parts I can. If you are oxygen depraved you will not be checking a flow meter, nor understand what it is telling you. Did you notice how no thinks this is a good idea?

Sounds like a candidate for the darwin award, and the absolute fixed thinker award. I remember seeing a news clip about an idiot that was trying to fill a gas tank at night from a can, couldn't see so they lit a match.



On Friday, November 6, 2015 at 11:13:08 AM UTC-8, wrote:
A lot of people are flying with systems designed for aviation but made 20, 40, even 60 years ago. And besides mechanical failures, other things can go wrong - see some anecdotes posted above and below, such as kinks in hoses, hoses pulled off of a fitting, etc. No matter how official and expensive a system is, I would use a flow meter to verify the flow (and still need to check that hose still reaches the mask etc). An exception is an EDS system, for which a flow meter is useless. But at least you can feel the puffs of gas in your nose (if using a cannula), and the EDS at least has built-in alarms for some sorts of faults.

This reminds me of a BG-12 owner I knew a while back. He cut a 12 X 12 " hole in the aft fuselage, so he could inspect and lube things in there. Fitted his custom hatch with a couple of hinges and a little sliding latch. Several pilots tried to tell him he had drastically weakened the structure, because the skin was most of the structure.
He wouldn't hear a word of it.
About 6 months later, he didn't return after the days flying. Search plane found the wreckage near Strawberry strip. We couldn't tell if the boom broke in flight or during what looked like a cart-wheel maneuver, but the fuselage broke right through his little hatch!
I figure 2% will never get the word,
JJ

On Friday, November 6, 2015 at 11:35:49 AM UTC-6, wrote:
Mark, please stop shouting. I am trying to learn how these systems are designed.

What you originally said was that you were looking for a cheap alternative to an actual piece of aircraft life support equipment, based on medical discards.

I'm surprised everyone who has answered you HASN'T DONE IT IN ALL CAPS!!!!

So - the answer to your original post is: DON'T EVEN GO THERE, GET A REAL AIRCRAFT O2 SYSTEM!

If price is so important, check out the XCR system (http://www.craggyaero.com/xcr_systems1.htm) or look around for a used system.

Sometimes, it takes people shouting at someone to keep them from doing something really stupid. BTDT!

Cheers,

Kirk
66

On 11/6/2015 10:35 AM, wrote:
...I am trying to learn how these systems are
designed.

The questions you're asking, and the information you want, are/is best
answered/obtained through direct contact with the manufacturers of the
equipment (as opposed to, say, technical sales representatives *representing*
those companies - who themselves [in my engineering experience] are variously
informed from "well" to "not so well.") In the halcyon days of yore, this
often meant digging through a Thomas Register or similar; today the WWW will
likely suffice. But in any case it will likely involve several phone calls and
being routed around inside the home office until you find/are-punted-to
someone on the design side of the product, after (most likely) the people
answering the phones first direct you to (maybe even technical!) sales.

HTH.

Bob W.