Oxygen regulators, medical type

What's the difference, if any, in the principle of operation of the regulators in these constant-flow systems vs. the medical ones? (Other then them not having a flow restrictor built in.) In both cases, if the output is blocked (flow valve closed), does the regulator ensure the high input (cylinder) pressure does not bleed into the output?

From what I know about medical regulators, (admittedly, not much, as they aren't aviation oriented systems) is that they are basically pressure reducing constant flow systems not designed to handle a shutoff at the nose (and brain) end.

Some may have the capability to regulate pressure on both sides of the orifice, but do you really want to bet on it? Do some research. I personally think that using a medical system in an aviation environment would be kind of like trusting a dentist to pilot an airliner.

Your choice. Spending $1000 (or less for some actual aviation systems) is not that much, unless you value your life and aircraft at a lesser amount.

If the regulating device has an "off" position, I would assume that is designed to actually reduce the flow to zero with no build up of high pressure that may compromise the system. But, as I said, I don't much care about what they do in a medical environment. I fly airplanes, and hopefully won't have to worry about sucking O2 in a hospital bed for some time. Until then, I will pick an aviation system.

It is possible that the medical system you refer to has lines and connectors between the cylinder and the flow regulator designed to handle the pressures, but I just don't know. It may have the diaphragm to ensure the downstream pressure is handled, but once again, I don't know. There are many medical systems out there, and I really don't want to do much research into them.. I know what works, and your mileage may vary.

If you fly in an area where supplemental O2 is not often required, and you don't need it that often, and you are unfamiliar with its use, I think you should be extra careful to examine the capabilities of the system you choose.

I've been doing this for a long time, and I shake my head at some pilots that think it is simple to just get a bottle of welding gas (fine, as far as it goes) and just stick a hose in their mouth. It is a bit more complicated than that.

Agreed with most of the foregoing.

I'd be a lot more inclined to recommend aerox, if they didn't sell such complete garbage. For instance take a look he

http://wingsandwheels.com/oxygen-equ...ula-masks.html

That clear plastic mask is a total embarrassment, likely to break before first use (that's its best feature -- saves failure at 25K feet). The needle valve and flow meter assembly shown (the one with the right angle valve at the inlet) will almost certainly break on you too. Total rubbish. You guys at W&W ought to be ashamed to carry that stuff.

You can assemble a decent quality aerox system, but you have to pick and choose. Their regulators seem to be okay and the "glow meter" flow meters (see for instance @ Chief aircraft) seem to be rugged enough (well, two seasons and haven't broken mine yet). The blue silicone masks are okay, but seem exorbitantly expensive for what they are. You'll be annoyed when you spend almost $200 and the thing shows up with a tag that says "return to manufacturer by such and such a date for overhaul".

M&H has their issues too. I had a borrowed EDS system fail (wide open) on me in flight at 14,000. Man that was exciting. I talked to M&H about it the next day, they walked me through some basic trouble shooting, finally agreed that the unit was dead, and not repairable. They don't have any built in back up protection, even in the event that the battery just runs down. Really? On a life support system?

So yeah, I agree with the "go for quality -- it's your life" sentiments expressed by others here. Wish the manufacturers shared them.

Best regards,

Evan Ludeman / T8

On Thursday, November 5, 2015 at 9:51:25 PM UTC-5, wrote:
But here in the East we rarely go high enough to need oxygen

A physiologist pointed out to me that a pilot's performance will often benefit from supplemental oxygen well below the levels stipulated by the FAR. If you have an EDS system, you might start to use O2 at a lower altitude than you anticipate.

Related, Dr Dan wrote a good article about the reliability of using a pulse oximeter to evaluate the efficacy of your supplemental oxygen system:

http://www.danlj.org/~danlj/Soaring/...-p18-20-22.pdf

Edited for clarity:

Dr Dan wrote a good article about the UNRELIABILITY of using a pulse oximeter to evaluate the efficacy of your supplemental oxygen system:

http://www.danlj.org/~danlj/Soaring/...-p18-20-22.pdf

Mountain High...

On 11/6/2015 5:52 AM, Tango Eight wrote:
They don't have any built in back up protection, even in the event that the battery just runs down. Really?

I was at 17,900' about 90 miles from home in the Colorado Rockies when
my Mountain High system began chirping its alarm. I flew a high speed
final glide home (there was a lot of lift to reduce descent) thinking I
was out of oxygen. On the ground, I found plenty of O2 in my tank so I
swapped the batteries in the electronic box and everything went back to
normal. I had the batteries in the cockpit but didn't think of swapping
until I was on the ground.

--
Dan, 5J

Perhaps a session in an altitude chamber would change your mind cheap equipment and flying at altitude. The onset of loss of consciousness is incipient- you feel so good you don't even know.

https://www.youtube.com/watch?v=hSrGfElyfVE

Perhaps your club could buy a system for all members to use occasionally?

If I couldn't have quality equipment, I wouldn't do it.

If you can't afford a proper oxygen system, I will give you an A-8 regulator and Oxymizer flow meter if you promise not to try a non certified oxygen system.
johnsinclair210(at)yahoo.com

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?