Oxygen regulators, medical type

I'm looking for an inexpensive oxygen system for occasional flights up to 18,000 feet MSL. It seems easy to get a used medical type bottle with a regulator that includes a flow restriction built in. You can select, e.g., a 1 lpm flow rate right on the regulator. But, in a glider, you won't be able to reach this control when it is mounted behind the seat. My question is: with this type of regulator, if you add a flow valve and meter downstream, between that regulator and a cannula, and you open the flow on the medical regulator, but shut the added flow valve (unless and until you reach an altitude high enough to need oxygen), will the flow restrictor on the regulator protect the low-pressure hoses from excessive pressure, or will pressure build up enough to pop the hoses?

A side question is how to re-fill such a bottle.

On Thursday, November 5, 2015 at 6:19:34 PM UTC-5, wrote:
I'm looking for an inexpensive oxygen system for occasional flights up to 18,000 feet MSL. It seems easy to get a used medical type bottle with a regulator that includes a flow restriction built in. You can select, e.g., a 1 lpm flow rate right on the regulator. But, in a glider, you won't be able to reach this control when it is mounted behind the seat. My question is: with this type of regulator, if you add a flow valve and meter downstream, between that regulator and a cannula, and you open the flow on the medical regulator, but shut the added flow valve (unless and until you reach an altitude high enough to need oxygen), will the flow restrictor on the regulator protect the low-pressure hoses from excessive pressure, or will pressure build up enough to pop the hoses?

A side question is how to re-fill such a bottle.

Sounds a bit like do it yourself brain surgery.
Don't be a fool, buy proper equipment. This is a life support system.
UH

On Thursday, November 5, 2015 at 6:56:53 PM UTC-5, wrote:
On Thursday, November 5, 2015 at 6:19:34 PM UTC-5, wrote:
I'm looking for an inexpensive oxygen system for occasional flights up to 18,000 feet MSL. It seems easy to get a used medical type bottle with a regulator that includes a flow restriction built in. You can select, e.g., a 1 lpm flow rate right on the regulator. But, in a glider, you won't be able to reach this control when it is mounted behind the seat. My question is: with this type of regulator, if you add a flow valve and meter downstream, between that regulator and a cannula, and you open the flow on the medical regulator, but shut the added flow valve (unless and until you reach an altitude high enough to need oxygen), will the flow restrictor on the regulator protect the low-pressure hoses from excessive pressure, or will pressure build up enough to pop the hoses?

A side question is how to re-fill such a bottle.

Sounds a bit like do it yourself brain surgery.
Don't be a fool, buy proper equipment. This is a life support system.
UH

I can only second UH! I happened to attend a wave camp in the WVa where one participants decided to use a cheap medical mask on his A8A-regulator. Due to the cold, the mask shrank more than the hose and it fell out of the mask without him noticing. Although he correctly readjusted the flow according to altitude gain and the flow indicator showed 'green', the O2 was not getting to his mask. When it was getting late, we radioed the pilot and he was answering completely incoherent. We talked him into pulling the spoilers. He came down and landed with a huge headache. He stated that he had no recollection of being above 18,000'; the barograph (remember those?;-) )showed that he was well above the wave window's ceiling!
Sorry if I went off on a tangent here but it shows what happens if you skimp on vital equipment. You could end up paying the ultimate price!

Uli
AS

On Friday, November 6, 2015 at 7:04:08 AM UTC-5, AS wrote:
On Thursday, November 5, 2015 at 6:56:53 PM UTC-5, wrote:
On Thursday, November 5, 2015 at 6:19:34 PM UTC-5, wrote:
I'm looking for an inexpensive oxygen system for occasional flights up to 18,000 feet MSL. It seems easy to get a used medical type bottle with a regulator that includes a flow restriction built in. You can select, e.g., a 1 lpm flow rate right on the regulator. But, in a glider, you won't be able to reach this control when it is mounted behind the seat. My question is: with this type of regulator, if you add a flow valve and meter downstream, between that regulator and a cannula, and you open the flow on the medical regulator, but shut the added flow valve (unless and until you reach an altitude high enough to need oxygen), will the flow restrictor on the regulator protect the low-pressure hoses from excessive pressure, or will pressure build up enough to pop the hoses?

A side question is how to re-fill such a bottle.

Sounds a bit like do it yourself brain surgery.
Don't be a fool, buy proper equipment. This is a life support system.
UH

I can only second UH! I happened to attend a wave camp in the WVa where one participants decided to use a cheap medical mask on his A8A-regulator. Due to the cold, the mask shrank more than the hose and it fell out of the mask without him noticing. Although he correctly readjusted the flow according to altitude gain and the flow indicator showed 'green', the O2 was not getting to his mask. When it was getting late, we radioed the pilot and he was answering completely incoherent. We talked him into pulling the spoilers.. He came down and landed with a huge headache. He stated that he had no recollection of being above 18,000'; the barograph (remember those?;-) )showed that he was well above the wave window's ceiling!
Sorry if I went off on a tangent here but it shows what happens if you skimp on vital equipment. You could end up paying the ultimate price!

Uli
AS

Not wanting to beat a dead horse any further but I found this very informative WW-II US Navy training film on this subject:
https://www.youtube.com/watch?v=C6Hg7gzz9jE

Uli
AS

On Thursday, November 5, 2015 at 5:19:34 PM UTC-6, wrote:
I'm looking for an inexpensive oxygen system for occasional flights up to 18,000 feet MSL. It seems easy to get a used medical type bottle with a regulator that includes a flow restriction built in. You can select, e.g., a 1 lpm flow rate right on the regulator. But, in a glider, you won't be able to reach this control when it is mounted behind the seat. My question is: with this type of regulator, if you add a flow valve and meter downstream, between that regulator and a cannula, and you open the flow on the medical regulator, but shut the added flow valve (unless and until you reach an altitude high enough to need oxygen), will the flow restrictor on the regulator protect the low-pressure hoses from excessive pressure, or will pressure build up enough to pop the hoses?

A side question is how to re-fill such a bottle.

I agree with uncl..., would you scuba dive with cobbled together equipment.

The short answer is, yes, the pressure will most probably build to a point that the hoses and/or connections will fail with the system blocked downstream of a simple flow restricting orifice.

Most regulators for aviation use (i.e. Mountain High E & S) have an internal diaphragm that shuts off flow when the downstream pressure equals the upstream pressure. I highly recommend regulators with this feature, for obvious reasons.

At the same time, I can also recognize the (cheaper) alternatives IF YOU DO NOT SHUT OFF THE FLOW COMPLETELY. The pressure will not increase to the point that mechanical components (tubes and connectors) are likely to fail. However, don't forget to turn the flow rate up when you salvage your flight with a low save and are feeling like a superhero for getting back above 12,000. I have heard more than one badly performed bit of karaoke on the radio when somebody forgot to adjust the O2 flow at altitude.

Pressure in the cylinder is often at 2,200 psi or more (using Aviators Breathing Oxygen from a reputable supplier) but nominal pressure is generally from 1,800 to 2,000 psi on a full tank. Most regulators (orifice type) only reduce the pressure to 15-100 psi, and do not shut the flow off when this pressure is reached, allowing the downstream pressure to eventually try to match the much higher cylinder pressure, resulting in failure of the downstream components. Don't worry, your head won't explode, but you might freak out at the sudden pop and hissing noise when it happens. And then the cylinder empties at an enthusiastic rate.

Please extinguish your cigarettes when this happens, or your whole airplane might explode. or at least turn into a merry little fireball.

Regulators with a diaphragm will regulate the pressure to the optimum level needed to operate the delivery mechanism, whether it is an electronic demand system (MH EDS) or a simple flow meter. Medical regulators are not capable of doing anything but reducing pressure to a manageable rate suitable for a constant flow rate with no change in altitude (and therefore increased O2 requirement).

In a nutshell- buy the best stuff for the application (aviation). If you get cheap crap because you are, well, cheap, don't shut off the flow entirely..

It is just your life, so go as cheap as you think it is worth. Remember that Oxygen refills are generally pretty cheap, and unless you have an extremely small cylinder, saving O2 by shutting the flow down doesn't save much in the way of time vs. altitude. Especially when you have to constantly remind yourself to turn it up at altitude or turn it down when the "houses get bigger." The automatic demand systems (M H E&S) take that out of the equation, so you can just concentrate on flying as best you can.

(I have been giving this lecture to hang glider and sailplane pilots since 1988, when I started selling 02 systems. I am also a dealer for M H E&S. In 2014, I got 147 hours of airtime. I was on 02 for 136 of them.)

Have fun, but don't be stupid. Just because you do not use 02 very often does not mean that you should go cheap. Oxygen is fuel for your brain.

Thanks for the advice, Mark. I'd love an EDS system. But here in the East we rarely go high enough to need oxygen, it seems that spending $1000 on a system is overkill for use once a year or so. Also, we have very few convenient places around here to refill, other than at "wave camp".

Do those medical regulators not have a diaphragm? You'd think that's necessary, in order to shut off (at least mostly) the flow coming from the high pressure cylinder? I was guessing they have a diaphragm-based pressure reduction followed by an orifice to set the flow rate, but I may be wrong. And perhaps even the diaphragm system would have some leakage through the high pressure side valve even when it's supposedly shut because the diaphragm senses that the output pressure is high. Then again, these regulators have an "off" position, on the same knob as the non-zero flow rates. If that is simply a zero-size orifice, wouldn't the pressure then build up dangerously in the low-pressure side of that device?

On Thursday, November 5, 2015 at 6:51:25 PM UTC-8, wrote:
Thanks for the advice, Mark. I'd love an EDS system. But here in the East we rarely go high enough to need oxygen, it seems that spending $1000 on a system is overkill for use once a year or so. Also, we have very few convenient places around here to refill, other than at "wave camp".

Do those medical regulators not have a diaphragm? You'd think that's necessary, in order to shut off (at least mostly) the flow coming from the high pressure cylinder? I was guessing they have a diaphragm-based pressure reduction followed by an orifice to set the flow rate, but I may be wrong. And perhaps even the diaphragm system would have some leakage through the high pressure side valve even when it's supposedly shut because the diaphragm senses that the output pressure is high. Then again, these regulators have an "off" position, on the same knob as the non-zero flow rates. If that is simply a zero-size orifice, wouldn't the pressure then build up dangerously in the low-pressure side of that device?

Agree with others... It's life support.
As evidenced in another thread, it's easy enough to get yourself into trouble on the "occasional 18,000' flight". 100% brain power when that happens is fairly important.
Jim

An Aerox system is cheaper than an EDS, maybe half the price. This is life support, as in LIFE, this epitomizes "pound foolish". If you really wanted to save the money on an O2 system, the much smarter choice is to stay at lower altitudes where you do not need it. This is not something to jury rig or kluge together on a budget with parts not designed for this use. Honestly!!!!

On Thursday, November 5, 2015 at 6:51:25 PM UTC-8, wrote:
Thanks for the advice, Mark. I'd love an EDS system. But here in the East we rarely go high enough to need oxygen, it seems that spending $1000 on a system is overkill for use once a year or so. Also, we have very few convenient places around here to refill, other than at "wave camp".

On Thursday, November 5, 2015 at 6:51:25 PM UTC-8, wrote:
Thanks for the advice, Mark. I'd love an EDS system. But here in the East we rarely go high enough to need oxygen, it seems that spending $1000 on a system is overkill for use once a year or so. Also, we have very few convenient places around here to refill, other than at "wave camp".

Do those medical regulators not have a diaphragm? You'd think that's necessary, in order to shut off (at least mostly) the flow coming from the high pressure cylinder? I was guessing they have a diaphragm-based pressure reduction followed by an orifice to set the flow rate, but I may be wrong. And perhaps even the diaphragm system would have some leakage through the high pressure side valve even when it's supposedly shut because the diaphragm senses that the output pressure is high. Then again, these regulators have an "off" position, on the same knob as the non-zero flow rates. If that is simply a zero-size orifice, wouldn't the pressure then build up dangerously in the low-pressure side of that device?

I also agree that you should not cobble an Oxygen System. Please read this article about Hypoxia

http://www.craggyaero.com/hypoxia.htm

Mountain High has the constant flow systems including a cylinder price range from $500 to $600.

http://www.craggyaero.com/xcr_systems1.htm

EDS system with a small bottle about $849

http://www.craggyaero.com/edssystem1.htm

Call to get exact prices and cylinder sizes.

Richard
www.craggyaero.com