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