I don't recall exactly. I carried a pulse oximeter to keep tabs on O2
saturation. Take a look at this link:
http://www.c-f-c.com/gaslink/docs/abo4.htm
http://www.c-f-c.com/gaslink/docs/abo4.htm . Using that it appears
that 1 lpm/10,000' is the FAA recommended flow rate. Therefore, 1.8 lpm
at 18,000', but I'm certainly no expert and you'll have to make your own
choices.

Dan

On 4/5/2016 1:04 PM, pgs wrote:
On Tuesday, April 5, 2016 at 10:52:19 AM UTC-4, Dan Marotta wrote:
Those cheaply made flow meters are for the birds. I bought medical
grade panel-mount flow meters for my Sinus (experimental) at 2/3 the
cost and they're far superior in materials and quality. If you
don't have panel space to mount one, you could lay it in your lap
just like the other one, though it's a bit more substantial. Here's
a link to an example: https://www.dwyer-inst.com/Product/F...Area/SeriesOMA

Dan, what flow rate is used for what altitude?

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Dan, 5J