I'm writing a few notes on my oxygen setup, as well as my measured usage to determine tank size, length of flight, etc. This is stuff I couldn't find with google before getting some gear, so hopefully it's useful to some newb like me.
I recently picked up a few items to start flying with oxygen. I use medical type gear I found on craigslist for next to nothing, with continuous flow regulators, and a pendant style oxymizer cannula. My thinking is that the reservoir in this style cannula might help conserve oxygen by allowing a lower flow rate.
I use a finger pulse oximeter. I shoot for an oxygen sat of 94-97 percent. I felt fine at 88-91, but if I see these values, I increase flow. I may run leaner in the future, but I'm starting conservative. It's worth noting that the blood's oxygen carrying capacity really starts dropping below a sat of 88%, so that is a hard cutoff for me.
With a 170L bottle, I flew to 17,500ft on a test flight. I started 1L at 8000 ft, 2 L at 10,000 ft, and 4L at 16,000 ft. This was based on pulse ox readings, and conservative. Total oxygen usage time was about 30 min. At the end of the flight I had 1600 psi in the tank, from about 2100 psi, so used maybe 500 psi. If you equate pressure to volume as a 1 to 1 ratio, I used about 1/4 off the tank. Theoretically, this tank should last about 85 min at 2L and 42 min at 4L, so this matches my actual usage numbers pretty well.
I also made a flight with a 680L cylinder at 14,500-15,500 ft at 2.5L for about 105 min.
The tank started a little over 2000 psi and at end reads 1000 psi, so used maybe 1000 psi.
I calculate i should have used 777 psi:
105 min * 2.5 L/min * 2.96 psi/L/min = 777 psi
I'll admit, I didn't do a great job of marking my times and numbers precisely on this flight, which may account for the discrepancy. I'll post more here as I make more flights.
A 680L cylinder is rated for 2015 psi, so that's 2.96 psi/L/min as a rough conversion to figure out how long the tank should last. This is based on the ideal gas laws which aren't very precise, so a safety margin is mandatory.
I recently picked up a few items to start flying with oxygen. I use medical type gear I found on craigslist for next to nothing, with continuous flow regulators, and a pendant style oxymizer cannula. My thinking is that the reservoir in this style cannula might help conserve oxygen by allowing a lower flow rate.
I use a finger pulse oximeter. I shoot for an oxygen sat of 94-97 percent. I felt fine at 88-91, but if I see these values, I increase flow. I may run leaner in the future, but I'm starting conservative. It's worth noting that the blood's oxygen carrying capacity really starts dropping below a sat of 88%, so that is a hard cutoff for me.
With a 170L bottle, I flew to 17,500ft on a test flight. I started 1L at 8000 ft, 2 L at 10,000 ft, and 4L at 16,000 ft. This was based on pulse ox readings, and conservative. Total oxygen usage time was about 30 min. At the end of the flight I had 1600 psi in the tank, from about 2100 psi, so used maybe 500 psi. If you equate pressure to volume as a 1 to 1 ratio, I used about 1/4 off the tank. Theoretically, this tank should last about 85 min at 2L and 42 min at 4L, so this matches my actual usage numbers pretty well.
I also made a flight with a 680L cylinder at 14,500-15,500 ft at 2.5L for about 105 min.
The tank started a little over 2000 psi and at end reads 1000 psi, so used maybe 1000 psi.
I calculate i should have used 777 psi:
105 min * 2.5 L/min * 2.96 psi/L/min = 777 psi
I'll admit, I didn't do a great job of marking my times and numbers precisely on this flight, which may account for the discrepancy. I'll post more here as I make more flights.
A 680L cylinder is rated for 2015 psi, so that's 2.96 psi/L/min as a rough conversion to figure out how long the tank should last. This is based on the ideal gas laws which aren't very precise, so a safety margin is mandatory.
