What's result on diving air; when the WOB as tested by NEDU of an Inspiration at 300ft on Heliox is 2.98J/L at 75lpm?
If that is the question, AFAIK they certify for no-stop dives with bottom times around 5 minutes tops. That's not long enough to oxtox and shouldn't be long enough to build up CO2 to dangerous levels either. I expect.