Hello,
I just bought a new Suunto D4i. Used it for the first time on my nitrox/deep speciality courses last week.
For some odd reason however, it would not allow me to plan dives deeper than 36.0 meters at 1.4 pO2/EAN 28. This is even though in theory, the 1.4 limit is reached at 40 meters on EAN 28. I had to re-adust the pO2 to 1.5 so that alarms don't start going off beyond 36.0 meters.
Is this just conservative accounting for a possible margin of error or is there some other reason?
Many thanks in advance.
Yes, there is another reason. In theory, MOD of EAN28 is 40 m, but that is assuming ideal gas laws. However in real world, especially over 200 bars / 3000 psi, ideal gas laws deviate from "real" gas laws. Suunto's are using "real" gas laws, hence the numbers are slightly different than you expect them to be.
If you have the Dive Manager (as of version 3.1), you could change the gas laws in the settings and see the effects on the dive plans.