Gonna be a pedant here and agree with Nitro rig driver.
A litre is a unit of volume. How can you have a PORTABLE oxygen bottle of 311 litres??????
I doesn't matter if it is at 14.7 psi or 1800 psi the volume will still be 311 litres that's 68 gallons??? that's an awful lot to heft around the cabin or cockpit.
The cabin bottles are 1.5/2/2.5 depending on the size. They too are pressurised to 1800 psi nominal but guess what?? they're still only 1.5/2/2.5 ltr or whatever.
Crew masks are usually 100% on demand. The pax have a constant flow setting.