04-30-2004, 07:42 PM
The efficiency of the RB80 will increase with depth, but this is a matter of physics and physiology, not "useage". The human body "consumes" about 1.0 liter of O2 per minute at 1 ATA. This consumption is fairly consistent regardless of depth (the amount of O2) so it will be contained in smaller and smaller "volumes" of gas at depth. This is why the FO2 at depth with the RB80 is so much closer to your source gas. The RB80 keeps the FO2 more consistent than other semi-closed systems, but gas usage at depth does increase. This is all a result of the RMV-keyed counterlung. 