Rebreather World - View Single Post - Rate of PO2 drop changes with depth true/false

Sutty · 24th December 2006, 23:10

At 10m, pressure 2atm:

PO2=1.3

FiO2 = 1.3/2 = 0.65 ie 65%O2

For example total loop volume is 10 litres, therefore oxygen content of loop is 10x0.65x2 (x2 to convert to surface-equivalent litres ie mass).
=13 litres O2

At 110m, pressure 12atm:

PO2=1.3

FiO2 = 1.3/12 = 0.10833333

With same 10 litre loop volume, O2 content, adjusted to surface is:
10x0.10833333x12
=13 litres O2

Therefore the mass of O2 is the same in both examples, so given the same oxygen consumption your PO2 will decline at the same rate at whatever depth.

If I am missing something please tell me, if not then a potentially dangerous myth is being promoted.

Neil

24th December 2006, 23:10	#3 (permalink)
Sutty Classic Kiss diver Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Jun 2005 Location: Glossop, Derbyshire, UK Posts: 800	Re: why do we do it? At 10m, pressure 2atm: PO2=1.3 FiO2 = 1.3/2 = 0.65 ie 65%O2 For example total loop volume is 10 litres, therefore oxygen content of loop is 10x0.65x2 (x2 to convert to surface-equivalent litres ie mass). =13 litres O2 At 110m, pressure 12atm: PO2=1.3 FiO2 = 1.3/12 = 0.10833333 With same 10 litre loop volume, O2 content, adjusted to surface is: 10x0.10833333x12 =13 litres O2 Therefore the mass of O2 is the same in both examples, so given the same oxygen consumption your PO2 will decline at the same rate at whatever depth. If I am missing something please tell me, if not then a potentially dangerous myth is being promoted. Neil __________________ Never forget that life is a finite resource.
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