SAC terminology

[Robert Helling]

On 14.02.2014, at 08:18, Jef Driesen <jefdriesen at telenet.be> wrote:

> If you ask me, SAC (Surface Air Consumption) defined as pressure/time is pretty useless because it depends on the tank volume. For example a SAC of 1 bar/min is equivalent to 10L/min for a 10L tank, but 15L/min for a 15L tank. While, SAC defined as volume/time is a truly independent number that you can compare across dives, regardless of the tank size.

Totally agree. I think the source of the confusion (i.e. the idea to express it in pressure rather than volume) is that during the dive you carry a pressure gauge rather than a volume gauge. When you always dive with cylinders of the same size pressure per time translates more directly to what you see. But as soon as you dive cylinders of different size the confusion is total.

Best
Robert
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Robert C. Helling     Elite Master Course Theoretical and Mathematical Physics
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                      Ludwig Maximilians Universitaet Muenchen, Dept. Physik
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