What gas volume is used by a diver at 100 fsw for 30 minutes?

To determine the gas volume used by a diver at 100 feet of seawater (fsw) for a 30-minute dive, we first need to take into account the pressure at that depth and the effects of breathing gas consumption. At 100 fsw, the pressure is approximately three atmospheres (1 atmosphere from the surface plus 2 additional atmospheres from the water column).

Divers typically use the concept of "cubic feet per minute" (CFM) to assess their gas consumption rates. For many recreational divers, the average air consumption rate is around 0.5 to 1 cubic foot per minute at depths commonly used in recreational diving.

Assuming an average consumption of 0.5 ft³/min, over a 30-minute dive at 100 fsw:

0.5 ft³/min × 30 min = 15 ft³ of gas.

However, due to the increased pressure underwater, the volume of gas consumed must be calculated relative to the pressure at that depth, which means it would technically require more than this amount of gas for the diver to breathe adequately.

To determine the total gas volume required at that depth, we multiply the surface volume (the volume of gas at the surface) by the