What is the surface air consumption rate at 20 meters/66 feet of seawater if it is 1.72 bar/25 psi per minute?

To determine the surface air consumption rate and correctly identify the right answer, we need to understand how pressure affects scuba diving air consumption. At deeper depths, the pressure increases, which means a diver consumes air at a higher rate due to the increased ambient pressure.

The given air consumption rate is 1.72 bar (approximately equivalent to 25 psi) per minute at a depth of 20 meters (66 feet). To find the surface equivalent of this air consumption rate, we consider the ambient pressure at that depth. At 20 meters of seawater, the pressure is about 3 bar (2 bar from the water plus 1 bar of atmospheric pressure at the surface).

To convert the consumption at depth to the surface equivalent, we can use the relationship that the air consumption increases in direct proportion to the pressure. Therefore, to find the surface air consumption, we would multiply the underwater consumption rate by the factor of pressure difference.

Calculating gives us:

• Surface air consumption = (depth consumption rate) × (current pressure at depth) = 1.72 bar/minute × (3 bar) = 5.16 bar/minute.

This matches with the reported answer. Thus, the surface air consumption rate is identified as 5