Scuba Diving Air Requirements

Question
I am in the process of developing a new type of SNUBA  (Self-contained Not Under Water Breathing Apparatus)unit (similar to the Brownie Third Lung) that is much simpler and much lower in cost than existing designs.  For this design, I need to know the air requirements for a diver at 60' depth, specifically, the volume of air that would be required (ft^3/minute) and the pressure that this volume would be required to be supplied at, at that depth.  Any help would be appreciated.

Answer
Darin,

The air requirements for a diver depend on a multitude of factors.  It has been stated that the "average" diver (I personally have never met or known this person!) consumes 1 ft^3/minute at sea level (1 ATA). Since individual air consumption rates will change within each diver based on personal comfort, physical fitness maintenance, and experience, individual air consumption rates will vary and must be determined from person to person and dive to dive.

Pressure at sea level equals 1 ATA. Every 33 feet of sea water equals 1 ATA of pressure.  So, at a depth of 33 feet, the pressure would be 2 ATA, and at 66 feet of sea water the pressure would be 3 ATA.  Due to the laws of physics, the volume of air needed at a particular depth will increase by the same factor.  Thus, at 33 feet of sea water (2 ATA) consumption for the "average" diver will be 2 ft^3/minute, and at 66 feet of sea water (3 ATA) it will be 3 ft^3/minute.  So, at 60 feet of sea water, the "average" diver would consume 2.73 ft^3/minute.

Again, individual air consumption rates will change within each diver based on personal comfort, physical fitness maintenance, and experience, so individual air consumption rates will vary and must be determined from person to person and dive to dive.

Air must be delivered to the diver at ambient pressure.  At 60 feet of sea water, the ambient pressure would be 2.73 ATA, or 40.3 PSI (1 ATA = 14.7 PSI).

One last time, I cannot stress enough that individual gas consumption rates will change within each diver based on personal comfort, physical fitness maintenance, and experience, so individual air consumption rates will vary and must be determined from person to person and dive to dive.

I hope this helps,

Henry Babcock
AllExperts SCUBA Expert