How the Aqua-Lung Scuba Regulator Works

The foundational 1947 patent by Jacques Cousteau and Emile Gagnan for the automatic demand regulator that allows divers to breathe compressed air underwater.

What it covers

This patent describes a two-stage demand regulator that automatically supplies air to a diver only when they inhale. It uses a flexible diaphragm that reacts to the pressure difference between the surrounding water and the air inside the regulator. When the diver inhales, the diaphragm moves, opening a valve to release air from the tank at the exact pressure needed for the depth. This mechanism ensures the diver does not waste air and can breathe naturally regardless of their orientation in the water.

What it doesn't cover

• —Does not cover rebreather systems that recycle exhaled air.
• —Does not cover surface-supplied diving equipment where air is pumped from a boat.
• —Does not cover the design of the high-pressure air cylinders themselves.
• —Does not cover mixed-gas diving systems used for deep technical diving.

The clever bit

The invention uses the ambient water pressure to balance the air delivery, meaning the regulator automatically adjusts to the diver's depth without manual intervention.

Why it matters

This invention effectively created the modern sport of scuba diving. By enabling safe, portable, and autonomous underwater breathing, it transformed ocean exploration from a dangerous professional task into a widely accessible activity.

Real-world examples

• 1.Modern open-circuit scuba regulators
• 2.Recreational diving equipment
• 3.Underwater research gear