# 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.

- **Patent:** US 2485039
- **Original title:** Diving unit
- **Owner:** Individual
- **Granted:** 1949
- **Status:** Public domain (expired)
- **Times cited:** 12
- **Field:** mechanical, consumer_electronics

## What it does

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 does NOT 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.

## Real-world examples

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

## 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.

## Frequently asked questions

### What does How the Aqua-Lung Scuba Regulator Works cover?

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

### Who owns patent US 2485039?

Individual owns this patent, granted in 1949.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 2485039 cited by?

This patent has been cited by 12 later patents that build on its ideas.

### What problem does this patent solve?

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.

### What does this patent NOT cover?

Does not cover rebreather systems that recycle exhaled air.

**Full plain-English explainer:** https://patentbrief.org/patent/us/2485039/aqualung-scuba-cousteau-gagnan

**Original patent:** https://patents.google.com/patent/US2485039

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._


## Related patents

Semantically similar inventions in the PatentBrief corpus:

- [How the Iron Lung Artificial Respirator Works](https://patentbrief.org/patent/us/1906844/iron-lung-respirator-drinker) — A 1933 patent for a mechanical respirator that uses external air pressure changes to force a patient's lungs to expand and contract.
- [How Dr. Forrest Bird's Mechanical Respirator Controls Patient Breathing](https://patentbrief.org/patent/us/3191596/bird-respirator-ventilator) — A 1965 patent describing a mechanical ventilator that automatically switches between inhaling and exhaling based on pressure levels in a patient's airway.
- [How the First Heart-Lung Machine Oxygenated Blood](https://patentbrief.org/patent/us/2702035/heart-lung-machine-gibbon) — A 1955 invention that allowed surgeons to oxygenate a patient's blood outside the body, enabling the first successful open-heart surgeries.
- [How Lewis Waterman's Original Fountain Pen Design Worked](https://patentbrief.org/patent/us/293545/fountain-pen-waterman) — This 1884 patent describes an early fountain pen designed by Lewis E. Waterman, which aimed to solve common ink-flow problems, making writing smoother and cleaner.
- [How the First Modern Water Slide Was Designed](https://patentbrief.org/patent/us/2982547/slip-n-slide-carrier) — A 1960 patent for a water-based amusement structure featuring a sloped surface and a water supply system to create a sliding experience.