Before WW I Dräger started building breathing apparatus that forced oxygen through the loop.
This was done by means of a suction nozzle. The system used a flow of 2l/min oxygen.
This volume was to big for normal metabolism so overpressure was created in the counterlung.
The additional gas was vented through an overpressure valve.
The system became popular because breathing was light and easy and no poissonous gas could enter the loop.
Several models are build in the period 1904 – 1924 and are called Saugdüsengeräte.
The other popular technique was the use of breathing force to recirculate the gas through the system.
In 1922 Bernhard Draeger wrote an article about these systems (courtesy GlückAuf)
Therebreathersite was founded by Jan Willem Bech in 1999. After a diving career of many years, he decided to start technical diving in 1999. He immediately noticed that at that time there was almost no website that contained the history of closed breathing systems. The start for the website led to a huge collection that offered about 1,300 pages of information until 2019. In 2019, a fresh start was made with the website now freely available online for everyone. Therebreathersite is a source of information for divers, researchers, technicians and students. I hope you enjoy browsing the content!