Diving equipment with semi-closed circulation and gas exchange with water

摘要

A completely autonomous aqualung is described in which a passive, diffusion-controlled gas exchange takes place, with the aid of a membrane gas exchanger, between the respiratory-gas circulation and the surrounding water. Nitrogen diffuses, through a membrane which is gas permeable but impermeable to water, from the surrounding water into the equipment, and carbon dioxide and part of the oxygen diffused from the equipment system outwards. As a result, a reduction of the oxygen partial pressure is achieved in the circulation in the equipment, which permits use of the equipment to approximately twice the depth, compared to the conventional oxygen circulation apparatuses, while carbon dioxide is eliminated to a sufficient extent at the same time. Furthermore, when using this equipment decompression is no longer necessary even at depths greater than 10 m, as the nitrogen partial pressure never exceeds its atmospheric value. Oxygen supply is effected via a metering valve from pressure bottles, so that long diving times can be achieved; the only limiting factor is the oxygen supply. Dimensions and weight are comparable to conventional oxygen apparatuses.