Compact Recreational Rebreather With Innovative Gas Sensing Concept and Low Work of Breathing Loop Design

Recreational rebreathers are increasingly popular, and recreational diver training organizations now routinely offer training for rebreather diving. Few rebreathers on the market, however, fulfill the criteria of a dedicated recreational rebreather. These remain based on traditional sensor technology, which may be linked to rebreather use having an estimated 10 times the risk of mortality while diving compared with open circuit breathing systems. In the present work, a new recreational rebreather based on two innovative approaches is described. Firstly the rebreather uses a novel sensor system including voltammetric and spectroscopic validation of galvanic pO(2) sensor cells, a redundant optical pO(2) sensor, and a two-wavelength infrared pCO(2) sensor. Secondly a new breathing loop design is introduced, which reduces failure points improves work of breathing, and can be mass fabricated at a comparatively low cost. Two prototypes were assembled and tested in the laboratory at a notified body for personal protective equipment before both pool and sea water diving trials. Work of breathing was well below the maximum allowed by the European Normative. These trails also demonstrated that optical pO(2) sensors can be successfully employed in rebreathers. The pCO(2) sensor defected pCO(2) from 0.0004 to 0.0024 bar. These new approaches, which include a new concept for simplified mechanical design as well as improved electronic control, may prove useful in future recreational diving apparatus