Evaluation of the effect of nozzle diameter on the breathing performance of a diving breathing apparatus

The article was inspired by information in the literature regarding damage to medium-pressure diving hoses, which, as a result of the crystallisation of material on their inner surface and the detachment of particles, caused significant interference with the output of the pressure regulator. A dangerous consequent 'clogging' of the airflow in stage II of the breathing apparatus and an increase in the effort in the diver's lungs to overcome the increased breathing resistance resulted. This problem was investigated in the paper. Nozzles with reduced diameters were fabricated to simulate the deterioration of the automaton conditions. A suitably selected regulator from a domestic manufacturer's was used for the tests. A series of measurements was carried out in a breathing simulator for the established experimental conditions specified in the standard PN-EN 250:2014. Following the test, the results obtained were analysed and interpreted based on statistical description methods.