Tests of the Present HeO2 Tables, the Determination of CO2 and O2 Percentages at Various Stages of the Dives and the Comparison of the Present Venturi Recirculation System with the Revised Type with Special Regard to the Effective CO2 Concentration at Depths Ranging from Atmospheric to 429 Feet.

Abstract

It was found that the average bottom effective CO2 with the use of the standard recirculating system ranged from 1 to 1.5percent with occasional deviations up to 3percent. The effective CO2 in ascent was quite low and never in the danger zone. The new venturi combination reduced the above bottom effective CO2 by 43percent. Sixty-eight (68) parallel dives were used for comparison. There was no increase in gas consumption, but rather a slight decrease. The CO2 reductions occurred at all stages of the dive although the percentage was not calculated in ascent as the values were originally quite low. The venturi supply pressure should be maintained at 100 psi over bottom for depths of 250 feet or more. The tables used in these dives were satisfactory in warm water. Four bends occurred out of 144 dives. The incidence of bends was 2.78percent. The ascent and descent rates were also satisfactory.