BREATHING RESISTANCE IN SCUBA COMPONENTS.

Abstract

This study was made to determine the relative effects of cross-sectional area, length, configuration, and other physical characteristics upon 'breathing resistance' (overall pressure drop per unit volumetric flow) at depth of various components found in scuba. Breathing machine results upon the various components selected for the study are summarized as tables of peak respiratory pressure against depth. The results are discussed constructively and lead to specific conclusions about the various types of components. Folded breathing tubes have inherently higher resistance than molded tubes. Of the various check valves, the rubber disk J-valve has the best resistance characteristics while the mushroom, mica disk, and flutter valves have poor resistance characteristics. Of the CO2 absorbent canisters, the radial canister has the best resistance characteristics, but the cylindrical canister generally has a more practical configuration. The rectangular canister has poor resistance characteristics. Baralyme and Soda Lime, the two most common absorbents, produce the same resistance characteristics when dry. Special fittings of 1-inch diameter and various configurations do not produce noteworthy resistance in a 2-inch length. (Author)