The rate of gas consumption and the composition of the gas supply depend in part
upon the design of the UBA. Three types of underwater breathing apparatus have
been used successfully to support saturation diving operations: demand opencircuit,
semiclosed-circuit, and closed-circuit.
UBA systems should be designed to support saturation diving excursions of at
least 4 hours duration in temperatures as low as 29°F. Specific information on U.S. Navy certified diving equipment can be found in the applicable systemspecific