Manually tunable, closed-circuit underwater breathing apparatus

摘要

This invention is a manually tunable underwater breathing apparatus (UBA) in which the resonant frequency of the UBA may be adjusted to meet the diver's breathing frequency by controlling the inertance component of the UBA impedance. The principles of the present invention may be adapted to existing UBA by adding a tuning apparatus comprising a valve, a tee and a tuned length of hose. Water displaced by volume change in the breathing bag due to exhalation/inhalation is partly diverted through the valve. Depending on the valve opening set by the diver the inertance and resonant frequency of the UBA can be altered to reduce breathing load.