UNDERWATER BREATHING APPARATUS

摘要

Breathing gas from a remote source is supplied directly to a diver's helmet, without the requirement of a demand valve. Exhaust gas is returned back to the remote source through a series arrangement of a normally open fail-safe valve and an exhaust control valve which maintains the helmet pressure within predetermined limits relative to the ambient water pressure. Should the exhaust control valve fail in the open position, the fail-safe valve will actuate to insure that the helmet pressure does not decrease to a dangerous level. Valve actuation is a function of diver orientation so as to maintain helmet pressure within a range to minimize diver breathing effort, for the various positional orientations.