Demand regulator having adjustable air flow

摘要

A demand regulator for self-contained underwater breathing apparatus has a housing and a cover forming a breathing chamber with a mouthpiece. A diaphragm on the chamber is movable with changes in pressure due to user inhalation demand. An inlet valve coupleable to a supply of pressurized air is responsive to the position of the diaphragm. At least one manually adjustable fin can be retracted or positioned across the air flow path through the chamber, for setting the extent of venturi effects tending to displace the diaphragm and open the valve to free flow in the absence of inhalation demand. The venturi adjustment mechanism has a sealed rotatable arm with a radially extending end in sliding engagement with the fin, and preferably the fin has two resilient strips that are spaced apart by a dimple.