Diving headgear for use in return-line diving systems

In return-line diving apparatus, exhaust valve means for regulating the flow of used gas from the diver into the return line comprising in combination:

• a. a base structure having inlet and outlet openings therein and an orificed seat between the openings;
• b. a flap pivotally mounted on the base structure with the pivotal axis of the flap lying closely alongside an axially extending margin of the surface of the seat and the flap extending radially outwards over the openings for movement towards and from the seat;
• c. a collapsible peripheral wall connecting the flap to the base structure and forming with the flap a housing for exposure to the ambient water;
• and
• d. a flexible membrane in the housing extending radially outwards between the flap and the seat and having a pair of opposed inner and outer axially extending margins whereof the inner margin is anchored to said margin of the surface of the seat and the outer margin is connected to the flap so that when the flap pivots in response to the diver's breathing the membrane progressively seats and unseats to close and open progressively the orificing of the seat.

In return-line diving apparatus, exhaust valve means for regulating the flow of used gas from the diver into the return line comprising in combination:

• a. a base structure including a base plate having inlet and outlet openings therein and a casing on the base plate extending over the outlet opening and having an orificed seat portion;
• b. a flap pivotally mounted on the base plate at the end of the casing remote from the inlet opening, and extending radially outwards over the seat portion and the inlet opening;
• c. a collapsible peripheral wall connecting the flap to the base plate and forming with the flap a housing for exposure to the ambient water;
• and
• d. a flexible membrane in the housing extending radially outwards between the seat portion and the flap and connected at its inner and outer ends respectively to the casing and to the flap so that on pivotal movement of the flap in response to the diver's breathing there is progressive seating and unseating of the membrane to close and open progressively the orificing of the seat.

In return-line diving apparatus, exhaust valve means for regulating the flow of used gas from the diver into the return line comprising in combination:

• a. a base structure including a base plate having inlet and outlet openings therein and a casing on the base plate extending over the outlet opening and having an orificed seat portion;
• b. a flap pivotally mounted on the base plate at the end of the casing remote from the inlet opening, and extending radially outwards over the seat portion and the inlet opening;
• c. a collapsible peripheral wall connecting the flap to the base plate and forming with the flap a housing for exposure to the ambient water;
• d. a flexible membrane in the housing extending radially outwards between the seat portion and the flap and connected at its inner and outer ends respectively to the casing and to the flap so that on pivotal movement of the flap in response to the diver's breathing there is progressive seating and unseating of the membrane to close and open progressively the orificing of the seat;
• and
• e. shut-off means including an annular seat on the base plate at the inlet opening, and a member on the flap engageable with the seat to close the inlet opening in the event that the gas pressure falls below safety level.

A return-line diving helmet including a shell to enclose the diver's head, a supply regulating valve on the shell responsive to the breathing of the diver to permit a flow of breathable gas from a source into the shell, and exhaust-regulating valve means on the shell responsive to the breathing of the diver to permit a flow of used gas from the shell into a return line, wherein the exhaust regulating valve means include a pair of exhaust valves connected together for series throughflow of used gas and each comprising, in combination:

• a. a base structure having inlet and outlet openings therein and an orificed seat between the openings;
• b. a flap pivotally mounted on the base structure and extending radially outwards over the openings for movement towards and from the seat;
• c. a collapsible peripheral wall connecting the flap to the base structure and forming with the flap a collapsible housing containing the orificed seat and exposable to the ambient water;
• and
• d. a flexible membrane in the housing extending radially outwards between the seat and the flap and connected at its inner and outer ends respectively to the base structure and to the flap so that when the flap pivots in response to the diver's breathing the membrane progressively engages with and disengages from the seat to close and open progressively the orificing of the seat.