Valves

Claim 2

A valve for directing flow of breath to and from a patient, having a first port adapted to be connected to a source of breath, a second port adapted to be connected to a patient, a third port adapted to convey exhaled breath from the valve, a passage between said second and third ports, a first obturating member for controlling flow between said first and second ports, said obturating member comprising a diaphragm secured at its periphery and having an intact outer portion ensuring unidirectional flow from said first port to said second port and a central apertured portion for allowing continuous communication between said second port and said passage, and a second obturating member for controlling flow between said passage and said third port and arranged to prevent flow through said passage when said first obturating member allows flow between said first and second ports.

Claim 3

A valve as claimed in claim 1, wherein the central apertured portion is provided with circumferentially spaced apart apertures.

Claim 4

A valve for directing flow of breath to and from a patient, having a first port adapted to be connected to a source of breath, a second port adapted to be connected to a patient, a third port adapted to convey exhaled breath from the valve, a passage between said second and third ports, a first obturating member for controlling flow between said first and second ports, through which obturating member said second port is in continuous communication with said passage, and a second obturating member for controlling flow between said passage and said third port and arranged to prevent flow through said passage when said first obturating member allows flow between said first and second ports, said second obturating member comprising a diaphragm, one side of which is arranged to be subjected, in use, to the pressure of flow through the first port to urge said diaphragm into a closed position to prevent flow from said passage, the pressure of which is arranged to act on a first portion of the other side of said diaphragm, a second portion of said other side being subjected to pressure through the third port.

Claim 5

A valve for directing flow of breath to and from a patient, having a first port adapted to be connected to a source of breath, a second port adapted to be connected to a patient, a third port adapted to convey exhaled breath from the valve, a passage between said second and third ports, a first obturating member for controlling flow between said first and second ports, through which obturating member said second port is in continuous communication with said passage, and a second obturating member for controlling flow between said passage and said third port and arranged to prevent flow through said passage when said first obturating member allows flow between said first and second ports, said second obturating member comprising a diaphragm, one side of which is arranged to be subjected, in use, to the pressure of flow through the first port to urge said diaphragm into a closed position to prevent flow from said passage, the pressure of which is arranged to act on a first portion of the other side of said diaphragm, a second portion of said other side being subjected to pressure through the third port.

Claim 6

A valve as claimed in claim 3, wherein said first portion is greater than said second portion.

Claim 7

A valve as claimed in claim 3, wherein said second diaphragm has a substantially rigid flat portion arranged to engage with seating means in said closed position.

Claim 8

A valve as claimed in claim 5, wherein said seating means comprise blunt knife-edged projections.

Claim 9

A valve as claimed in claim 6, wherein said first portion is annular and said second portion is disposed inwardly thereof, said projections comprising an inner rim engageable with the second diaphragm at the junction of said first and second portions and an outer rim.

Claim 10

A valve as claimed in claim 7 wherein said projections include a further rim intermediate said inner and outer rims.

Claim 11

A valve for directing flow of breath to and from a patient, having a first port adapted to be connected to a source of breath, a second port adapted to be connected to a patient, a third port adapted to convey exhaled breath from the valve, a passage between said second and third ports, a first obturating member for controlling flow between said first and and second ports, through which obturating member said second port is in continuous communication with said passage, said passage being part annular and surrounded by, though separate from, a part annular channel which connects said first port to said second port via said first obturating member, and a second obturating member for controlling flow between said passage and said third port and arranged to prevent flow through said passage when said first obturating member allows flow between said first and second ports.

Claim 12

A valve for directing flow of breath to and from a patient, having a first port adapted to be connected to a source of breath, a second port adapted to be connected to a patient, a third port adapted to convey exhaled breath from the valve, a passage between said second and third ports, a first obturating member for controlling flow between said first and and second ports, through which obturating member said second port is in continuous communication with said passage, said passage being part annular and surrounded by, though separate from, a part annular channel which connects said first port to said second port via said first obturating member, and a second obturating member for controlling flow between said passage and said third port and arranged to prevent flow through said passage when said first obturating member allows flow between said first and second ports.

Claim 13

A valve for directing flow of breath to and from a patient, having a first port adapted to be connected to a source of breath, a second port adapted to be connected to a patient, a third port adapted to convey exhaled breath from the valve, a passage between said second and third ports, a first obturating member for controlling flow between said first and second ports, through which obturating member said second port is in continuous communication with said passage, and a second obturating member for controlling flow between said passage and said third port and arranged to prevent flow through said passage when said first obturating member allows flow between said first and second ports, said second obturating member comprising a diaphragm made of thin latex rubber, with a thin flat substantially rigid disc fixed to its central portion and arranged to engage with seating means when said second obturating member is in the closed position.

Claim 14

A valve for directing flow of breath to and from a patient, having a first port adapted to be connected to a source of breath, a second port adapted to be connected to a patient, a third port adapted to convey exhaled breath from the valve, a passage between said second and third ports, a first obturating member for controlling flow between said first and second ports, through which obturating member said second port is in continuous communication with said passage, and a second obturating member for controlling flow between said passage and said third port and arranged to prevent flow through said passage when said first obturating member allows flow between said first and second ports, said second obturating member comprising a diaphragm made of thin latex rubber, with a thin flat substantially rigid disc fixed to its central portion and arranged to engage with seating means when said second obturating member is in the closed position.

Claim 15

A valve as claimed in claim 10, further including a tapering passageway located radially inwardly of said passage and in communication with said third port, and wherein said seating means comprises an inner annular blunt knife-edged projection at the opening of said tapering passageway and an outer blunt knife-edged annular projection at the opening of said passage, the edges of said projections being co-planar.

Claim 16

A valve as claimed in claim 11, wherein an intermediate blunt knife-edged annular projection is provided between said inner projection and said outer projection, the edge of said intermediate projection being co-planar with the edges of said inner and outer projections.