MASK AND VENT ASSEMBLY THEREFOR
A mask for use with a system for supplying breathable gas pressurised above atmospheric pressure to human or animal's airways includes a mask shell which is, in use, in fluid communication with a gas supply conduit and a gas washout vent assembly. The gas washout vent assembly includes at least one gas washout orifice extending from a first side of the vent assembly positioned, in use, adjacent to human or animal's face and a second side positioned, in use, adjacent the atmosphere. The cross-sectional area of the orifice at the first side is larger than the cross-sectional area of the orifice at the second side.
1 . A mask for use with a system for supplying breathable gas pressurised above atmospheric pressure to a human or animal's airways, the mask includes a mask shell which is, in use, in fluid communication with a gas supply conduit; and a gas washout vent assembly, the gas washout vent assembly includes at least one gas washout orifice extending from a first side of the vent assembly positioned, in use, adjacent the human or animal's face and a second side positioned, in use, adjacent the atmosphere and the cross-sectional area of the orifice at the first side is larger than the cross-sectional area of the orifice at the second side.
2 . A mask as claimed in claim 1 , wherein the orifice includes a first substantially cylindrical portion adjacent the first side, a second cylindrical portion adjacent the second side and a tapering portion between the first and second substantially cylindrical portions.
3 . A mask as claimed in claim 2 , wherein the second substantially cylindrical portion and the tapering portion are of approximately equal thickness in the axial direction of the orifice and are thicker than the first substantially cylindrical portion.
4 . A mask as claimed in claim 1 , wherein the vent assembly includes a plurality of said orifices therethrough.
5 . A mask as claimed in claim 4 , wherein each of said orifices is separated from the other(s) of said orifices by at least the diameter of the orifice at the second side.
6 . A mask as claimed in claim 1 , wherein the mask shell and/or conduit is formed from a relatively rigid material and the vent assembly is an insert of relatively flexible elastomeric material and is attachable to the mask shell or conduit.
7 . A mask as claimed in claim 6 , wherein the mask shell and/or conduit is formed from polycarbonate and the insert is formed from Silastic™ or Santoprene™.
8 . A mask as claimed in claim 6 , wherein the insert includes a groove around its periphery, the groove adapted to locate the insert against a correspondingly sized rim of an opening formed in the mask shell or conduit.
9 . A mask as claimed in claim 6 , wherein the insert is substantially crescent shaped.
10 . A vent assembly for the washout of gas from a mask or conduit used with a system for supplying breathable gas pressurized above atmospheric pressure to a human or animal, the vent assembly includes at least one gas washout orifice extending from a first side of the vent assembly placed, in use, adjacent the human or animal's face to a second side placed, in use, adjacent the atmosphere, the cross-sectional area of the orifice at the first side is larger than the cross-sectional area of the orifice at the second side.
11 . A vent assembly as claimed in claim 10 , wherein the orifice includes a first substantially cylindrical portion adjacent the first side, a second cylindrical portion adjacent the second side and a tapering portion between the first and second substantially cylindrical portions.
12 . A vent assembly as claimed in claim 11 , wherein the second substantially cylindrical portion and the tapering portion are of approximately equal thickness in the axial direction of the orifice and are thicker than the first substantially cylindrical portion.
13 . A vent assembly as claimed in claim 10 , wherein the vent assembly includes a plurality of said orifices therethrough.
14 . A vent assembly as claimed in claim 13 , wherein each of said orifices is separated from the other(s) of said orifices by at least the diameter of the orifice at the second side.
15 . A vent assembly as claimed in claims 10 , wherein the mask shell and/or conduit is formed from a relatively rigid material and the vent assembly is an insert of relatively flexible elastomeric material and is attachable to the mask shell or conduit.
16 . A vent assembly as claimed in claim 15 , wherein the mask shell and/or conduit is formed from polycarbonate and the insert is formed from Silastic™or Santoprene™.
17 . A vent assembly as claimed in claim 15 , wherein the insert includes a groove around its periphery, the groove adapted to locate the insert against a correspondingly sized rim of an opening formed in the mask shell or conduit.
18 . A vent assembly as claimed in claim 15 , wherein the insert is substantially crescent shaped.