Patent ID: 11865266
Assignee: RESMED PTY LTD
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 18:
19. A vent arrangement for washout of gases from a patient interface, the vent arrangement comprising:
a gas inlet configured to receive gas washout from the patient interface;
a gas outlet configured to expel the gas washout to atmosphere;
a valve comprising a flow surface and a reference surface;
a valve housing; and
a conduit configured to deliver the flow of gas from the gas inlet to the gas outlet, the conduit being defined at least partly by the flow surface and the valve housing,
wherein the reference surface is separated from the flow of gas and the valve is movable to vary a size of the conduit, the valve being configured so that the movement of the valve is caused by a pressure differential between a pressure acting on the flow surface and a pressure acting on the reference surface, and
wherein the conduit is configured so that a flow rate of the gas washout flowing through the conduit increases when a pressure of the gas washout entering through the gas inlet is relatively low and so that the flow rate of the gas washout flowing through the conduit is substantially constant when the pressure of the gas washout entering through the gas inlet is relatively high.