US 4,590,951 AGranted

Breathing apparatus

AssigneeRacal Safety Limited

InventorRichard K. O'Connor

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Abstract

A power assisted respirator comprises a facepiece for covering at least the nose and mouth of the wearer which has an outlet provided with a one-way exhale valve which is openable to permit air to flow out of the facepiece when a predetermined pressure P is established within the facepiece. A pump unit supplies air to the space within the facepiece. The pump unit may be connected to an inlet of the facepiece by a flexible hose or may be mounted directly on or in the facepiece. A filter canister is connected to the inlet of the pump means for filtering air supplied to the facepiece. A one-way inlet valve is provided in the path of air flowing from the pump unit to the facepiece and a pressure sensor is provided for sensing the pressure of air in the region of the pump unit inlet for causing deenergisation of the pump unit when the pressure in the region of the pump unit inlet exceeds a predetermined level. The operating parameters of the pump of the pump unit and the exhale valve are selected so that the pressure within the facepiece at which the exhale valve will open slightly exceeds the pressure at the outlet of the pump which will cause the pump to cease or substantially cease operating effectively.

Claims15

Dependent claims

A power assisted respirator comprising a facepiece defining a space for covering the mouth and nose of the wearer and having an inlet and an outlet for air, one-way exhale valve means in said outlet which is operable to permit air to flow out of said space within said facepiece when a predetermined differential pressure is established thereacross, non-positive displacement pump means having inlet means for air and an outlet, said pump means permitting, in its inoperative state, flow of gas between said inlet means and said outlet, battery means connected to said pump means for energizing said pump means, said outlet being connected to the inlet of said facepiece for supplying air thereto, one-way inlet valve means between said pump outlet and said space, said one-way inlet valve means permitting air to flow from said pump outlet to said space through said inlet of said facepiece but not in the reverse direction when the pressue in said space exceeds the pressure at the outlet of said pump means, the operating parameters of said pump means and said exhale valve means being selected so that, during exhalation by the wearer, the inlet valve means will close and the pump means will be placed in a condition in which it will substantially cease to operate effectively, filter means connected to said inlet means of said pump means for filtering air supplied thereto, pressure sensor means connected between said pump means and said filter means for sensing the pressure of air passing between said pump means and said filter means, and control means responsive to said pressure sensor means for causing disconnection of said pump means from said battery means when the pressure sensed by said pressure sensor means rises above a preset level.

A power assisted respirator comprising a facepiece defining a space for covering the mouth and nose of the wearer and having an inlet and an outlet for air, one-way exhale valve means in said outlet which is operable to permit air to flow out of said space within said facepiece when a predetermined differential pressure is established thereacross, non-positive displacement pump means for supplying air to said space within said facepiece and comprising a body having inlet means for air and an outlet connected to the inlet of said facepiece, a fan in said body for moving air from said inlet means to said outlet and a d.c. motor for driving said fan, said pump means permitting, in its inoperative state, flow of gas between said inlet means and said outlet, power means comprising an energisation circuit including battery means connected to said motor for energising said motor, one-way inlet valve means between said pump outlet and said facepiece the space within said facepiece permitting air to flow from said pump outlet to said space through said inlet of said facepiece but not in the reverse direction when the pressure in said space exceeds the pressure at the outlet of said pump means, the operating parameters of said pump means and said exhale means being selected so that, during exhalation by the wearer, said inlet valve means will close and said fan will be placed in a condition in which it will cease or substantially cease to operate effectively, filter means connected to said inlet means of said pump means for filtering air supplied thereto, pressure sensor means connected between said pump means and said filter means for sensing the pressure of air passing between the inlet means of said pump means and said filter means, and control means responsive to said pressure sensor means including a switch operable by said pressure sensor means and connected in said energisation circuit of said motor for causing disconnection of said motor from said battery means when the pressure sensed by said pressure sensor means rises above a preset level.

Dependencies are inferred from the claim text.