Breathing apparatus
First Claim
1. A breathing apparatus comprising:
- a motor-driven fan;
filter means connected to the fan for removing one or more unwanted components from air drawn into the apparatus from the external atmosphere by operation of the fan;
a breathing interface means connected to receive such filtered air;
a differential pressure sensor comprising a flexible pressure-responsive member so connected to the apparatus as to be exposed on its opposite sides respectively to the pressure within the apparatus downstream of at least a stage of said fan and the pressure within the apparatus upstream of at least said stage of said fan or atmospheric pressure, and whereby in the event of destruction of or permeability of said pressure-responsive member to a said unwanted component the connection of the pressure sensor provides no pathway from the external atmosphere to said breathing interface means which does not also include said filter means; and
control means for controlling the operation of the fan motor in response to said sensor whereby to reduce the throughput of the fan in response to an increase in the pressure differential sensed by the sensor and to increase the throughput of the fan in response to a decrease in said pressure differential.
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Accused Products
Abstract
A powered respirator comprises a motor-driven fan unit drawing air through an upstream filter for delivery to a facepiece. Operation of the fan motor is controlled in response to a differential pressure sensor tapped in across the fan unit so as to reduce the fan throughput in response to an increase in the pressure differential and to increase the fan throughput in response to a decrease in the pressure differential, and thereby match the delivery of air to the breathing demand of the wearer. The diaphragm or other pressure-responsive member of the sensor is isolated from unfiltered air and can therefore provide no leakage path for contaminants to the facepiece. In an alternative embodiment the positions of the fan and filter are reversed so that the fan is upstream of the filter, and similarly controlled in response to the differential pressure across the fan. In the latter arrangement any contaminant which could pass through the pressure sensor is removed by the downstream filter before delivery to the facepiece.
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Citations
13 Claims
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1. A breathing apparatus comprising:
- a motor-driven fan;
filter means connected to the fan for removing one or more unwanted components from air drawn into the apparatus from the external atmosphere by operation of the fan;
a breathing interface means connected to receive such filtered air;
a differential pressure sensor comprising a flexible pressure-responsive member so connected to the apparatus as to be exposed on its opposite sides respectively to the pressure within the apparatus downstream of at least a stage of said fan and the pressure within the apparatus upstream of at least said stage of said fan or atmospheric pressure, and whereby in the event of destruction of or permeability of said pressure-responsive member to a said unwanted component the connection of the pressure sensor provides no pathway from the external atmosphere to said breathing interface means which does not also include said filter means; and
control means for controlling the operation of the fan motor in response to said sensor whereby to reduce the throughput of the fan in response to an increase in the pressure differential sensed by the sensor and to increase the throughput of the fan in response to a decrease in said pressure differential. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- a motor-driven fan;
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11. A breathing apparatus comprising:
- a motor-driven fan;
filter means connected to the inlet of the fan for removing one or more unwanted components from air drawn into the apparatus from the external atmosphere by operation of the fan;
a facepiece connected to the outlet of the fan to receive such filtered air;
a differential pressure sensor comprising a flexible pressure-responsive member so connected to the apparatus as to be exposed on its opposite sides respectively to the pressure within the apparatus at the outlet of said fan and the pressure within the apparatus at the inlet of said fan, whereby in the event of destruction of or permeability of said pressure-responsive member to a said unwanted component the connection of the pressure sensor provides no pathway to the facepiece for air which has not already traversed said filter means; and
control means for controlling the operation of the fan motor in response to said sensor whereby to reduce the throughput of the fan in response to an increase in the pressure differential sensed by the sensor and to increase the throughput of the fan in response to a decrease in said pressure differential.
- a motor-driven fan;
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12. A breathing apparatus comprising:
- a motor-driven fan;
filter means connected to the outlet of the fan for removing one or more unwanted components from air drawn into the apparatus from the external atmosphere by operation of the fan;
a facepiece connected to the outlet of the filter means to receive such filtered air;
a differential pressure sensor comprising a flexible pressure-responsive member so connected to the apparatus as to be exposed or its opposite sides respectively to the pressure within the apparatus at the outlet of said fan and the pressure within the apparatus at the inlet of said fan, whereby in the event of destruction of or permeability of said pressure-responsive member to a said unwanted component the connection of the pressure sensor provides no pathway for air to the facepiece except one which also includes said filter means; and
control means for controlling the operation of the fan motor in response to said sensor whereby to reduce the throughput of the fan in response to an increase in the pressure differential sensed by the sensor and to increase the throughput of the fan in response to a decrease in said pressure differential.
- a motor-driven fan;
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13. A breathing apparatus comprising:
- a motor-driven fan;
filter means connected to the outlet of the fan for removing one or more unwanted components from air drawn into the apparatus from the external atmosphere by operation of the fan;
a facepiece connected to the outlet of the filter means to receive such filtered air;
a differential pressure sensor comprising a flexible pressure-responsive member so connected to the apparatus as to be exposed on its opposite sides respectively to the pressure within the apparatus at the outlet of said fan and atmospheric pressure, whereby in the event of destruction of or permeability of said pressure-responsive member to a said unwanted component the connection of the pressure sensor provides no pathway for air to the facepiece except one which also includes said filter means; and
control means for controlling the operation of the fan motor in response to said sensor whereby to reduce the throughput of the fan in response to an increase in the pressure differential sensed by the sensor and to increase the throughput of the fan in response to a decrease in said pressure differential.
- a motor-driven fan;
Specification