Breathing equipment including a breathing hood to surround a wearer's head. An inner mask covers at least the wearer's mouth and nose. The equipment includes a breathing gas delivery conduit and structure to permit gas to pass from the hood to the mask. A check valve allows gas to pass from the mask to the surroundings when overpressure in the mask has reached a given value. The breathing gas is delivered to the hood and the gas passing structure permits gas to pass in both directions between the hood and the mask. The gas passing structure requires a lower overpressure in the mask for passage of gas from the mask to the hood than the pressure required for the check valve to release gas to the surroundings.
6957653 - Flushed-seal respirator - Owned by The United States of America as represented by the Secretary of the Department of Health and Human Services (Washington, DC)
Improved full-face, flushed-seal respirators are provided having a primary sealing element adjacent to a breathing space and a secondary sealing element. Exhaled air (i.e., clean air obtained by passage through a filtering element or elements) is passed from the breathing space into a flushing channel formed between the primary and secondary seals. If there is leakage in the primary seal, air from this flushing channel leaks into the breathing space rather than ambient air. Air within the flushing channel will predominately be air that has already passed through the filtering elements. The present invention provides, therefore, an inexpensive respirator which provides significantly more protection than conventional negative-pressure respirators.
The breathing system includes an elastic, non-porous body housed within an outer protective shell. The body terminates at its forward end in a protective cap and an air inlet passage and at its inner face in oral and nasal cavities. An air filter is disposed in the body and a mouthpiece, including a bite block, is provided for communicating filtered air into the individual's mouth. The bite block has converging surfaces for biasing the mask toward the individual's face when the individual bites down on the block. A hood attached to the mask surrounds the individual's head and receives exhaled air through exhalation ducts communicating between the mouthpiece and the hood.
An air-impermeable hood having first and second substantially airtight seals adapted to encircle a portion of a wearer's body below the head, typically the neck. Continuously exhaled air from the wearer of the hood is channeled between the first and second seals pressurizing a space there between creating a continuously pressurized purge zone to the introduction of ambient air into the hood. When the pressure in the purge zone exceeds the resistance of the second seal, air taking the path of least resistance flows out of the second seal. The effect is that exhaled air from the wearer creates a pressurized barrier against ambient air yet also prevents the accumulation of excess carbon dioxide and moisture within the ocular area.
A low noise exhalation port for a respiratory mask has a body including a proximal end operably connected to an internal area of the mask to vent carbon dioxide exhaled by a person from the mask, and a distal end. The venting device vents a gas out of the respiratory mask so as to substantially reduce inhalation by the person of the exhaled carbon dioxide. An exit passage portion is provided at the distal end and extends partially through the body and communicates with an exterior of the mask, the exit passage portion having a substantially regular cross-sectional area. An entrance passage portion is provided at the proximal end and extends partially through the body, the entrance passage portion communicating with an interior of the mask and further communicating with the exit passage portion, the entrance passage portion decreasing in cross-sectional area from the interior of the mask to the exit passage portion.
