Surgery – Respiratory method or device – Face mask covering a breathing passage
Reexamination Certificate
2000-09-01
2002-04-16
Weiss, John G. (Department: 3761)
Surgery
Respiratory method or device
Face mask covering a breathing passage
C128S201220, C128S201230, C128S201290, C128S205270, C128S205290, C128S206120, C128S206160, C128S206210, C128S206230, C128S206280, C002S202000, C002S413000, C002SDIG001, C002SDIG003, C002SDIG001
Reexamination Certificate
active
06371116
ABSTRACT:
FIELD OF INVENTION
The present invention relates generally to respiratory protective devices and more particularly, to an exhaled air pressured hood enclosure.
BACKGROUND OF THE INVENTION
Respiratory protective hoods benefit from positive air pressure within the hood to keep out contaminated, ambient air. This plenum provides a substantial level of protection should the protective enclosure be temporarily compromised. A significant danger exists when wearers of respiratory hoods breathe in air within the hood that may introduce harmful contaminants into the hood. One solution to this problem is to utilize exhaled air to keep the hood inflated and pressurized thereby creating a plenum against the introduction of ambient air. However, with each breath of exhaled air, the wearer introduces additional carbon dioxide and humidity into the hood.
The air that enters the lungs contains approximately 21 percent oxygen and 0.04 percent carbon dioxide. By contrast, the air that leaves the lungs contains 14 percent oxygen and 4.40 percent carbon dioxide. Consequently, a high level of carbon dioxide may accumulate within the hood.
Humidity is a measure of the amount of water vapor in the air. The air's capacity to hold vapor is limited but increases dramatically as the air warms, roughly doubling for each temperature increase of 10° C. (18° F.). As the body is exhaling warm, moist air, the humidity within the hood becomes increasingly high. In combination with a high concentration of carbon dioxide, this results in the hood becoming uncomfortably hot. In addition, outward vision while wearing a protective hood is typically achieved through the use of a transparent material integrated into the hood in front of the eyes. By accumulating carbon dioxide and humidity within the hood, moisture accumulates on the transparent material thereby inhibiting outward vision.
Another drawback in the prior art is that even if the user properly exhales into the hood to create the plenum, air pressure may reduce over time that requires the user to continually monitor the plenum in the hood to be assured that sufficient positive air pressure exists.
Standard gas masks must be manufactured in many different sizes because the structure of the nose and mouth area varies widely in populations including children and adults. It is logistically impractical for an authority responding to an emergency involving a large population to transport and fit a conventional face sealing gas mask to the victims. Face sealing gas masks must accommodate the variations of individual faces which would require the responding authority to not only stock and transport an inordinate number of masks, but it would also requires the authority to take a significant amount of time to assign the correct mask to the individual. Further compounding this problem is the fact that conventional face sealing gas masks must be adjusted to the fit the wearer. Again, this consumes a significant amount of time that may not be available, particularly when a large number of victims need assistance at the same time. What is needed is a protective device that can be quickly donned, yet accommodate the varying physiological differences within a given population.
Hooded masks are generally secured around the circumference of the neck and benefit from enhanced protection of the head area. However, this circumference can vary widely in a population. Furthermore, belts, elastic bands and the like are often used to tighten the seal between the hood and the neck. This tightening is difficult and time-consuming to achieve in an emergency situation and the user may either make the seal too loose and not provide adequate protection or may make the seal too tight leading to an uncomfortable fit that presses against the arteries and veins in the neck.
Another problem in the prior art involves the speed of donning the protective hood and establishing a secure respiratory pathway. Some hood embodiments in the prior art require the user to exhale into the hood before engaging the air filtration system. This added step not only adds to the time in which the hood becomes effective, but also increases the level of training needed to operate the hood properly. In many applications, protective hoods are designed for use in high-stress, dangerous environments. Reducing the speed in which the hood becomes effective and reducing the training required for operating the hood is beneficial. Furthermore, protective hoods may be distributed to an untrained civilian population that may have little or no training in donning and operating the protective hoods correctly. Therefore, simplification of operation and speed of use again become advantageous.
An object of this invention is to provide an air purifying respirator hood that automatically creates a plenum around the head.
Another object of this invention is to reduce the amount of moisture and carbon dioxide within the ocular region of a hood inflated by the wearer's exhalation.
Another object of this invention is to increase the overall protection factor of an air purifying respirator hood by establishing one or more pressurized zones against the introduction of ambient air into the hood enclosure.
Another object of this invention is to provide a continuously pressurized hood without the need for an external air source.
Another object of this invention is to provide a protective respirator hood having a substantially universal fit.
Previous attempts have been made to provide a protective hood enclosure such as described in U.S. Pat. No. 5,495,847 to Hu ('847 patent); U.S. Pat. No. 5,411,017 to Wong ('017 patent); U.S. Pat. No. 4,870,959 to Reisman et al. ('959 patent); U.S. Pat. No. 5,186,165 to Swann ('165 patent); U.S. Pat. Nos. 3,935,861 and 3,680,555 to Warncke ('861 and '555 patents); all of which are incorporate herein by reference.
The '017 patent to Wong describes a protective enclosure having elastic collars on the top and bottom. The bottom collar is closed against the wearer's neck and the top collar is closed against the wearer's head. Once donned, ambient air trapped within the protective enclosure is breathed in providing three to five minutes of escape time. However, exhaled air is trapped within the protective enclosure thereby accumulating moisture and carbon dioxide within the enclosure.
The '847 patent to Hu describes a survival hood comprising a hood for the head and neck which has an inside pocket with at least one upward open space, and a gas generator put in the pocket inside the hood to release oxygen through a chemical reaction for breathing when it is bent inwards to break an inside chemical solution container. However, the hood does not provide a secure seal to the neck for protection against NBC agents.
The '959 patent to Reisman et al. describes a protective breathing mask comprising a fire-resistant stretchable material shaped as a hood for wearing over and enclosing the head. The hood is primarily designed to combat smoke inhalation and subsequently does not provide suitable filtration or barrier means to NBC agents. Furthermore, exhaled air is trapped within the protective enclosure thereby accumulating moisture and carbon dioxide within the enclosure.
The '165 patent to Swann describes a deployable hood and mouthpiece having an exhalation check valve to permit exhaled air to flow into the hood. However, the operation of the '165 patent continually introduces carbon dioxide and moisture into the hood enclosure, thereby fogging up outward visibility and causing the wearer discomfort.
The '555 patent to Warncke teaches that intermittent exhaled air is used to pressurize a purge zone around the protection zone and is vented to ambient as needed to avoid over-pressurization of said purge zone. No suggestion of any kind is made that such intermittent exhaled air should be admitted into said protection zone. Furthermore, the '555 patent provides no reservoir of stored pressure during periods of non-exhalation. According
Hopen Anton J.
Smith & Hopen , P.A.
Weiss John G.
Weiss, Jr. Joseph F.
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