Ventilation – Workstation ventilator – Covered workbench chamber
Reexamination Certificate
2003-03-27
2004-11-23
Joyce, Harold (Department: 3749)
Ventilation
Workstation ventilator
Covered workbench chamber
C055S385200, C454S060000
Reexamination Certificate
active
06821200
ABSTRACT:
BACKGROUND OF THE INVENTION
1.1. Field of the Invention
The present invention relates to the fields of hazardous materials handling and anti-contamination hoods and cupboards.
2. Prior Art
Fume hoods and cupboards have been used for years to protect personnel from hazardous airborne fumes, aerosols, and particulates during procedures where these hazardous materials may be generated or used. Hoods designed to protect personnel from hazardous materials typically pull ambient air into the hood, and exhaust it either to the outside via a duct that carries it to a distant outlet point or, for portable units, back into the same room after the exhaust air has been filtered or otherwise treated to render it free of the hazardous materials. In this type of hood, the pressure within the hood is maintained slightly negative, so that all airflow is into the hood, so that hazardous materials cannot escape and be breathed by or deposited on personnel.
There are other, similar hoods, which are designed to protect the process being undertaken within it from contamination by personnel or by dust and other contaminants in the ambient air. In this latter type of hood, referred to herein as an anti-contamination hood, the airflow is in the opposite direction from the former. Air is filtered or otherwise treated before being passed into the hood, and the pressure within the hood is maintained slightly positive, so that only filtered air can enter the hood.
Typically, most of these hoods are expensive and difficult to clean after use. Furthermore, because of this difficulty of cleaning, simply servicing them can be difficult because they may have been contaminated in normal use. This difficulty of cleaning and servicing has become particularly an issue recently with the potential for chemical and biological terror attacks via the post office and other package delivery services. There is a need for a low-cost hood primarily made of materials that can be burned or incinerated if the hood becomes contaminated.
Disposable hoods have been described. U.S. Pat. No. 5,928,075 describes a design for a disposable hood. However, this design is primarily a semi-closed, limited-access, still-air box, which will fail to adequately protect personnel from airborne contaminants unless an air-drawing means is attached to draw air into the box, and a filter is provided to prevent any contaminants from exiting with the exhaust air from the air-drawing means. While such a fan and filter means is mentioned, the fan and filter described would be completely inadequate to prevent many types of hazardous contaminants from escaping the hood. Furthermore the design requires a front cover that partially occludes the front of the hood, to insure adequate containment of contaminants. It is extremely important in many applications that personnel using the hood be immediately aware that contaminants have been released into the interior of the hood, and an absolute, hermetic sealing means must be provided to insure that no contaminants can escape if the unit must be shipped or otherwise handled after contamination. U.S. Pat. No. 5,928,075 fails to address these issues. The present invention addresses all of these concerns and results in a hood applicable to a much larger number of applications than the hood taught in U.S. Pat. No. 5,928,07.
Of particular concern in disposable hoods used for protection of extremely high hazard contaminates is the efficiency of the filtering means protecting personnel, or preventing contamination of processes by microbes and other extremely small contaminants. U.S. Pat. No. 6,328,788 describes a unique filtering material that has significant advantages for these applications. A composite material comprised of a combination of dissimilar fibers, principally, polypropylene and polymethaphenylene isophatalamide fibers is described that results in a phenomenon called triboelecticity when air passes through the material. Triboelecticity is a static electric charge that forms on the fibers, which greatly increases the efficiency of filtration, with reduced occlusion of the airflow.
The purpose of the present invention is to simplify or eliminate issues of cleaning, servicing and disposal of either hazardous material handling, or anti-contamination types of hood, while providing a high level of safety.
BRIEF SUMMARY OF THE INVENTION
Hazardous materials handling and anti-contamination flow hoods are disclosed. These hoods are specifically designed for low cost production, so that, in the case of hazardous materials handling hoods, the entire unit, or substantial portions, can economically be disposed of if contaminated, or if either type of unit must be serviced. The invention further includes low-cost, high efficiency filters to further facilitate low cost. Means may be provided for some applications to assist personnel in quickly identifying the presence of hazardous contaminants, so that the unit can be immediately sealed.
Furthermore, the design provides built-in means for closing and/or sealing the unit so that no contamination can escape during and after the sealing process. Once sealed, the unit can be burned in an incinerator, or shipped economically to an analytical laboratory to determine the nature of the contamination if unknown, and burned afterwards.
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Chilcoat Edward Alan
Chilcoat Robert Talmadge
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