Chemical apparatus and process disinfecting – deodorizing – preser – Physical type apparatus – Apparatus for treating solid article or material with fluid...
Reexamination Certificate
1998-11-03
2001-07-24
Warden, Sr., Robert J. (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Physical type apparatus
Apparatus for treating solid article or material with fluid...
C049S501000, C049S504000, C422S040000, C422S276000, C422S277000, C422S295000
Reexamination Certificate
active
06264901
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the sterilization arts. It finds particular application in connection with a sliding sterilizer door for sealing the opening to a sterilization chamber, and will be described with particular reference thereto. It should be appreciated, however, that the invention is also applicable to a variety of doors which are subject to thermal and mechanical stresses during their operation.
Steam sterilizers generally operate over a range of internal temperatures and pressures. The temperature and pressure within the sterilizer are varied as the sterilization cycle progresses. To withstand the fluctuating pressures, sterilizer doors are generally constructed from a solid metal plate. For additional strength, a supporting structure may be welded to an exterior surface of the plate.
For economic reasons, it is desirable for the door plate and the supporting structure to be formed from different materials. The doorplate is generally formed from a material which is both relatively strong and resistant to the chemical conditions of the sterilizer, such as stainless steel. The supporting structure may be formed from a material chosen solely for its strength as it need not be resistant to chemical degradation. The different materials used for the plate and the supporting structure frequently have different coefficients of expansion.
The temperature gradients in the sterilizer cause thermo-mechanical stresses to develop in the door. When heated, the different materials of the door expand to different extents. For larger doors, such as those used in walk-in steam sterilizers, such relative expansions are magnified, and tend to cause distortion of the door. The thermal distortion can hinder door operation during opening and closing and lower the service life of the door through fatigue of the materials.
One way to overcome the problem in larger doors is to use similar materials for both the door plate and supporting structure. However, this prevents use of the most economical mix of materials for construction of the door.
The present invention provides for a new and improved sterilizer door which overcomes the above-referenced problems and others.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a walk-in steam microbial decontamination apparatus is provided. The apparatus includes a chamber for receiving items to be microbially decontaminated. The chamber has an opening. A door selectively seals the opening. The door includes a plate sized to cover the opening, a framework for providing the door with structural strength, and a floating connection which connects the framework to an exterior surface of the plate such that the framework and the plate are free to expand and contract separately in response to a change in temperature.
In accordance with another aspect of the present invention, a door for a sterilizer is provided. The door includes a plate sized to cover an opening in the sterilizer, a framework for providing the door with structural strength, and a floating connection which connects the framework to an exterior surface of the plate such that the framework and the plate are free to expand and contract separately in response to a change in temperature.
In accordance with yet another aspect of the present invention, a method for selectively sealing an opening in a steam cabinet is provided. The method includes connecting a framework to an exterior surface of a plate with floating connections such that the framework and the plate are free to expand and contract independently in response to changes in temperature, the plate being sized to seal the opening. The method further includes sealing an interior surface of the plate to the cabinet around the opening and selectively holding the framework adjacent an exterior surface of the plate to prevent the plate from buckling outward in response to steam pressure in the cabinet.
One advantage of the present invention is that it prevents thermal distortion of the door.
Another advantage of the present invention is that the door plate and the support structure may be made of different materials having different coefficients of thermal expansion.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.
REFERENCES:
patent: 4590710 (1986-05-01), Newland
patent: 5146713 (1992-09-01), Grafius
patent: 5195790 (1993-03-01), Bulko et al.
patent: 5237777 (1993-08-01), Houston et al.
patent: 5249392 (1993-10-01), Houston et al.
patent: 5386674 (1995-02-01), Sfirakis et al.
patent: 5566508 (1996-10-01), Houston
patent: 6017105 (2000-01-01), Goughnour et al.
Fay Sharpe Fagan Minnich & McKee LLP
Soubra Imad
Steris Corporation
Warden, Sr. Robert J.
LandOfFree
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