Abstract:
A container ( 10 ) used for sterilizing medical instruments and the like has a sealed filtered vent. A wall or a lid of the container has a vent area formed by a plurality of holes ( 12 ) that pass therethrough. The vent area is surrounded by a convex ridge ( 16 ) on an outside surface of the container, with a corresponding concave recess ( 26 ) on an opposing inside surface. A web of filter material ( 36 ) is sized and adapted to cover the vent area and overlie the concave recess. A cover plate ( 37 ) is generally planar, with a vent area formed by a plurality of holes ( 38 ) that pass through the cover plate. This vent area is surrounded by a convex ridge ( 43 ) that is sized and adapted to correspond to the concave recess of the sterilization container. An elastomeric gasket ( 127 ) with outwardly-projecting ridges is secured to at least the convex ridge of the cover plate. A means for mounting the cover plate over the vent area of the container secures the filter material between the container vent area and the cover plate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a non-provisional patent application of U.S. 62/041,928, filed on 26 Aug. 2014, and makes a claim of priority thereto. This application incorporates the &#39;928 provisional application by reference as if fully recited herein. 
     
    
     TECHNICAL FIELD 
       [0002]    The disclosed embodiments pertain to fittings for filtered vents in containers used to sterilize surgical instruments and supplies. 
       BACKGROUND 
       [0003]    Acute care facilities rely on rigid containers for the sterilization, handling and storage of surgical instrumentation and supplies. It is imperative that after sterilization, the sterile surgical instruments and supplies not be exposed to contaminates while still in the sterilization container. 
         [0004]    Rigid sterilization containers commonly have a filtered vent (or vents) in the lid or other part of the container consisting of a patterned group of small holes. The floor of the container may also have a vent (or vents) which usually mirrors the number, size and placement of the vent or vents in the lid. One example of this is seen in U.S. Pat. No. 6,319,481, to Banks. Typically, each vent will have a sheet filter that covers the vented area and is held in place by a locking filter cover. 
         [0005]    One commercially available sheet filter suitable for use with the present invention and with sterilization protocols is a 1.4 osy (ounces per square yard) basis weight SECURON SMS manufactured by BBA Non-Wovens. Other suitable sheet filters are also commercially available. These special filter materials are characterized by the property that they are porous at elevated temperatures to allow sterilization media to pass and non-porous at lower temperatures. 
         [0006]    Thus, the vent, with the filter element held in place by a filter cover, allows for the entry of the sterilizing media and exit of the displaced atmosphere during the sterilization cycle. Following sterilization, the filter provides a bacterial barrier to protect the sterile integrity of the contents during storage and transport. 
         [0007]    As the sterilizing media is introduced into the sealed container, condensation can form and collect inside the container. Retained moisture in the form of condensation may be a by-product of either steam autoclaving or alternative low temperature sterilization methods. 
         [0008]    In addition to steam autoclaving, “flash” processing is a commonly used method of rapid steam sterilization. Since “flash” steam sterilization protocols have either a limited drying cycle or none at all, retained moisture is a persistent condition. Since bacteria have no form of self-propulsion or locomotion, they need fluid pathways or small particles as a vehicle or conduit for their movement and/or dispersal. 
         [0009]    Whenever there is retained moisture and the floor of a container is vented, the bacterial barrier properties of the filter assembly may be immediately compromised when exposed to a non-sterile atmosphere, while still at an elevated temperature (e.g., when the sterilization container is removed from the sterilization chamber). 
         [0010]    This situation is of special concern when retained moisture is present and the containers are handled, stored or transported while they are still hot. Containers with vented bottoms are at particular risk of contamination due to the occurrence of undetected leaking of fluid around (or through) the vents when the contents are assumed to be sterile. 
         [0011]    Consequently, rigid sterilization containers that do not form a fluid-proof seal, as well as a particulate seal, around the filtered vents are seriously limited and may be inappropriate for the multiple sterilization methods utilized by acute care facilities. 
         [0012]    Seals currently used for filter vents for sterilization containers are unprotected and subject to damage, which can form fluid pathways which compromise their integrity, making the containers unsafe for multiple uses. Improving the seal quality is a continuing goal in this art. 
       SUMMARY 
       [0013]    This and other objectives are met by a seal as described in more detail in the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    A better understanding of the inventive concept and the differences from the best known prior art will be achieved by reference to the drawings filed herewith, wherein identical reference numerals are used to identify identical parts and wherein: 
           [0015]      FIG. 1  is a top perspective view of a prior art rigid sterilization container having a lid with a vent formed by a pattern of small holes, as taught in U.S. Pat. No. 7,595,032 to Banks; 
           [0016]      FIG. 2  is a perspective view of the underside of the removable lid of  FIG. 1  rigid sterilization container, as also taught in Banks &#39;032; 
           [0017]      FIG. 3  is an exploded view of a vent as seen in  FIG. 2  as modified by the inventive concept, with a sheet filter and a filter cover; 
           [0018]      FIG. 4  is a side sectional view as would be seen along line  4 - 4  of  FIG. 3  with the vent, sheet filter and filter cover as modified by the inventive concept, in an unassembled condition; and 
           [0019]      FIG. 5  is a side sectional view of  FIG. 3 ; as seen along line  4 - 4  of  FIG. 3  with the vent, sheet filter and filter cover as modified by the inventive concept in an assembled condition. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    It will be understood by those skilled in the art that the present invention can and should be able to be varied in dimension, depending, in part, on the shape and size of the ventilated area to be sealed. 
         [0021]    Further, the present invention may be applicable to a number of materials, including, but not limited to, plastic, metal or any combination thereof so long as the material is resistant to conditions imposed by sterilization methods. 
         [0022]    In addition, while the invention is described with reference to a vent in the lid of a container, it will be recognized by those skilled in the art that the invention is equally applicable to a vent in the bottom or side of a container and that vents of different geometric patterns than that illustrated are within the scope of the invention. 
         [0023]    Referring to  FIG. 1 , a common design for a sterilization container  10 , as taught in U.S. Pat. No. 7,595,032 to Banks (“Banks &#39;032”), includes a vent area defined by a group of small holes  12  in the generally planar outside surface  13  of a lid  14 . A convex ridge  16  in the lid  14  is provided. This convex ridge  16  can be formed by simply deforming the interior surface of the lid  14  so as to simultaneously form both a concave surface (reference number  26  in  FIG. 2 ) below the interior surface and the convex ridge  16  above the exterior surface  13 . 
         [0024]    This bend, as will be seen in further views, provides a concave surface on the opposite side of the lid  14 . On the outside surface  13  of the lid  14 , the ridge  16  puts a delimiting border around the vent area and protects a filter (not seen in  FIG. 1 ), held in place on the opposite side of the lid, by preventing objects placed on top of the lid from protruding into holes  12 . It will be understood that the container body  18  and a locking means  20  for holding the container body and lid  14  together are conventional and do not require any further description. Although all structures seen in  FIG. 1  are according to the prior art, none of the structures are changed in implementing the inventive concept, as will be described. 
         [0025]    Referring to  FIG. 2 , which also reflects the prior art as established by Banks &#39;032, the sterilization container lid  14  is shown removed from the container and with the container lid inverted from the position of  FIG. 1 . The sterilization container lid  14  has an interior surface  21 , which is the “opposite” surface relative to outside surface  13  of  FIG. 1 . The vent area of  FIG. 1  is seen in  FIG. 2  as a surface  23  characterized by a plurality of holes  12  that pass entirely through the lid material. In this manner, sterilization media (such as steam) can pass into the interior of the container from the exterior. To this extent, it is notable that the vent structures being described here are not limited to being on the lid  14  of the container. The vent structures providing the inventive concept can be placed any surface of the container having sufficient area to accommodate them, especially the bottom of the container. Although vent  23  is illustrated as a pattern of holes  12  forming a generally square shape, vent  23  could just as well be a plurality of holes forming a rectangular, circular or some other shape, although a square or rectangular arrangement may have advantages. Likewise, although the holes are shown in a so-called “triangular” pitch, they could just as easily be arranged in a “square” pitch and still work with the claimed inventive concept. 
         [0026]    Surrounding the vent  23  on the interior surface  21  is the concave surface  26  that is referred to above as being opposite to, and, indeed, the result of convex ridge  16 . Also noted in  FIG. 2  are posts  39 , four of which are shown arranged around a perimeter defined by concave surface  26 . These posts  39  function to hold a filter (not shown in  FIG. 2 ) over the vent  23  on this interior surface  21  of the container, as will now be described. 
         [0027]    Attention is now directed to  FIGS. 3 through 5 , all of which are drawn from the teachings of the prior art Banks &#39;032 patent, but which incorporate the teachings of the inventive concept.  FIG. 3  is an exploded view that shows three distinct parts: the vent  23  and its surroundings on the sterilization container, a filter  36  and a filter cover  37 , which holds the filter in registration on the vent.  FIG. 4  is a side section view, taken along line  4 - 4  in  FIG. 2 , of the same three distinct parts, in an unassembled condition.  FIG. 5  shows the same view as  FIG. 4 , but in an assembled condition. Be mindful that  FIGS. 3 to 5  demonstrate the inventive concept and not the prior art. 
         [0028]    Working from the bottom up in  FIGS. 3 , the vent  23  with holes  12  and the posts  39  will be immediately recognized. However, where the Banks &#39;032 patent would show the vent  23  surrounded by a concave surface (reference number  26  from  FIG. 2 ) filled with a gasket, formed of a material having a soft DUROMETER rating, that is bonded into the concave surface, the gasket is not visible in  FIG. 3 , but it will be seen in an modified form as gasket  27  in  FIGS. 4 and 5 . This gasket  27  is preferably constructed of a temperature-tolerant material, such as silicone. The Banks &#39;032 patent specifically teaches that, regardless of the geometry, the gasket  27  is in contact with substantially all of the surface of concave surface  26  and is wholly within the recess  26  so as not to extend above the planar surface  21  of lid  14 , as is clearly seen in  FIG. 5  (of both this application and Banks &#39;032). 
         [0029]    The second part shown in  FIG. 3  is the sheet filter  36 , which overlays the vent  23  at the interior surface  21 . The sheet filter  36  is of sufficient width and length dimensions to lie upon not only the vent  23 , but also the concave surface  26 , preferably extending beyond the concave surface, thereby providing a good seal. To assist this, it would be known in this art to locate the posts  39  back from the concave surface  26 . 
         [0030]    The third part depicted in  FIG. 3  is the generally planar filter cover  37  which has a pattern of cover holes  38 . As is further seen in  FIGS. 4 and 5 , these cover holes  38  are typically offset from vent holes  12  when filter cover  37  is mounted and locked in position by posts  39  and a locking mechanism  40  (seen only in  FIGS. 4 and 5 ). Mechanisms  40  for locking a filter cover  37  to a vent  23  using slots or aligning posts such as posts  39  and establishing positive pressure on the cover against the vent are well known in the art and therefore require no further description, although Banks &#39;032 provides sufficient teaching. 
         [0031]    In addition to the vent holes  38 ,  FIG. 3  shows that filter cover  37  has a concave or recessed surface  41  on the surface  42  of the filter cover that faces into the interior of the sterilization container, that is, the upper surface of  FIG. 3 . 
         [0032]    Keeping in mind that  FIGS. 4 and 5  still reflect the inventive concept and not the prior art of the Banks &#39;032 patent, it is noted that the vent ridge  16  extends above (the lid  14  is illustrated upside-down) the plane of the exterior surface  13  of lid  14  and surrounds the vent  23 . In the preferred embodiment, the vent ridge  16  is the other side of the vent recess  26 , although they could be separately formed. In either case, the recess and ridge co-act to protect the vent  23  from damage that could cause a breach of the seal. 
         [0033]    In addition to the concave or recess surface  41  that surrounds cover holes  38  on side  42  of the filter cover  37 ,  FIGS. 4 and 5  show that there is a cover ridge  43  on opposite side  44 , the cover ridge surrounding the cover holes. The cover recess  41  and the cover ridge  43  can be formed as opposite sides of each other or separately. 
         [0034]    As best seen in  FIG. 5 , when the vent cover  37  is locked in position over the vent  23  by a filter cover mounting and locking mechanism  39  and  40  with a sheet filter  36  therebetween (the sheet filter being sized to extend over and cover the vent recess), the cover ridge  43 , as assisted by gasket  127  is forced against vent recess  26  with a positive pressure, causing filter  36  and gasket  127  to be compressed together between lid  14  and cover  37 , establishing a fluid-tight seal surrounding the vent  23  and cover holes  38 . 
         [0035]    As seen in  FIG. 5 , and even though the recess  26  and ridge  43  may be approximately equal in size, the filter  36  and the gasket  127  cause a space  46  to be established therebetween when the cover  37  is fully engaged. This space, which is greater than the thickness of filter  36 , plays an essential role in the movement of sterilization media through the vent  23 . 
         [0036]    Typically, during a sterilization cycle, sterilizing media enters the interior of the container  10  via the vent  23 , through the sheet filter  36  which is disposed between the lid  14  and filter cover  37 , while displaced atmosphere exits the same or another filtered vent. Any moisture formed in the sterilization container (not shown) is prevented from escaping the seal surrounding the vent and cover holes  38 . Equally important, any fluid on the outside of the container near a vent is prevented from entering the container. 
         [0037]    In the prior art, Banks &#39;032 teaches that it is important, as seen in  FIGS. 4 and 5 , the provide a protected location, such as recess  26  for gasket  27 . While this reduces the possibility of damage to the gasket, it also has the effect of reducing the surface area available for providing the sealing contact between the gasket  27  and the sheet filter  36 . It also places the gasket  27  on either the lid  14  or on a surface of the container body  18 . Either of these pieces will be at least as costly to replace as the vent cover  37 . 
         [0038]    It is useful at this point to discuss gasket  127  of the inventive concept. This A gasket  127  is at least placed atop ridge  43 . and, in many embodiments, it can extend out onto This gasket  127  differs significantly from the gasket  27  of the Banks &#39;032 prior art patent. First, it is placed atop ridge  43  and is not in any was associated with the recess  26  in lid  14 . Second, and because it is atop the ridge  43 , the outwardly facing surface  128  of the gasket  127  is convex and not concave. Third, and while Banks &#39;032 contains no express teachings about the surface of gasket  27  that would be in contact with sheet filter  36 , the outwardly facing surface  128  of gasket  127  preferably has one or more ridges  129  that extend outwardly, in a generally radial direction relative to the convex curvature if the surface  128 . These ridges  129  are best viewed in  FIG. 4 . These ridges  129  allow for greater purchase of the sheet filter  36  when the filter cover is fixed to the lid or container body at a vent  23  using fixing means already described. Particularly, the ridges  129  can deform and a pair of the ridges can capture a portion of the filter between them. A fourth difference is that the gasket  127  may be provided with an inner and an outer lip that can extend onto surface  44  as the gasket is positioned on ridge  43 . And, of course, gasket  127  can be bonded into place on ridge  43 , in which case the respective lips provide an additional amount of surface area for the bonding. 
         [0039]    These differences, when viewed as a whole, will be seen to provide the gasket  127  and the filter cover  37  with a significantly different and unexpectedly better operation. 
         [0040]    Of course, various changes, modifications and alterations in the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope thereof. 
         [0041]    As such, it is intended that the present invention only be limited by the terms of the appended claims.