Abstract:
A closure and method of assembly for sample vials comprising a cap and a septum with the septum having a plurality of radially extending protrusions for retentive engagement with the cap to retain the septum and annular disk within the cap during positioning of the closure on the sample vial.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention relates to sample vials and more particularly to a closure and method of assembly for a sample vial having particular utility in gas chromatography. 
     Closures for sample bottles such as those used for feeding samples in a gas chromatograph according to the head space method generally comprise a pot shaped metal cap with a central aperture and a septum. The septum is essentially in the form of a circular disc adapted to cover the opening of the sample bottle and is positioned within the cap. The septum is a disc of elastic material like rubber which can be pierced by a hollow needle and which reseals itself when the hollow needle is removed. Such a closure is shown in the commonly assigned Kolb et al., U.S. Pat. No. 4,248,355 issued Feb. 3, 1981 entitled &#34;Closure for Sample Vials&#34; which is incorporated in its entirely herein by reference. 
     In practice, there is a problem with such closures in that the circular septa easily falls out of the cap when the closure is turned to place it on the sample bottle. This is particularly true if a resiliently elastic annular disc having a central aperture is inserted between the metal cap and the rubber disc such as shown in U.S. Pat. No. 4,248,355. 
     It is also known from U.S. Pat. No. 4,248,355 that the annular disc has a smaller diameter than the metal cap and is centered therein by rounded radial projections. These projections have only the function of centering and are neither configured nor suited to hold the annular disc in the cap and secure it against falling out. 
     It is an object of the present invention to provide a new and improved closure for sample vials. 
     It is a further object of the invention to provide a closure and method of assembly which affords expeditious mounting to the sample vial. 
     A further object of the invention is to provide a closure for sample vials which prevents the septum from falling out of the cap during positioning of the closure on the sample vial. 
     Another object of the invention is to provide such a closure wherein the septum is frictionally mounted within the cap to also retain the annular disk within the cap during positioning of the closure on the sample vial. 
     Another object of the invention is to provide a closure for sample vials having particular utility for introducing samples into a gas chromatograph utilizing the vapor space (head space) method. 
     Other objects will be in part obvious and in part pointed out more in detail hereinafter. 
     Accordingly, it has been found that the foregoing and related objects may be attained in a closure comprising a pot shaped cap having a top wall with a central access aperture and a side wall forming a recess and a septum for covering the opening of the vial being of generally circular shape with a plurality of radially extending protrusions configured for retentive engagement with the cap side wall to retain the septum within the recess. 
     The method of assembling a closure on a sample vial comprises positioning the septum within the cap, securing the septum within the cap prior to mounting the cap on the sample vial and mounting the cap to the sample vial to seal the opening with the septum. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is an enlarged exploded perspective view of a closure for sample bottles according to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Although specific forms of the present invention have been selected for illustration in the drawings, and the following description is drawn in specific terms for the purpose of describing these forms of the invention, the description is not intended to limit the scope of the invention which is defined in the appended claims. 
     Referring to FIG. 1, the closure of the present invention for sample bottle 11 generally comprises a cap 10, a disk 18 and a septum 24. The cap 10 is a pot-shaped metal cap 10 with a top wall 12 and a cylindrical rim or side wall 14. The metal cap 10 has a central aperture 16 in the top wall 12. 
     The annular disc 18 is located in the metal cap 10 between the septum 24 and the top 12 and has a central aperture 20 which is slightly smaller than the aperture 16 of the metal cap 10. The annular disc 18 is smaller in diameter than the inner diameter of the metal cap and has three rounded radial projections 22 angularly spaced by 120° for centering the annular disc 18 in the recess of the metal cap 10. 
     The septum 24 is essentially in the form of a circular disc for covering the opening (not illustrated) of a sample bottle 11 and is located in the metal cap 10. The septum 24 is made of butyl rubber or silicone rubber which is laminated with PTFE or aluminum. The septum has a plurality of radial protrusions 26 at its circumference configured to resiliently and frictionally engage the inner wall of the metal cap 10 when the closure is assembled to retain the septum in the metal cap. In the illustrated embodiment, the protrusions 26 comprise five equi-spaced protrusions extending radially outwardly from the circumference of the generally circular septum 24. By the retentive engagement of the projections 26 with the inner wall of the rim 14, the septum 24 is held in the metal cap 10 when the metal cap 10 is turned as illustrated to place it on the bottle. The septum 24 also holds the annular disc 18 between the septum and the top wall 12 of the metal cap 10 while the closure is placed on the bottle and the main body of the septum 24 is practically not deformed or distorted thereby. 
     In assembling the closure on the sample vial, the septum is positioned within the cap thereby securing the septum within the cap by the frictional engagement of the septum protrusions with the cap prior to mounting the cap on the sample bottle. Where an annular disc is utilized, the annular disc is positioned in the cap prior to securing the septum within the cap so as to retain the annular disc within the cap during the pacement of the cap on the sample vial for mounting. 
     As can be seen, the closure of the present invention prevents the septum from falling out of the cap during placement on the sample vial and, moreover, the frictional mounting of the septum in the cap also retains the annular disc therebetween during placement to facilitate mounting of the closure on the sample vial. 
     As will be apparent to persons skilled in the art, various modifications and adaptations of the structure and method above described will become readily apparent without departure from the spirit and scope of the invention, the scope of which is defined in the appended claims.