Headspace modification method for removal of vacuum pressure

Abstract

To modify the headspace in a container to remove vacuum pressure, a container has a seal or cap which may provide a temporary opening into the container which is sealable under compression to provide a controlled raising of the internal pressure as the heated contents of the container cools. A sealing chamber ( 84 ) may enable the introduction of a fluid into the headspace ( 23 b ) to force the fluid level ( 40 ) lower. Other methods and apparatus are described.

We claim: 
     
         1 . A method for applying a cap to a finish of a filled plastic bottle comprising the steps of:
 positioning a chamber containing an apparatus holding a cap over the finish of the bottle so that a lower edge of the chamber s connected to a sealing ring;   pressing the sealing ring to a surface of known dimension on the bottle;   pressurizing the chamber and bottle interior with a volume of gas or vapor;   moving the holding apparatus and cap within the chamber relative to the finish of the bottle to seal the gas or vapor within the bottle;   releasing the pressure within the chamber; and   removing the sealing ring from the surface of known dimension.   
     
     
         2 . The method of  claim 1 , wherein the pressing step comprises engaging an outer surface of a support ring on the bottle with the sealing ring having an inner surface. 
     
     
         3 . The method of  claim 1 , wherein the step of moving the holding apparatus and cap comprises rotating the holding apparatus and cap while moving the holding apparatus and cap downward relative to the chamber. 
     
     
         4 . The method of  claim 1 , wherein the step of removing the sealing ring is preceded by releasing the cap from the holding apparatus. 
     
     
         5 . The method of  claim 1 , wherein the step of removing the sealing ring is followed by moving at least one of the sealing ring and bottle relative to each other by a distance sufficient to position the sealing ring on a second bottle and supplying a second cap to be applied to the second bottle to the holding apparatus.