Steam sterilization indicator

Abstract

A steam sterilization indicator for indicating both exposure to steam and sterilization is provided. The steam sterilization indicator includes a backing member. A tablet formed of a compound having a first melting point and second melting point which is lower that the first melting point, the second melting point being the melting point of the compound exposed to steam is also provided. A wick is affixed to the backing member adjacent to the tablet. A steam permeable material covers the tablet and the wick. Upon melting, the tablet material is absorbed by the wick. A handle is affixed to the backing member. One end of the handle includes a steam exposure indicator formed of a color changing ink which changes color in the presence of steam.

What is claimed is: 
     
       1. A steam sterilization indicator for . .use in.!. .Iadd.monitoring sterilization of .Iaddend.a fabric pack .Iadd.at a predetermined sterilization temperature .Iaddend.comprising: .Iadd.(a) an internal sterilization indicator to be disposed within the fabric pack comprising   a backing strip;   a tablet formed of a compound having a normal melting point greater than . .a.!. .Iadd.the .Iaddend.predetermined .Iadd.sterilization .Iaddend.temperature, said melting point being depressed below said predetermined .Iadd.sterilization .Iaddend.temperature by absorption of water into the compound when said compound is exposed to saturated steam at the predetermined .Iadd.sterilization .Iaddend.temperature, . .said predetermined temperature being below the normal melting point of the compound,.!. said tablet being mounted on said backing strip;   wicking means for absorbing the compound after melting of the tablet disposed on said backing strip, said wicking means having a first end positioned in intimate contact with said compound;   a transparent steam permeable membrane adhesively bonded to said backing strip and covering said tablet and said wicking means, said steam permeable membrane controlling the exposure of said tablet to steam; .Iadd.and   acceptance indicating means for determining, in cooperation with said wicking means and absorbed compound whether the internal sterilization indicator has been exposed to conditions of steam and temperature for a period of time sufficient to achieve sterilizing conditions within the fabric pack;   (b) .Iaddend.a handle having a first end . .and second end.!. affixed to said backing strip at said first end .Iadd.of said internal sterilization indicator.Iaddend., said handle being dimensioned to extend externally of said fabric pack when said . .backing strip.!. .Iadd.internal sterilization indicator .Iaddend.is disposed within said fabric pack.Iadd.; .Iaddend.and   .Iadd.(c) a .Iaddend.steam exposure . .indicating means.!. .Iadd.indicator .Iaddend.mounted on said handle at . .said.!. .Iadd.a .Iaddend.second end.Iadd., remote from said first end, .Iaddend.for indicating exposure of said steam sterilization indicator to steam . .and acceptance indicating means for determining, in cooperation with said wicking means and absorbed compound, whether said fabric pack has been sterilized.!..Iadd., wherein said steam exposure indicator provides a positive indication of exposure to steam in less time than is required for the internal sterilization indicator to provide a positive response at the predetermined sterilization temperature .   
     
     
       2. The steam sterilization indicator of claim 1, wherein said acceptance indicating means includes an indicating cover disposed over said steam permeable membrane having a window formed therein for allowing observation of said absorbed compound as said absorbed compound travels along said wicking means and further including an indicator for indicating whether said tablet has melted sufficiently to indicate sterilization of said fabric pack. 
     
     
       3. The steam sterilization indicator of claim 1, wherein said steam exposure indicating means includes a steam sensitive ink, said steam sensitive ink changing color upon exposure to said saturated steam for a predetermined temperature and time interval, said ink being disposed on said handle, a portion of said handle including said ink extending without said fabric pack. 
     
     
       4. A steam sterilization indicator for use in a fabric pack comprising: a backing strip:   a tablet formed of a compound having a normal melting point greater than a predetermined temperature, said normal melting point being depressed below said predetermined temperature by absorption of water into the compound when said compound is exposed to saturated steam at the predetermined temperature, said predetermined temperature being below the normal melting point of the compound, said tablet being mounted on said backing strip;   wicking means for absorbing the compound after melting of the tablet disposed on said backing strip, said wicking means having a first end positioned in intimate contact with said compound;   a transparent steam permeable membrane adhesively bonded to said backing strip and covering said tablet and said wicking means, said steam permeable membrane controlling the exposure of said tablet to steam;   a handle affixed to said backing strip, said handle being dimensioned to extend without said fabric pack when said backing strip is disposed within said fabric pack;   steam exposure means for indicating exposure of said steam sterilization indicator to saturated steam for a predetermined temperature and time period;   said steam exposure indicating means including a steam sensitive ink, said steam sensitive ink changing color upon exposure to said saturated steam for a predetermined temperature and time interval, said ink being disposed on said handle, a portion of said handle including said ink extending without said fabric pack; and   acceptance indicating means for determining in cooperation with said wicking means and absorbed compound, whether said fabric pack has been sterilized, said acceptance indicating means including an indicating cover disposed over said steam permeable membrane having a window formed therein for allowing observation of said absorbed compound as said absorbed compound travels along said wicking means and said indicating cover further including an indicator for indicating whether said tablet has melted sufficiently to indicate sterilization of said fabric pack.