a device for evaluating the efficacy of prevacuum steam sterilizers by separating , collecting and detecting the presence of air in association with the steam . the device includes a receptacle containing an adsorbent for directly separating air from steam without requiring a change of state , from gas to liquid , of the steam . during sterilizer evacuation , the interstices of the adsorbent and the device offer a challenge to air removal . the receptacle has a portal to provide communication with the sterilizer environment and a defined path for the steam to traverse , in a progressive manner , moving to the distal end of the receptacle . the adsorbent retains the moisture during sterilization . at the distal end of the column is an opening into an air collecting chamber . within this chamber is located an article that indicates the presence of air in the steam . the indicator can be chemical or biological , and indicates whether any air pockets existed which prevented complete contact between the steam and the indicator .