Bowie Dick test for Vacuum Sterilizers.

Bowie Dick test has been widely used in pharmaceutical industries for the vacuum sterilizers. This test was developed by J. H. Bowie and J. Dick. This test is perform to verify heat penetration inside the chamber. As we know that pressure and vacuum pluses are there in steam sterilizers. The purpose of pressure and vacuum pulse is to effectively remove air from the chamber because air is a bad conductor of heat and if air pockets are present inside the chamber then it would be very difficult to sterilize the load. Heat penetration can be checked by oberving class 2 chemical indicator sheet which is used for this test. If colour change of the indicator sheet is uniform then it means air has effectively removed from the chamber and no air pockets left inside the chamber during sterilization. But if colour change is not uniform then it means these pulses are not effective to remove all air and air pockets from the chamber. In the past time, bowie dick test was performed by using layer of towels having an indicator sheet inbetween the towels. These towels were placed over the drain point which would be considered as cold spot of the autoclave. But now a days this towel concept has been replaced by the bowie dick pack. Different companies provide different bowie dick test kit but the purpose of all these kits it to check heat penetration inside the load. As per HTM 2010 guideline, it is also called standard test pack. Total weight of the pack should be 7.0±0.7 kg and height of the pack should be 25 cm or 250 mm. This test has to be perfomed on daily basis as per HTM 2010 guideline.The basic principle of this test is that when we run the bowie dick cycle air is removed from the chamber and all air trapped inside the bowie dick pack which we place over the drain point of the autoclave. If air removal is effective than heat penetration will be proper and there will be unifrom colour change of the indicator sheet. And if air removal is not effective then colour change will not be uniform. There are different type of bowie dick test packs available in the market. For example one of them is a set of paper sheets in a pack and middle of these sheets there would be a chemical indicator sheet. To use this type of bowie dick pack just place the pack as such over the drain point, no need to maintain the weight and height of the pack. Another one is having a S.S holder which can hold a bunch of sheet and in the middle, indicator sheet would be there and that pack has to be placed over the drain point. This one provide the required pressure on the pack (weight) and required height is maintained by the SS holder.

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