Vacuum Leak Test (VLT) Acceptance Criteria Importance in Pharma

Vacuum Leak Test for Autoclave:

To check for leakage in autoclaves, vacuum leak tests are conducted.
“The Chamber Integrity Test” is another name for the Vacuum Leak test.
In (Vacuum Leak test) VLT, a vacuum is initially applied within the chamber, followed by a wait for the vacuum to reach a predetermined set point, a holding period during which the vacuum is maintained, and finally, vacuum breakage.
Check the results afterward to see if the autoclave leakage was within the acceptable range.
According to the Health Technical Memorandum 2010 (HTM 2010) standards, VLT should be done once per week. (Full form of HTM is Health Technical Memorandum)
However, it is advisable to carry out VLT on a daily basis because this is a very important test that determines the chamber’s integrity.
There is a possibility that non-sterile air will enter the autoclave chamber if there is any leakage there or if the allowed amount of leakage is exceeded.
When a vacuum break occurs, air enters the chamber through a 0.22-micron filter that is situated on the autoclaves’ unloading side.
As sterile air passes through a 0.22-micron filter before entering the chamber, there is no danger of contamination.
However, if air entered the chamber through any other chamber connector than the filter, non-sterile air would enter and potentially contaminate the sterilized load.

As per Health Technical Memorandum 2010 (HTM 2010) standards Vacuum Leak Test (VLT) should be not more than (NMT) 1.3 mbar per minute.
However, some autoclave printouts specify the acceptance requirement as 0.013 bar without specifying whether the vacuum leakage limit is per minute or per 10 minutes. The technician can become confused as a result.
Here is the clarity:.

For example:

The result for vacuum leakage per 10 minutes is given by Z X 10 (Result for Leakage for 10 min.)
As per HTM 2010, the Acceptance criteria is NMT 1.3 mbar per minute
Some autoclave printouts suggest the results as 0.013 bar