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A vacuum leak test is used to determine the air-tight integrity of a pre-vacuum autoclave’s chamber and plumbing system.
A vacuum leak test is performed on an autoclave to check for any leakage. This test is also called a chamber integrity test.
The test exposes the autoclave’s plumbing and components to vacuum conditions and measures how much vacuum depth is lost over a given period of time.
The test checks for:
Potential pump malfunctions
Air leaks from the door gasket or pipe connections
The air tightness of the solenoid valves
The test is performed by:
Applying vacuum inside the chamber
Waiting for the vacuum to reach the set vacuum point
Holding the vacuum for the required time
Vacuum breakage occurs
The acceptance criteria for a leakage test is that the rate of pressure rise shall be not greater than 1.5 millibars per minute or 0.13 kilopascal per minute.
Acceptance criteria for VLT: As per HTM 2010 VLT should be not more than 1.3 mbar per minute. But in printouts of some autocalves the acceptance criteria mentioned is 0.013 bar and not showing whether this vacuum leakage limit is per minute or per 10 minute.
As per HTM 2010 guideline VLT should be performed on weekly basis. But it is good to perform VLT on daily basis becasue this is very critical test which define the integrity of the chamber.
If there is any leakage in the autoclave chamber or leakage is exceeding the limits it means there might be chance of entering non sterile air inside the chamber.
When vacuum break happens, air enter inside the chamber through the 0.22 micron filter which is located on the unloading side of the autoclaves.
There is no chance of contamination because sterile air enters inside the chamber after filtering through 0.22 micron filter. But if air enter inside the chamber from any other connectivity of the chamber other than the filter, non sterile air would enter inside the chamber and it could contaminate the sterilized load.
The UNI EN ISO 13060 standard requests the vacuum leak test.
Actual leakage:
Y-X=Z, if, as you stated, X is vacuum at hold time start and Y vacuum at hold time end. Otherwise you get a negative result, since Y always is larger or equal to X.
