Outside-In Go-No-Go Testing
The component to be tested is connected to a vacuum pump and Leak Detector and evacuated. The part is held in a chamber or hood which is filled with a known Tracer Gas - typically Helium.
The system (Leak Detector) then monitors for the ingress, hence the term Outside-In, of Tracer Gas to the part indicating the presence of a leak. This type of test is easily automated and, time permitting, can be more sensitive than sniffing. It does not, however, pinpoint the site of a leak and assumes the component does not have any major leak that would prevent pump-down to operational vacuum.
