Tracer Location Testing
This is similar to the Outside-In test except that the hood or chamber into which the evacuated part is positioned has been removed. The significant change is that an operator now probes around the part with a sprayer wand allowing trace gas to flow, selectively, around potential leak sites such as joints and fabrication seams.
As the wand passes a leak, small amounts of trace gas that enter the part are detected by the leak detector. In this way, the location of the leak may be pinpointed, with accuracy, if care is taken. This technique can be more sensitive than Sniffing but the operator must be wary of tracer gas drift which can be confusing. It would take much longer to test a complete part in this way than with an automated system. This technique is usually reserved for testing components which have failed a general Outside-In test. VTI Outside-In systems have a spray wand to allow quick checks on key joints to be made on-line by an intervening operator.
