VS Series Helium Mass Spectrometer Leak Detectors
B-4
DRAFT 4
/23/15
B.3.1 Vacuum Testing Method (Outside-in)
The part to be tested is evacuated with a separate pumping system for large volumes, or
with just the leak detector itself. When the appropriate cross over pressure has been
reached, the leak detector is valved-in or transfers into test and the part is tested using one of
the following methods:
B.3.1.1 Locating Leaks
To pinpoint t h e l o cation of the leak(s) (but not measure the total leakage rate), helium is
administered to the suspected leak sites of the part using a spray probe with an adjustable
flow (Figure B-3).
Figure B-3 Locating Leaks: Outside In
B.3.1.2 Measuring Leaks
To de t e r m i n e the total q u a n t ity o f leakage ( b u t not the number or location of leaks), the part
is connected to the leak detector and shrouded by a helium environment. This helium
environment can be contained in many methods ranging from a simple plastic bag to more
complex bell jar arrangements (Figure B-4).
Figure B-4 Measuring Leaks: Outside In
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