Kurt J. Lesker 979 Series, Operation And Maintenance Manual

Page: 41 / 54

Series 979 ATV Transducer 41
Leak Detection
Its inherent sensitivity to gas type makes the 979 ATV Transducer useful for
detecting leaks at rates greater than 10
-4
std cc/sec of helium. It is a useful
complement to a mass spectrometer leak detector, which locates smaller
leaks.
Probe the suspected leak areas with a gas that is different from that of the
system gas. Helium is suitable for probing a system pumping air or nitrogen.
1. Pump your vacuum system to a base pressure.
2. Slowly and methodically probe with a small amount of the tracer gas
(helium).
3. Note the pressure reading.
The pressure will rise or fall, depending upon the thermal conductivity of
the probe gas relative to the system gas. The largest change in the value
indicates the probe gas is nearest the leak location.
4. Repeat the test to confirm.