INFICON T-Guard Leak Detection Sensor - Manual (Page 48)

46
Operation
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INFICON recommends this kind of set-up for Accumulation mode:
5.3.2 Carrier Gas Mode
In addition to the gas flow, which the T-Guard™ Leak Detection Sensor takes out of
a chamber, more air can be sucked through the chamber using a fan or a pump.
This additional gas flow quickly carries the helium from the leak to T-Guard™ Leak
Detection Sensor. This way of leak detection is called Carrier Gas mode.
In Carrier Gas mode, the T-Guard™ Leak Detection Sensor measures the helium
content in the gas stream for a certain time. The helium signal from the end of the
measurement will be used in order to calculate the leak rate.
Carrier Gas mode can be used to detect bigger leaks faster than in Accumulation
mode.
The Carrier Gas mode is very sensitive to fluctuations of the helium background. An
elevated helium background is usually not stable.
Fig. 6-9 Recommended settings for Accumulation mode
Item Description Item Description
1 Test sample 5 T-Guard™ Leak Detection Sensor
2 Testing chamber 6 Fore pump exhaust air far apart from the
chamber
3 Fan
4 Measuring line connected
to the chamber 7 Reference line
8 Buffer volume > 4 litres