Inficon 540-200, Translation Of The Original Operating Instructions

Page: 56 / 90

6 | Operation INFICON
56 / 90 T-Guard2_Operating-instructions-jina85en1-13-(2009)
6.8 Helium contamination
The sensor is well protected from helium contamination. Every measurement cycle
begins with a GROSS measurement. The sensitivity of the sensor is limited during the
GROSS measurement. The subsequent FINE measurement is stopped immediately
when the following measurement value is reached:
• > 5 × trigger value 1, if trigger value 2 is not active
• > 5 × trigger value 2, if trigger value 2 is active
In addition, you can set limits for the helium contamination. The device stops the
measurement when they are reached, see Settings for the measurements [
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51]
If the sensor is then contaminated again, direct helium-free nitrogen or outside air to
the reference inlet. This cleans the sensor. The cleaning time depends on the helium
content of the supplied air and the degree of contamination.
Continuous
measurement
No trigger value can be set for the continuous measurement. You must therefore stop
the measurement yourself as soon as you see that the sensor current is too high. The
device switches automatically to the reference line as a last resort when the sensor
current is greater than 1  10
-8
A.
6.9 Standby
In standby, air is sucked through the reference line and the sensor is purged. This
preserves the sensor. Always select standby if no measurement is currently taking
place during a continuous measurement session but you do not want to switch the
device off.
► Select “Operating mode > Standby” in the main menu.
During an accumulation and a carrier gas measurement, the device automatically
goes into standby when not in use. The time taken to enter standby can be set.
► In the main menu, select “Settings > Measurement settings > Standby delay”.