INFICON T-Guard Leak Detection Sensor - Manual (Page 65)

Operation
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Main menu
→ Info →
Cal Factor
This screen shows the actual calibration factor and its global limits. The calibration
factor should be near 1 for a good setting of the automatic times.
Possible values: 0.2 to 5.
Default setting: 1.
Service
This menu item is for authorized INFICON service personnel only.
Main menu
→ Access control →
Access to CAL function
Here, you can lock and unlock the access to the calibration function.
Change Menu PIN
Here, you can set or change a 4 digit PIN to prevent access to the menu via the
control unit. A Menu PIN of "0000" means, that no Menu PIN is assigned.
5.9 F.A.Q. - Frequently asked questions
Q: Why can the measurements not be reproduced?
A1: It is less possible to reproduce measurements when the T-Guard indicates
"moderate background" or "bad background".
Remedial measures: Decrease the background by checking the helium supply
for leaks. If possible, place the helium supply far away from the T-Guard.
Evacuate the test sample after the measurement in order to dispose of the
helium.
Purge the measurement chamber with ambient air. Carrier gas mode only works
if you have a constant pressure of 5 ppm of helium in the air.
A2: Measurements are less reproducible if the chamber has little slots or holes. A
calibration factor of 1.3 or more indicates that he chamber volume was entered
correctly.
A3: Measurements are less reproducible if the trigger level is a lot higher than the
measured leakage rate. The trigger level should be equal to the leakage rate to
be measured.
A4: Measurements are less reproducible if the measurement time was reduced too
much. This has the same effect as a trigger level that is too high.
A5: Measurements are less reproducible if the chamber fan is too weak. The fan
should circulate the chamber volume twice per second.
A6: Measurements are less reproducible if they are carried out in Only GROSS
mode. If this is the case, the T-Guard displays "Only GROSS" when changing the
trigger level.
Remedial measures: Avoid an Only GROSS measurement by using diluted
helium (and setting this) or by using a larger chamber.