Inficon 550-300A, Operating Manual

Page: 52 / 128

6-11
Operation
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For the external calibration, a separate test leak is required, which is mounted on the
chamber.
In Partial Flow mode, always perform an external calibration.
Sequence of calibration:
1
open the test leak or it opens automatically,
2 evacuate,
3
acknowledge steady-state signal when calibrate manually,
4 autotune (Calibration to maximum sensitivity),
5 vent to atmospheric pressure,
6 evacuate, after the measuring time is over, take the signal with open test leak,
7 vent to atmospheric pressure,:
8 close the test leak, evacuate, after the measuring time take the background signal,
9 vent to atmospheric pressure.
6.6.4 Calibration in Commander mode
During the calibration, the test gas supply is not enabled.
There are four different ways of calibration:
• Internal automatic
• Internal manual
• External automatic
• External manual
For the external calibration, a separate test leak is required, which is mounted on the
chamber.
The calibration procedure is the same as it is for the vacuum mode.
6.7 Machine factor
The machine factor takes into account that the Modul1000 is used in parallel with a
pumping system.(partial flow method).
Because in such a system configuration only a part of the leak gas flow reaches the
leak test device and is detected, first. the Modul1000 displays measured values on
the basis of the internal calibration which are smaller due to the partial flow ratio.
To avoid this, the machine factor can be saved in the software menu of the
Modul1000. Then, after an internal calibration, the measured leak rates are displayed
multiplied by the machine factor.
The machine factor can be estimated considering the Helium pumping speed of the
Modul1000 and of the external pump.
The measurement of an external test leak on a test sample is more accurate when it
is measured with and without an added external pump. The ratio of both results is the
machine factor.