Inficon 550-300A, Operating Manual

Page: 63 / 128

Operation
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Commander Pressure Threshold
p_A initial leak test
Lowest pressure to which the unit under test may drop
; factory setting: 900 mbar
p_B evacuation pressure
Pressure to which the unit under test is evacuated
; factory setting: 40 mbar
p_C fill pressure
Pressure to which the unit under test is filled with helium
; factory setting: 2000 mbar
p_D depressurising pressure
Pressure to which the helium is released from the unit under test
; factory setting: 1100 mbar
p_E pressure fall threshold
Minimum permissible pressure of the unit under test during leakage rate measure-
ment
; factory setting: 1800 mbar
Main menu
o
Settings
o
Vacuum settings
o
Machine factor
After internal calibration, the machine factor considers the relation between the effec-
tive pumping speed of the Modul1000 and of the system pump stand in measuring
mode.
The machine factor takes into account that an additional external pumping system is
used.
Because internal calibration does not take into account the sharing of helium in
partial flow mode, all measured leak rate would be measured too small.
The measured leak rates are multiplied with the machine factor and the result is
displayed. This factor is only used for vacuum mode (not for sniff mode).
The machine factor can be estimated under consideration of both, the helium pump-
ing speed of the Modul1000 and the external pump.
The measurement of an external test leak on a unit under test is more accurate when
it is measured with and without an added external pump. The machine factor is
defined by the difference between the results.
The machine factor can also be used to correct the leak rate display referred to the
air equivalent. The machine factor for this correction is
3.7 x 10
-1
.
When the machine factor does not equal 1,this status will be displayed by „COR“.
Main menu
o
Settings
o
Vacuum settings
o
Leak rate internal test leak
The value of the internal test leak can be set here.