INFICON UL5000 Dry Helium Leak Detector - Manual (Page 77)

Calibration
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7 Calibration
7.1 Introduction
The UL5000 can be calibrated in two different ways:
• Internal calibration by means of a built-in leak standard.
• External calibration by means of an additional leak standard which then is
attached to the inlet port or the component under test.
During the calibration procedure the mass spectrometer is tuned to the maximum
helium signal and this signal is referred to the known leak rate of the internal or
external leak standard. Although the UL5000 is a very stable instrument a calibration
is recommended from time to time to make sure that ambient temperature changes
or dirt or other impacts don’t adulterate the measurements.
When the unit is used constantly the calibration should be performed at least once a
day. Otherwise the frequency of calibration depends on the frequency of use.
Notice: To get an optimized calibration the machine has to warm up at least 20
minutes before use .
Test leaks for calibration should not have a range lower than 1×10
-9
mbar l/s to
ensure a stable calibration signal.
7.2 The calibration routines
There are 3 ways to get into the calibration routine:
• In Stand-by mode (i.e. at the end of the run-up routine or after pressing the STOP
Button ) the calibration function can be initiated with CAL (Soft Key no. 5).
• Also in measurement mode the calibration routine can be started by pressing CAL
(Soft Key no. 5).
• In the main menu the calibration again can be started with CAL (Soft Key no. 5).
A calibration may be terminated at any time by pressing the STOP Button or using
the Soft Key no. 1 (Cancel).
Once the calibration mode is activated the user must choose between an internal and
an external calibration. Please press the corresponding Soft Key.