INFICON UL1000 Helium leak detector - Manual (Page 88)

88
Calibration
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7 Calibration
7.1 Introduction
The UL1000 and UL1000 Fab 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 UL1000 and UL1000 Fab 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
The calibration routines can be started by pressing button CAL (Softkey 5) via 3
different locations:
• main menu
• Stand-by mode
• measurement mode
The access via Stand-by mode or measurement mode can possibly be not available.
(Refer to chapter
Access to CAL function ). In this case there will be no inscription on
the correspondingly Soft Key.
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.