990 CLD Autoline™ Leak Detector
DR
AFT 2/2/04
3-5
If the bar graph ZERO control is set such that none of the segments on the bar graph
illuminate, the corresponding UNDER scale LED illuminates. Adjust the ZERO control so
that one segment is lit (with no helium or leak present). If the OVER scale LED illuminates
(along the 50 bar graph segments), select a larger leak range.
Initial positioning of the SENSITIVITY switch, when tuning and calibrating, depends on the
test object leak size specification and the operating range of the device being used for
tuning. Table 3-1 on page 3-5 indicates the suggested positions of the SENS1TIVITY switch
under these conditions.
Example
If the anticipated test object leak rate specification is in the:
❑
10
−
4
cc/sec range, then a calibrated leak in the 10
−
4
, 10
−
5
, or 10
−
6
range, or a tuning
leak is appropriate.
❑
10
−
8
range then a calibrated leak with a range of 10
−
8
or 10
−
9
is appropriate.
NOTE
If a direct-reading measured leak value is required, changing
the position of the SENSITIVITY switch requires re-calibration.
Normally, adjusting the CALIBRATE control accomplishes this.
Table 3-1
Suggested Setting of SENSITIVITY Switch for Tuning
Range of Test
Object Leak
Specification
(cc/sec)
7
Calibrated Leak Selection
Position of
SENSITIVITY
Switch
Helium Reservoir Leak
Capillary Leak
Tuning Leak
10
−
8
10
−
7
10
−
5
10
−
4
0
−
4
x x x x LOW
0
−
5
x x x x x LOW
0
−
6
x x x x x HIGH
0
−
7
x x x x x HIGH
0
−
8
x
x
HIGH
0
−
9
x x
HIGH
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