HP 5973 MSD, Hardware Manual

Page: 70 / 122

70
Troubleshooting
$LUOHDNV
Air leaks
How do I know if I have an air leak?
Large
air leaks can be detected by vacuum symptoms: loud gurgling noise from the
foreline pump, inability of the turbo pump to reach 95% speed, or, in the case of
smaller leaks, high pressure readings on the high vacuum gauge controller.
Note that the mass flow controller is calibrated for methane, and the high vacuum
gauge controller is calibrated for helium, so these measurements are not accurate
in absolute terms, but are intended as a guide to typical observed readings. They
were taken with the following set of conditions:
Source temperature 250°C
Quad temperature 106°C
Interface temperature 320°C
Helium carrier gas flow 1ml/min
MFC (%) Pressure (Torr)
Methane Isobutane Ammonia
10 5.6
×
10
-5
6.5
×
10
-5
4.7
×
10
-5
15 7.7
×
10
-5
9.2
×
10
-5
6.7
×
10
-5
20 9.8
×
10
-5
1.2
×
10
-4
8.5
×
10
-5
25 1.2
×
10
-4
1.4
×
10
-4
1.0
×
10
-4
30 1.4
×
10
-4
1.8
×
10
-4
1.2
×
10
-4
35 1.6
×
10
-4
2.0
×
10
-4
1.4
×
10
-4
40 1.8
×
10
-4
2.3
×
10
-4
1.6
×
10
-4
45 2.0
×
10
-4
2.6
×
10
-4
1.9
×
10
-4
50 2.2
×
10
-4
3.0
×
10
-4
2.1
×
10
-4
60 2.7
×
10
-4
3.5
×
10
-4
2.5
×
10
-4