Air Leaks - HP 5973 MSD Hardware Manual

 Troubleshooting
$LU OHDNV

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
Quad temperature
Interface temperature
Helium carrier gas flow
MFC (%) Pressure (Torr)
Methane
5.6 × 10
10
7.7 × 10
15
9.8 × 10
20
1.2 × 10
25
1.4 × 10
30
1.6 × 10
35
1.8 × 10
40
2.0 × 10
45
2.2 × 10
50
2.7 × 10
60
70
250°C
106°C
320°C
1ml/min
Isobutane
6.5 × 10
-5 -5
9.2 × 10
-5 -5
1.2 × 10
-5 -4
1.4 × 10
-4 -4
1.8 × 10
-4 -4
2.0 × 10
-4 -4
2.3 × 10
-4 -4
2.6 × 10
-4 -4
3.0 × 10
-4 -4
3.5 × 10
-4 -4
Ammonia
4.7 × 10
-5
6.7 × 10
-5
8.5 × 10
-5
1.0 × 10
-4
1.2 × 10
-4
1.4 × 10
-4
1.6 × 10
-4
1.9 × 10
-4
2.1 × 10
-4
2.5 × 10
-4