Air Leaks - Agilent Technologies 7250 Troubleshooting And Maintenance Manual

2 General Troubleshooting

Air Leaks

Air leaks are a problem for any instrument that requires a vacuum to operate.
Leaks are generally caused by vacuum seals that are damaged or not fastened
correctly. Symptoms of leaks include:
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Leaks can occur in either the GC or the MS. The most likely point for an air leak is
a seal you recently opened.
In the GC, most leaks occur in:
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Leaks can occur in many more places in the MS:
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7250 Accurate-Mass Q-TOF Troubleshooting and Maintenance Manual
Higher than normal analyzer chamber pressure or foreline pressure
Higher than normal background
Peaks characteristic of air (m/z 18, 28, 32, and 44 or m/z 14 and 16)
Poor sensitivity
Low relative abundance of m/z 502 (this varies with the tune program used)
GC inlet septum
GC inlet column nut
Broken or cracked capillary column
GC/MS interface column nut
Side plate O-rings (all the way around)
Calibration valve
GC/MS interface O-ring (where the interface attaches to the analyzer
chamber)
End plate O-ring
Turbo pump O-rings
Collision cell cover O-ring
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