INFICON 3000 Micro GC Gas Analyzer Operating Manual - Manual (Page 240)

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3000 Micro GC Operating Manual
9.2.1.1.3 Baseline Noise
Noise is a continuous rapid baseline fluctuation, broadening the baseline and
giving it a grasslike appearance. Noise is different than spiking. Spikes are isolated
rather than continuous events.
Some noise is inevitable with any detector. At low sensitivity it may not be
noticeable, but noise may appear when the sensitivity is increased.
Noise appears suddenly on a previously clean baseline
This may be due to:
 Recent changes made to the system
 Loose connections in the detector or its signal path
 Detector contamination
 Contaminated carrier gas
If a tank was recently replaced, re-connect the previous tank to see if the noise
decreases. If the new carrier gas is contaminated such that it saturates a trap,
changing to the old one may show little improvement until the traps are replaced or
regenerated. This problem is most common with nitrogen carrier gas.
It is a common practice for empty carrier gas cylinders to be refilled by the gas
dealer after a thorough purging procedure. Deal with a reliable gas supplier.
Noise gradually increases to an unacceptable level
This symptom indicates gradual buildup of the noise source, rather than an abrupt
change as discussed above.
9.2.1.1.4 Baseline Spiking
Spikes are isolated baseline disturbances and usually appear as sudden large
upscale movements. If these spikes are accompanied by noise, address the noise
problem first, since spiking may disappear at the same time.
If spikes appear whenever a run is in progress, the cause is almost always
electronic in origin.
Loose connections are most likely the cause of spikes. Check all accessible cable
connections.
Make sure there is no external interference from local radio transmission
equipment.