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ACM 150
Visual check of the gas cell and FTIR optics
With the gas cell in place, visually examine the internal mirrors for any degradation of
the highly reflective surfaces, which includes:
•
pitting of the mirror surfaces
•
flaking-off of the mirror coating
•
coating of dust or chemicals
•
water spots or a tarnished appearance
Take a flashlight at an angle to check the mirrors more thoroughly. Examine the pair
of ZnSe windows for the same general problems. If you see any of these problems,
the gas cell should be removed and cleaned and the windows replaced.
You may not be able to see a chemical coating that absorbs infrared radiation and
lowers the throughput and, subsequently, the infrared signal at the detector. Perhaps
the signal is adequate but the noise may be too high, resulting in a poor S/N. Try
cleaning the gas cell and replacing the windows. Replace the gas cell if cleaning it
does not resolve the problem.
Check the transfer optics (gas cell's external mirrors) for dust accumulation or
tarnishing of the mirror finish. If you find dusty or tarnished mirrors, then also inspect
the external mirrors and window on the FTIR optics bench. These mirrors can be
cleaned.
Replacing the gas cell
Try cleaning the gas cell to remove dust, spots or chemical coating. If cleaning does
not correct the condition or if you see that the mirror coating is pitting, tarnished or
flaking-off, replace the gas cell.
Servicing the line leak test
This applies only if your ACM 150 utilizes the optional Line Leak Test. There are
no scheduled services. This daily test will generate a Service Status message and
identify any sample point(s) failing the test. If you experience any failures, isolate and
correct the problem following
Servicing the Desiccant Module
Check the service procedure document for details.
The desiccant module protects the bench from the effects of humidity and helps to
keep the internal optics of the bench warm. The desiccant module has an indicator
that has 4 numbers (20, 30, 40, 50) printed on a blue background. The color of the
background turns to white when the humidity inside the bench exceeds the level
indicated by the numbers. Replace the desiccant module every 12 months or when
indicator exceeds 30%.
Line leak tests
(optional).
125
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