Honeywell ACM 150 Manual To Installation, Operation, And Maintenance page 123

ACM 150
years, before problems develop in normal use. The valves contacting the sampled
gas have Teflon bodies, which are resistant to both corrosion and the absorption
of acid gases. Nevertheless, any of these valves can fail in normal use. Use the
manual checks and tests,
instructions in
Tubing
When you disconnect any internal or external tube fitting from a valve or pump,
inspect the end of the tube and the tube fitting. Look for signs of corrosion, particles
and/or chemical coating. Replace tubes and fittings that show any of these signs.
Also, look for over-tight fittings that compress the tube diameter at the ferrules and
create a flow restriction. Replace the fitting and the ferrules.
Inspect internal tubing for any crimps, worn spots and splits, especially around the
fittings. Replace defective tubes.
NOTE
Compression tube fittings, e.g. Swagelok fittings, should be turned with a
wrench 1/4 turn past finger-tight. Avoid over-tightening the fittings.
Evaluating the FTIR optical path
The modulated infrared beam produced inside the FTIR analyzer (optics bench)
passes through windows, reflects off of mirrors and ultimately focuses onto a 2 mm
diameter detector. To get the best performance from the ACM 150 monitor, the path
through these optics must be clean and clear, and the optics must be in alignment.
Use this procedure to evaluate the condition of the optical path by examining, the
ZPD Value, the Signal-to-Noise Ratio and Spectral Balance. After completing these
three evaluations, proceed to
NOTE
These evaluations help determine if it is necessary to inspect and clean the gas
cell, adjust the gain and/or align the optics. If they indicate that everything is
OK, it can save unnecessary work and downtime.
ZPD value
Follow the instructions in
ZPD is a positive number for the Perkin Elmer bench. Typical readings are 50 to 2000.
The typical range for the Perkin Elmer ZPD with properly aligned and clean optics is
between 75 and 2000 when read in the Background mode, i.e. when the gas cell is
filled with nitrogen.
• If the 15 day trend is within the range of 75 and 2000 and if there are no
significant changes in the trend, the IR signal is adequate.
• If the 15 day trend is outside these limits and/or if you see a significant change
causing a signal degradation in the trend, it fails this evaluation.
NOTE
For more information about the ZPD value refer to
Cycle valve
Cycle valves.
Determining the next
ZPD trends
tests, identify any problems. Follow the service
step.
and look at the trend over the past 15 days.
ZPD value and
123
location.