Note:
AMI has taken many precautions for keeping the critical laser path clean during use in harsh gas
pipeline conditions. Our compact patented cellblock/sample system incorporates unique features;
including a membrane that blocks liquids and particulates found in the gas stream and bypassing them
prior to reaching the critical Herriott Measurement Cell.
It is important to remember that the analyzers bypass valve must be partially open, allowing approx.
1SCFH of gas to be bypassed, for liquids and particulates to properly drain.
Failure to do so will force the liquids through the membrane and contaminate the mirrors.
We highly recommend purchasing AMI’s complete optical cleaning Kit prior to disassembly and
cleaning the optical mirrors.
AMI’S Cleaning kit includes: a miniature rachet, 7/64 hex socket, 1/16” hex key wrench, 99%
Isopropyl alcohol with squeeze bottle, optical lens wipes, ¾” suave, 16oz. can of compressed nitrogen
and (2) new replacement o rings.
If liquid and debris from the pipeline do enter the analyzer, there are different actions that should be
taken depending on the severity of contamination.
Cleaning the Mirrors
Situation #1 – Heavy flooding contamination of analyzers due to water slug or other
upset condition.
Heavy contaminate loading in the analyzer can happen if the analyzer is not isolated during pigging
operations or other significant upset conditions. One sign of this is visible liquids or debris in the flow
meter of the analyzer. When this happens the small passages of the entire cell block have also been
saturated with liquids and they have been carried into the Herriot laser cell. As simple mirror cleaning
will not resolve this issue. If the unit is put back into service in this condition after a mirror cleaning it is
very likely more trapped contaminates will be forced onto the mirrors. If the analyzer has been heavily
flooded it should be returned to the factory for cleaning.
Situation #2 – Condensate and light oil build up on mirrors.
It is possible for a thin film or layer of oily residue accumulate on mirrors as the result of ambient heating
and cooling of the gas as wells as long term use. This condition would present itself as slight signal loss
over time. It is appropriate to utilize the mirror cleaning procedure to try to resolve this condition.
Situations Requiring Cleaning
38
