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Ted Mooney, P.E. RET
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for Metal Finishing 1989-2025
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NOx Emissions from Titanium NDT Etching?
Part of the NDT flaw detection process for Titanium alloy jet turbine components requires a Macro-Etching process to examine anomalies at low magnification.
The etching process is Nitric Acid based at 500 g/litre at maximum
35C. My question is: under these conditions I have been told (by Scrubber Manufacturer) that one can expect NOx emissions in excess of
100 ppm.
I'm sorry but I am having trouble believing that NOx fumes even exist since HNO3 at 35C and Ti are very compatible. Am I missing something?
designer - Montreal, Quebec, Canada
March 27, 2009
It is not NO or NO2 that your scrubber manufacture is talking about it is actually nitric acid fume- HNO3. Nitric acid at that temperature and concentration has a high enough vapor pressure to emit a considerable amount of nitric acid fume. It doesn't matter what kind of parts or how many you process- it is just concentration and temperature related. Nitric acid fume requires a multiple-stage wet scrubber.
Jon Barrows, MSF, EHSSC
Independence, Missouri
April 22, 2009
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