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a (mostly) invisible difference between my civilian & military Fluke gear

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arcitech:

--- Quote from: tooki on October 30, 2022, 05:06:23 pm ---
--- Quote from: arcitech on October 30, 2022, 02:39:03 pm ---
--- Quote from: Fungus on October 30, 2022, 01:44:43 pm ---
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One memorable lesson I learned working in aerospace was around alumin(i)um oxidation -- it is certainly worth caring about in a variety of mission critical scenarios, such as those involving various altitude/temperature extremes, and likely also high salinity environments. Sure, it doesn't "rust" in the commonfolk sense of the term, but the mechE cautioning me as I cut holes into a vehicle of my own as I installed some electronics gear made it very clear to me (and I trusted him enough to feel like I didn't need to fact check): Al does in fact rust. It may not look like the popular definition of rust, and it may not spread like that sort of rust either, but apparently it's enough of a concern that, for some applications, any opportunity for (ongoing, not immediate) oxidation of Al warrants countermeasures.

--- End quote ---
Well… no. Rust specifically and exclusively means iron oxide, and only iron can oxidize to iron oxide. But aluminum does oxidize. (In other words: rusting is not a synonym for oxidation, it’s a very specific oxidation.)

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Thanks for rectifying what the better part of a decade has degraded.

An edit taking that correction into account, not up there, but just right here:
Al does in fact [oxidize]. It may not look like the [actual] definition of rust, and it may not spread like [actual] rust either, but apparently it's enough of a concern that, for some applications, any opportunity for (ongoing, not immediate) oxidation of Al warrants countermeasures.

I wonder then whether at sea this was in fact busy work, or warranted.



Chances are slim I guess of anyone sharing findings, let alone photos, of actual meters, but fingers are still crossed…

daisizhou:
Your FLUKE 27 looks like a civilian version, the military one should be 27/FM, and it's brown

CatalinaWOW:
arcitech has nailed it.  In the applications where most people encounter aluminum it is very corrosion resistant.  I have aluminum siding on some of my shops that is more than 40 years old, unpainted and looks like new.  But I live in a cool inland environment.  Negligible salt and whenever it is hot it is very dry.  I have been at beachside in hot environments where you can almost watch the progression of rust in ferrous materials and even aluminum frequently shows degradation over intervals much shorter than a decade.

Add to that the problems caused by dis-similar metals in contact with salty water and there is a definite need to protect even aluminum.  Warships are expensive and nations which operate them try to get many decades of service out of them.  Things that would not cause problems in a consumer product that is usually taken out of service in a decade or two are real issues for these machines.  The designers try to avoid contact between metals with different voltaic potential, but it is impossible to achieve this everywhere, so a moisture barrier paint is a good choice.

A quarter inch of paint may have been a bit of an exaggeration, but the number of 10 mil layers that can be applied in a 50 year service life is impressive.  Even when you think about the fact that chipping or scaling is part of the painting drill that keeps idle sailors hands out of trouble.

arcitech:

--- Quote from: daisizhou on October 31, 2022, 12:51:24 am ---Your FLUKE 27 looks like a civilian version, the military one should be 27/FM, and it's brown

--- End quote ---

The old ones are gray. The newer ones were not. The FM is indicated on the label affixed to the rear, and it came in a standard mil case of that vintage with the RF and HV probes.

Or I’m just wrong.

daisizhou:
I've been using this model as well, the point is that the military internals are RMS voltages and civilians are average.

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