More tetrabromoethane questions

[wxrocks]

I didn't get much on my last one -- but here's a different question regarding this chemical ...

I know this stuff reacts with active metals -- it says keep away from Mg, Brass and Aluminum -- but I am wondering if a hard coat anodizing on aluminum would prevent this reaction. Any ideas??

Eric

 

[Gokul43201]

It would definitely help. I suspect the primary corrosive element is the little bit of HBr in the vapor.

I'll look around a little bit and see if I have something among my bookmarks.

 

[wxrocks]

thanks

thanks for the reply -- and I hope you can find more info on this stuff. Its interesting how this simple chemical can be so nasty!

 

[Bystander]

Hit the fire codes, NFPR, and you might find something. Al plus alkyl halides (maybe minus F) make for impact sensitive situations. Never tracked down any details about mechanisms, weathered, anodized, bright Al surfaces, or any other pertinent details; aluminum oxide is an adsorbent surface far as alkyl halides go, anodized aluminum surfaces are microfissured (unless steamed, and still remain somewhat fissured), so the anodizing might actually aggravate the hazard.

My suspicion is that the primary reactive hazard is formation of AlX₃, or mixed AlOX --- given that NFPR has incident reports of detonations on "dry" Al surfaces that have been exposed to "perc," "trike," MeCl₂, and other chlorinated solvents, and from personal experience with the facility of "double replacement reactions" of MX with Al₂O₃, you might be a lot happier to run some very small scale tests in a hood before committing yourself to anything on a large scale.

 

[Gokul43201]

I didn't get much on my last one -- but here's a different question regarding this chemical ...

I know this stuff reacts with active metals -- it says keep away from Mg, Brass and Aluminum -- but I am wondering if a hard coat anodizing on aluminum would prevent this reaction. Any ideas??

Eric

Reading Bystander's post, I have to ask this: are you worried about corrosion from direct contact or exposure to vapor?

Also, Bystander, I've used methylene chloride on aluminum parts without too much trouble (mostly to dissolve an epoxy). So, what does NFPR mean by "dry" aluminum?

 

[Bystander]

"Dry" far as the "incident report" (pun intended) meant that the solvent had "totally" evaporated; that is, the piece was no longer "wetted" by, or wet with solvent. Far as explosive energy available per unit surface area, it's low, but still energetic enough to be a problem (initiation of other reactive hazards, cardiac arrest, such like).

 

[wxrocks]

I don't know what is being more corrosive with absolute certainty, but judging by the limited view inside the current tank it is the liquid that is causing the biggest problem. However, I don't think vapor is an issue because the tank regularly sees gauge pressures of 3-5 PSI. With the low vapor pressure and the fact of the vapor being 11.9x air density, I would venture the vapor isn't "wildly" contacting the metal in the airspace.