Sulphamic acid and aluminium

[Simon]

I need to clean out some partially blocked coolant passages inside an
aluminium radiator. The radiator is out of a railway locomotive and
is not easily dismantled (it is all welded construction).

I am told that sulphamic acid will remove the deposits - my concern is
that it will do a fairly good job at removing the aluminium too.

Apart from the obvious answer (i.e. start at 5% solution and work up
gradually) does anyone have a suggestion as to what solution is the
best compromise between removing oxidisation and time taken?

Thanks in advance.

Simon

[faro...@hotmail.com]

If your recall, concentrated nitric acid is unable to react with
aluminium due to the formation of oxide layer. Sulfuric acid attacks Al
rather very slowly. I don't think such a weak acid would be able to
damage the metal considerably assuming the deposits of calcium
carbonate would be preferrably dissolved.

[Uncle Al]

Do you know what is causing the clog? Alkaline earth carbonates and
whatnot are effectively attacked and solubilized by sulfamic acid.
Warm an aluminum test coupon in the solution for a day or three to
confirm it doesn't go after the metal. Stuff like Lime-Away and CLR
(phosphoric acid plus organic chelating agents) are more aggressive
and faster, but may eat metal. Test before you try.

Rinse the Hell out of the cleaned system before you refill and run.
Aluminm is eaten by both acid and base.

Ideally your coolant would be distilled or deionized water (no
halide! no hardness, no solids) plus an anticorrosion package (perhaps
dichromate. Enviro-whiners will have a fit). Automative organic acid
technology (OAT - "never change your coolant again") lives up to its
billing under perfect circumstnaces. The world is a dirty place. Use
ordinary Prestone diluted 50:50 with distilled water, add more mix as
necessary over time, and change every two years.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf

[muha]

try 5% vinegar first, overnight. Then flush with water and see.

[HNO3]

Don't use vinegar, it eats aluminum. concentrated nitric eats Al, but
dilute doesn't.

[Uncle Al]

HNO3 wrote:
>
> Don't use vinegar, it eats aluminum. concentrated nitric eats Al, but
> dilute doesn't.

Those who know nothing should reply in kind.

[Douglas Scot Gillman]

Internet cloaca strong timing.

Dream on nacelles' wind, Caught in tepid Tome, an urge,
Gin in from the cold.

[HNO3]

Unfortunately, what I said is personal experience.

[Oscar Lanzi III]

How strange! It has long been known that Al is resistant to
concentrated ntric acid, at least when cold. So is iron. At work one
of my co-workers showed me a paper where they were analyzing galvanized
coatings for aluminum. They dissolved off the zinc (not pure zinc;
there's a little aluminum in the zinc spelter used to apply the coating)
with fuming nitric acid, and when it gone the Fe-Al compound at the
interface between zinc and steel passivated. Then the passive film was
broken down in dilute sulfuric acid. That gave two different solutions
that could be analyzed to determine aluminum distribution between
coating layer and interface.

--OL

[HNO3]

Maybe I had Impurities in my nitric...*sniff*... The quest for pure
nitric goes on...

[dccin...@gmail.com]

[dccin...@gmail.com]

On Friday, 4 February 2005 19:23:34 UTC+5:30, Simon wrote:

i am using sulhamic acid for radiator cleaning which are made of alumunium. is it safe to use 5% solution to descale or we should use inhibitor foralumunium..i am using sod carbonate to stabilise the system.kindly adic. mail dccin...@gmail.com

[Peter Jason]

Not really. Here we use 2% oxalic acid, but a large throughput
(turbulence) will have a better chance of cleaning.

To be sure test some of the corrosion etc by soaking in the cleaning
solution.

Hydrofluoric acid (as 2% soln) rapidly cleans aluminum but its action
must be watched and controlled.

Also, try YouTube.