Preparing for a XC : Bathroom Breaks

Sigh.

It is not its pH that makes urine corrosive, but the dissolved salts
that become reactive. That's why cars that are close to the oceans rust
more quickly than do those in rainy inland locations.

Sooner or later you may get something right. Let me rephrase that.
Sooner or later you may apply a known fact correctly to the situation
being discussed. That urine is more or less neutral, or even more
importantly has little buffering capacity, is true, but that fact is
not relevant to the topic.




On Jan 26, 8:14 am, Mxsmanic wrote:
Thomas Borchert writes:
You mean, regularly spraying a highly corrosive fluid onto the
underside of your plane, which then creeps in through every opening and
seam, sounds good? I don't get it...Urine is not highly corrosive. It's mostly sterile, dilute salt water
with a bit of urea, and a neutral pH.

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Tony writes:

It is not its pH that makes urine corrosive, but the dissolved salts
that become reactive. That's why cars that are close to the oceans rust
more quickly than do those in rainy inland locations.

Urine isn't usually terribly concentrated. Some of the byproducts of
urine that are produced after exogenous microorganisms attack it (such
as ammonia) are much more damaging.

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The bridge mentioned earlier will take comfort in that.

On Jan 26, 12:51 pm, Mxsmanic wrote:
Tony writes:
It is not its pH that makes urine corrosive, but the dissolved salts
that become reactive. That's why cars that are close to the oceans rust
more quickly than do those in rainy inland locations.Urine isn't usually terribly concentrated. Some of the byproducts of
urine that are produced after exogenous microorganisms attack it (such
as ammonia) are much more damaging.

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Tony writes:

The bridge mentioned earlier will take comfort in that.

People have been urinating on bridges for thousands of years, and I
don't know of any that have collapsed as a result.

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I just remembered something. I think it was with you that during a
discussion regarding the physics of a 1 G roll pointed you to a rather
nice web page where someone using classical newtonian physics showed a
family of loci that me that criterion, and you were unable to follow
the analysis and so declared it invalid.

That was simple physics, force equal mass times acceleration kinds of
stuff. Here we're talking about the reaction dynamics in inorganic
chemistry, and earlier, human physiology. Seems to me if you don't have
the tools for the simple stuff -- that roll stuff is calculus that can
be done long hand -- you don't have the tools for this either.

You are good at taking singular facts and misapplying them. Is there a
market for that skill in France? Here in the US we tend to elect such
people to public office. Or, if they work for us, we fire them.

I should badly doing this -- if MX was a cat I'd be cited for being
cruel to animals -- but I don't.


On Jan 26, 3:27 pm, Mxsmanic wrote:
Tony writes:
The bridge mentioned earlier will take comfort in that.People have been urinating on bridges for thousands of years, and I
don't know of any that have collapsed as a result.

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On Jan 26, 12:49 pm, "Tony" wrote:
Sigh.

It is not its pH that makes urine corrosive, but the dissolved salts
that become reactive. That's why cars that are close to the oceans rust
more quickly than do those in rainy inland locations.


Tony,
Here is another example of the corrosive effect of urine
http://tinyurl.com/26ghv8

"On the pitting corrosion of high strength aluminium alloys by rat
urine
Sreekumar, K; Jacob, E; Natarajan, A; Lakshmanan, T S
Praktische Metallographie (Germany). Vol. 34, no. 9, pp. 478-481. Sept.
1997

High strength AFNOR 7020 aluminium alloy sheets in T6 condition are
used for fabricating propellant tanks (nitrogen tetroxide N sub 2 O sub
4 and unsymmetrical dimethyl hydrazine UDMH) for launch vehicle
applications. These tanks are fabricated through welding route and are
filled with dry nitrogen gas at 300 mbar and sealed at both ends. The
tank is then cocooned with aluminised plastic sheets and stored under
positive dry nitrogen gas pressure. During the storage rats had cut
open the aluminised plastic sheets and had urinated all over the
surfaces of the aluminium alloy tank. The tank surface showed
discolouration and severe pitting corrosion attack wherever the rat
urine had come in contact with it. This paper highlights the
investigations made to understand the severity of the corrosion attack
on the surface of the tank with a view to clear it for further
processing and utilisation.

I'd bet someone will argue that rat urine is not the same as
human stuff. The counter argument is that some people are considered
'dirty rats' ;-)

By the way, the pH level of human urine can range from 4.5 to 8
and normal urine is slightly acidic.