Here is a WAG on tha:
Ozone is O3, a molecule with three atoms of oxygen and is much more
chemically active than O2 (what we breathe ordinarily.) O3 is much more
corrosive than O2. When O3 comes into contact with H2O (water) it
dissociates into an O2 and a plain O. When Ozone is coming apart into a
bunch of O2 molecules and elemental O, the the plain O atoms will
combine to make O2. The end result is that in the p[presence of
moisture in the air the ozone ends up as ordinary oxygen molecules (O2)
which is not as corrosive as ozone (O3)
Now then, just maybe there is more moisture in the air closer to the
ground due to evapotranspiration (The process by which water is
transferred from the land to the atmosphere by evaporation from the soil
and other surfaces and by transpiration from plants.) More moisture in
the atmosphere near the ground = less ozone near the ground = less
corrosion near the ground.
Just a WAG or perhaps a SWAG (scientific WAG.)
Or maybe it is Menehunes (the Leprechaun like little people of Hawaii)
playing with us.
Patrick NJ5G
On 3/8/2014 5:26 PM, Steve Maki wrote:
On taller towers (500' or more) we often see rustier hardware near the
top then near the bottom. I always assumed that the air was more
corrosive up there on average. Well I guess that must be a given :-)
Not sure why that would be though.
-Steve K8LX
On 3/8/2014 4:04 PM, Donald Chester wrote:
In recent years, the guy wires on my tower have become what may be
dangerously rusty, and I plan to re-guy. The tower is 127' tall with
four guy levels, one every 30 feet.
The rust pattern is very interesting. The guys at the top two levels
are far more rusty than at the bottom two, even though all the guy
cable came from the same roll. I could probably get by with the
original bottom sets of guys for many more years, but the top two
definitely need replacing, sooner not later.
The only reason I can possibly figure for the differences in the rust
pattern is that the slope of the upper guys is much steeper, and
water would tend to run down the the wire and stay in contact with
the metal for longer, whereas the lower guys are closer to
horizontal, enough that water would tend to drip off instead of
running down the wire all the way to the end. The amount of rust is
nearly the same on the top set and next one down, and nearly the same
for the bottom set and next one up, but the difference between the
second and third guy level is tremendous.
Don k4kyv
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