K4SAV wrote:
>I'm assuming your tower is really galvanized steel and not raw iron.
>
>
>
No it is not...
It is really raw iron as I wrote the same use for rebar (the iron which
goes in the concrete, is this the wrong term rebar?)
>I posted this message about a year ago. It seems to go against
>conventional wisdom around here, but I got no response from anyone.
>Maybe the info is correct (seems correct to me), or maybe no one wanted
>to make the effort to reply. Anyway here it is again.
>
>The way most people do it is to put a stainless steel shim between the
>zinc tower and the copper wire and clamp it. Polyphaser makes clamps
>that work like that.
>
>That said, doing it this way doesn't make any sense to me. You have at
>least three goals in avoiding galvanic corrosion.
>1) Maximize the contact area of the least noble metal exposed to the
>electrolyte (water),
>2) Minimize the potential difference between the metals in contact, and
>3) Keep the water out.
>
>1) The least noble metal in this case is the zinc tower, but the contact
>area is the same for both metals because water may collect within the
>junction but the whole tower is not going to immersed in a liquid. So
>item 1 (in the case of what is in contact with the tower) is a moot point.
>
>2) The least noble metal will corrode. The higher the potential
>difference, the faster it will corrode. If you look at the small list
>below, you will see this is the zinc (your tower). In order to avoid
>this you should put something as closely matched to the tower as
>possible, and let whatever comes next do the corroding (you can easily
>replace that, if need be).
>
>In the galvanic series, in flowing sea water, in order from least noble
>to more noble:
>zinc is -.98 to -1.03
>aluminum alloys are -.76 to -1.0
>copper is -.3 to -.37
>tin is -.3 to -.33 and
>stainless steel varies a lot depending upon the alloy and may be -.57 to
>0.0.
>
>
Where did you get this values?
An of course in my case if I have a raw iron tower - is there any
material which corrodes instead of the iron?
As I understand all materials here are more noble and therefore my tower
will corrode :-(
I already was thinking if I put apart an lightning conductor instead to
use the tower itself.
Do you have a seperate lightning conductor for you tower?
I tought to put the lightning conductor isolated from the tower down and
use this also as ground for the equipment...
Is this a good or bad idea?
>Looking at this table, I can't figure out why people use stainless steel
>next the their towers. I would think an aluminum alloy would be a better
>choice. After going through this exercise, I decided to use one of the
>standard AC entrance panel aluminum alloy ground lugs (Home depot,
>Lowes, or any electrical house), since my tower requires a clamp that
>can be mated to a flat surface. I think some of these may be tin plated,
>others are not. Don't use the tin plated ones. I used an oversized
>
>
That's the problem. What I can get here where I live (Argentina) the
most is tin plated clamps ...
But I will have a look aroung maybe some special vender has other stuff ...
>clamp because I liked the robust clamping screw it had. I bent the end
>of my #4 ground wire into a tight J loop, which I placed under the screw
>
>
Do you mean the ground wire which is in the earth or the ground wire
which comes from the tower?
And I don't right understand you did put aluminum entrance panel but
you used copper wires for the grounding
system, right? Is this because of there are only ground roads of copper
and you want the corroding site not below
the earth? Because if not so why not use aluminum wire for the grounding
system?
>to gain more surface contact area. When you tighten the clamping screw,
>the copper wire actually squashes into the aluminum a little. These
>clamps work well under a tower bolt after you file off the little ridge
>on the bottom of the clamp, and you will probably have to drill the
>mounting hole larger.
>
>I coated the aluminum alloy to copper junction with an anti-oxidant and
>sealed it against water. I used duct seal to encapsulate the whole thing.
>
>
>
Yes that's the way I want to do. I wantg paint it with a very good
(expensive) anti-oxidant which is used for cars
and over that a very good painture
Thanks a lot for your help!! I really don't know which way to go that my
tower will work many years right.
And here nobody has much idea about that!!!
Beat
>Jerry, K4SAV
>
>Beat Meier wrote:
>
>
>
>>Hello
>>
>>I want connect my tower parts (6m each part) with a copper wire 35mm²
>>each leg (3 legs).
>>How can I do that?
>>I get copper tinned stuff with bolts which can press the copper wire on
>>one end and
>>at the other end I can put it to the iron tower and paint the whole stuff.
>>But my question is: Does the iron react with the tinned copper?
>>And more over: If I would use cadwelding which creates copper arround
>>the connections
>>this really would react havely with iron ...
>>
>>So what does you guys do to connect "something" to iron towers?
>>BTW: The iron is the same as used for rebar ...
>>Would it better to use some stuff of aluminium or stainless?
>>
>>Other question for the chemicals: What is the clue with the chemical
>>table of the elements i.e. which metals don't react with
>>others like Gold (Au), Silver(ag), Copper (Cu)
>>This are all in the same column (11) but iron is in column 8 and Tin in
>>column (14) so what chemical values are importend to see if there
>>is a redox reaction?
>>
>>Thanks for any infos
>>
>>Beat
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>>
>>
>>
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