Solar Metals

So, my kW of solar panels came in. The frames and z-brackets are aluminum and the hardware (5/16x2-1/2" lags and 1/4-20 bolts) is 304
stainless. I picked up Unistrut to hold it and it has galvanized nuts. Will there be hell to pay from electrolysis, and, if so, is there any way to mitigate it? Rubber discs under the washers?
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I used those combinations plus brass on the antenna and solar panels for many years without a problem. Maybe the LPS-3 I spray on them helps?
LPS-3 doesn't protect aluminum from chlorinated town water. So far Ox-Gard has kept the aluminum garden hose fitting screwed onto a brass vacuum breaker clean. It works well on aluminum antenna elements with copper fork terminals and stainless screws in place of the original rivets. http://www.gardnerbender.com/en/ox-100b
Every few years the signal quality decreases and when I take the antenna down the element-to-element resistance measures around an Ohm. I scrub the joints, apply Ox-Gard and then measure maybe 20 milliOhms between them, as the voltage drop with 1 Amp passing through.
--jsw
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On Sat, 9 Jul 2016 09:21:40 -0400, "Jim Wilkins"

That's excellent news. Thanks, Jim.
WTF? $22 a can at Amazon? YGBSM! ($15 eBay, better)

I'm on a well, so that's not an issue here, but I tend to lube my hose ends every year or two with whatever grease is handy. Moly and white lithium in a can are two, but I now have a tube of synthetic which is nice, as well. I -hate- stuck hose fittings. Lube goes on nylon, brass, and aluminum ends, regardless.

Oh, joys. I remember antenna maintenance/replacement eons ago. It was never much fun.
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wrote:

The antennas telescope down to roof level and are quick and easy to remove. Raising them is harder because the guy lines tangle, but I don't have to do that quickly as a storm builds.
The pulley system that raises one is a home made aluminum, stainless, brass and galvanized assembly that's been exposed to the weather for many years. When I inspected it and hit the fittings with marine trailer hub grease last weekend it was in fine shape.
I think I've temporarily assembled the antenna elements with stainless screws when I ran out of aluminum ones without any corrosion problems, which would appear quickly as poor reception. The waxed wood insulators needed longer screws than the molded plastic ones.
Hearing about $160 cable bills reminds me that my antenna system isn't -that- much of a nuisance to maintain. --jsw
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On Sun, 10 Jul 2016 07:11:38 -0400, "Jim Wilkins"

How many storms/yr force you to do that?
Do you loosen your guys prior to dropping? I've only known one person who blunt-forced his antenna back up with the guys untouched, and he probably shortened the life of his ridge roofing by 15 years.
I found that loosening them (just two anchor points on the top two sections of a 3-section pole) by about 6" each made it a whole lot easier to telescope the pole back up. They always need a scosh of retightening anyway.

Excellent.

I remember talking with you about that a few years back. How are they holding up?

Yeah, really. <g>
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wrote:

Perhaps once in 1 or 2 months. Everyone else's used weather funnels out through New England. We see all types from Arctic blizzards through tornadoes and Gulf hurricanes (Katrina), but rarely at full intensity.

There are two sets of guy lines. The lower ones run over pulleys at the mast attachment and tie off at the base, so I can look up and adjust them to straighten the mast since that's nearly impossible to do from the outer ends. The upper ones are tied at the top with enough slack that the antenna can sway perhaps half a foot, which I learned to do at Mitre. Then I loosen the lower ones to reduce the column loading on the mast.
The lower ones are weighted to take up the slack as I lower the mast, so they don't drag and snag on shingles. The upper ones just blow around and catch on the chimney etc. When I raise it I may have to unsnag them with a telescoping pool cleaning pole.
A very handy jam cleat on the mast base holds the raising rope while I untangle a guy line. http://forum.woodenboat.com/showthread.php?151343-Wooden-Jam-Cleat
If I don't have to replace a bent mast section the guy lines hold their adjustment pretty well through lowering and raising. The antenna jerks sideways to warn me if one pulls tight early.
Radio Shack masts folded. Chain link fence rail masts bend gradually and can sometimes be straightened in a forked tree.

The signal level has dropped so I'll find out soon.
--jsw
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On Sun, 10 Jul 2016 11:14:09 -0400, "Jim Wilkins"

Egad, that's a lot. Condolences.

Interesting. I've never left slack, but I've never lived in a high-wind area, either. I've only lost one mast, and that was due to not having replaced the 20 y/o rusted guy wires.

Yeah, those long uppers have too much play and move all over the place with the slightest wind. I always try to do my antenna work in the early morning, when it's very still. It's a helluva lot safer and most indubitably easier.

Cool.

Ah...
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wrote:

I lower the rotator down the track on the lower end of the mast support post if winds over about 40 MPH are predicted, usually when a Canadian cold front passes through as a line squall. Some of the guy lines are anchored to trees that could drop branches on them. Lowering the antenna the rest of the way to the roof requires removing mast tube sections from the bottom (rotator) end but running up or down the track isn't much bother.
--jsw
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On Saturday, July 9, 2016 at 8:35:16 AM UTC-4, Larry Jaques wrote:

No, just lightly coat all surfaces with Johnson's wax.
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Use original Duralac anticorrosive jointing compound on all fasteners. <http://www.llewellyn-ryland.co.uk/duralac.html If you have a large area of other metal in contact with aluminium, use a vinyl or mylar tape gasket stuck to the cleaned aluminium surface and trimmed to be only fractionally larger than the contact area. If you use a loose gasket, you *MUST* use Duralac or similar on the face touching the aluminium to prevent poltice corrosion.
That should give you acceptable corrosion resistance even in a coastal area, or with high air polllution or within the spray drift zone of a major highway thats salted in the winter.
--
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[dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL
Barium Chromate, its active ingredient, is known to the State of New Jersey to be toxic and potentially carcinogenic, and they are our experts on hazardous waste spills. . http://nj.gov/health/eoh/rtkweb/documents/fs/3074.pdf
--jsw
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<snip>

Yep. Chromates are generally highly toxic. However most Barium salts are virtually insoluable, and Duralac has an organic binder which minimises leeching out of the joint. It has a long track record as a reliable anti-corrosion jointing compound in the aviation and marine industries, and as long as its stored safely, applied in accordance with its safety instructions and any excess is carefully cleaned up and the waste disposed of in accordance with local HAZMAT regulations, is minamally hazardous.
There is also the reformulated Chromate free Duralac Green, but it doesn't have anywhere near as long a track record. However if local regulations prohibit Chromates, its probably your best option.
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The chemists' memory aid for Barium (Bury-'em) salts is:
"Sulfate he ate, sulfide he died."
My experience ordering books from England has kept me from ordering anything else.
--jsw
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On Sat, 9 Jul 2016 15:12:10 -0000 (UTC), Ian Malcolm

I think I'll baste the parts in something like that during assembly.

Thanks, Ian. No salt, no coast, so I'm in good shape.
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Larry Jaques wrote:

Don't use "rubber" next to aluminum. We had a Dodge van that had rear A/C. The refrigerant lines were aluminum, and they were supported every foot or so by clamps that had a rubber insert. The lines were in great shape, EXCEPT where clamped. At these locations, they had turned into sponge. Maybe road salt got in there and remained, but my theory is that the rubber exuded some sulfuric stuff that ate the aluminum.
Jon
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wrote:

Funny you should say that. The corners of the frames were padded with high-quality Chiwanese rubber strips and angle aluminum during packaging for shipment to me. <g>
I had considered using those under the z plates above the Unistrut until you mentioned it.
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Larry Jaques wrote:

Any sign of corrosion or discoloring of the aluminum?

Well, of course, there are TONS of different "rubber" materials. I would definitely avoid real vulcanized rubber. You can probably detect that stuff immediately from the smell. There are all sorts of plastic, silicone, etc. types of materials that might be fine. (Many silicone caulks release ammonia as they cure, causes the same problem.)
Jon
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wrote:

You want smell? Haven't you ever smelled Chiwanese rubber? One whiff leaves a nasty odor in your nostrils for days. I leave it outside for 2 weeks before bringing it indoors. Nasty, nasty, nasty.
I think a $15 can of LPS-3 will baste the parts well enough to prevent much, if any, corrosion. One baggie, 24 z-plates, 24 fender washers (strength), 48 stainless bolts, 24 stainless nuts, 24 Unistrut nuts, 16 lags, and 16 washers. Spray and swish. As the lags go in, they'll be douched with silicone caulk. I'll put 2x3" flashing above the two rows of Uni for good measure, too.
I might have time next week. Gotta find a helper first, though.
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On Sat, 09 Jul 2016 05:35:37 -0700, Larry Jaques wrote:

JBWeld? Not to make it so you can take things apart later -- just to remind you of the futility of it all.
--
Tim Wescott
Control systems, embedded software and circuit design
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wrote:

Galvanized fasteners are quite resistant to galvanic corrosion with aluminum. And the steel underneath the zinc is also fairly benign with aluminum. In fact, the aluminum will act like a sacrificial anode against plain steel, but the activity will be very low. The zinc barrier should hold up for a long time.
Stainless, as everyone knows, is deadly against aluminum. You might get enough juice out of that galvanic cell that you should wire it in with your solar cells, to make a hybrid battery. d8-)
--
Ed Huntress

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