1. Home
  2. ⏣ General Metalworking
  3. What's the acrid dust when wire-brushing battery terminals?

What's the acrid dust when wire-brushing battery terminals?

I guess this is stretching the concept of metalworking, but rcm seems like the best place to ask...

Last night I used an air gun to clean out the burner of the antique side-arm gas water heater attached to my antique outdoor hot tub. Expecting the usual small puff of greasy black fine soot, I just turned my head away and squeezed the trigger - and was totally engulfed by a cloud of acrid, white fine powder. In between fits of coughing and choking, I kept thinking, "this stuff is familiar."

Over an hour later, still coughing and tasting the stuff, I made the connection. It was the same stuff you wire brush off of corroded but dry lead-acid battery terminals.

The heater is two spirals of some kind of copper alloy tubing, in a cast iron housing over a cast-iron burner. The only other possible ingredients would be minerals from my water (but I don't see any evidence of major leaks), or something that arrived with the propane. Nothing like this had ever formed in the heater in the previous twenty years.

Thinking about it, I'm not sure what the ingredients are in the battery situation. I've seen it on lead post car batteries and on presumably solder-tinned gel-cell terminals. The mating parts have variously contained lead, steel, copper, tin, cadmium, zinc, and probably other metals, with the only constant being the lead and sulfuric acid inside the batteries. But the dust always smells/tastes the same...

As far as I can imagine, there is no lead and no acid involved in my hot tub. What can this acrid powder be?

Loren

Reply to
Loren Amelang
Loading thread data ...

Sulfur is a common trace contaminant in petroleum fuels and gasses. That would explain sulphates on the coils. Have you changed suppliers recently? MadDog

Reply to
MadDogR75

On battery posts, it'll be some combination of lead sulphate and probably lead carbonate. On your coil, I have no idea, mercaptans are used for odorizing both propane and natural gas, they have sulphur in them. Some brass has lead in it, might be there was a reaction there. Would have to be a LOT of gas burned for that to happen, the odorizer is present in very small proportions. Might be the propane had a high suphur content, it happens. If the heater was old enough to be around when there was town gas, that had sulphur in it from the coal used to form the gas. There'd be some tar, too. Used to be a blind downleg on most gas lines at the entry to the building for a tar trap, in my hometown, a lot of old houses still had them. Full of tar, naturally.

Stan

Reply to
stans4

The white powder on the battery terminals is zinc sulfate, produced by the action of sulfuric acid on the brass cable connector which is an alloy of copper and zinc. Most likely your water heater coil is brass or uses brass fittings and has corrroded somewhat, leaving a zinc compound. Engineman

The whie powder on your

Would have to be a LOT of gas burned for that to happen, the odorizer

Reply to
engineman1

...

The outsides of the coils are not visibly brass at all, they have various colored hard coatings. I try to keep the thicker stuff brushed off, but don't ever clean them down to bright brass. Hard to imagine much chemical reaction there. But I guess it doesn't take much lead out of a battery terminal to make a mountain of white corrosion...

Actually, the heat has been mostly solar lately, comparatively little gas has been needed.

I'm going to go with that theory. I haven't changed suppliers, but my supplier closed their nearby location and is hauling gas from another site. The gas definitely changes - some tanks are full of pink goo, some make way more of the greasy black soot. I guess the last one had excess sulfur.

Never seen one with tar in it. But I grew up with natural gas. I've seen modern equipment specify a downleg, as a dirt trap.

Loren

Reply to
Loren Amelang

Aha... A zinc component seems to fit better with the smell/taste of the stuff than lead does. It has a little of the taste of an old selenium rectifier, but I've never known if that was actually the selenium or some processing artifact.

Thanks!

Loren

Reply to
Loren Amelang

Was your rectfier soldered to the wires? Soldering paste usually contains zinc chloride which has a very astringent taste like all soluble zinc compounds. Selenium tastes more like garlic. Engineman

Reply to
engineman1

Guys

Describing soldering and electronics chemicals by smell is one thing, but taste?

I've spent a lot of time on an electronics bench and i cant ever say i tasted my circuits

Brent Ottawa Canada

Reply to
Brent

On Sun, 10 Jun 2007 07:12:06 -0700, with neither quill nor qualm, Brent quickly quoth:

"Here, Fred. Taste this." Oops, sorry; it -was- arsenic after all."

Intimacy problems abound, Brent.

================================ I drank WHAT? --Socrates

Reply to
Larry Jaques

Selenium gas is hard on the lungs and is poison.

I evacuated the house as a teen when I mounted a Selenium rectifier stud (plates with bolt through) to the chassis of my home made A.M. radio. Tube type naturally.

It was during a football game when I tried it out...

Martin

Mart> >>

Reply to
Martin H. Eastburn

You silly boy! That's what LONG extension cords are for! Set it outside before you plug it in.

Reply to
Michael A. Terrell

Back then there were not any long extension cords unless you made it yourself. Mowers were 2 stage oil burners.

Martin

Mart> "Mart>> Selenium gas is hard on the lungs and is poison.

Reply to
Martin H. Eastburn

I've got plenty of 50' ant 100' cords. When I was a kid it was easy enough to find a ready made 12' cord, or a pile of 6' cords at about any retailer ot department store. That was in the '60s.

Reply to
Michael A. Terrell

The late 40's and 50's were a bit more living without times. Mostly do it the old way or not at all. Lots of hand-and-knees work.

Martin

Mart> "Mart>> Back then there were not any long extension cords unless

Reply to
Martin H. Eastburn

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.