OT- What is in PVC smoke/soot that gives bare cast iron and steel color?

[Gordon Heaton]

Had a small fire in the shop New Year's eve. The fire was contained entirely in the top of a good-sized toolbox but the smoke and soot blanketed everything, upstairs and down. After cleaning the machines, the bare steel and cast handwheels, etc. have a soft golden look as though they'd been coated with a UV resistant clear urethane. Or, if you're familiar, they look like bare cast aluminum treated with Alodyne.

What caused this? Wiping with toluol and acetone has no effect. I don't care if it never gets removed, my machines are for work, not show, but I'm curious.
END of short story.

LONG story: I'd plugged a phone and a drone in to charge. Neither had been used for at least 3 years. They were supplied by the USB charge ports built into the tool box. One of them caught fire. In this area were a lot of PVC-cased tools and equipment such as an oscilloscope, Fluke87, cordless tools, cameras and so forth. The high-capacity DeWalt tool batteries went off too, helping to keep the fire going. I found out about it the next day after all was cold and settled out. The tool box lid was almost closed at first, with a 1" gap along the bottom edge because the DeWalt tools were too tall standing up. As the tools slumped during melt the lid closed completely. So far, $2800 in equipment and roughly $15,000 in clean-up. My insurance company has been absolutely stellar, thank heaven.

 

[Limy Sami]

Chlorine? .....''smoke'' Rigid threading oil on a lathe and the chucks change colour.

 

[Gordon Heaton]

Hadn't thought of that. I bet you're right. It was impossible to breathe in there until I had the big blower going for a while.

 

[Milland]

When I was a little Milland (many decades ago), I was in tech HS and still with my folks. A fire started in their new kitchen (ciggy butt that hadn't been fully extinguished), and while it wasn't a terrible fire it did set much of the PVC flooring up, and yes, the smoke and fumes went EVERYWHERE.

I had a number of steel shop projects sitting around the living room (hey, they looked nice), and either from the smoke or some residual water spray from the fire department were all rusty when I recovered them. I think it was mostly the smoke, I don't remember there being a lot of actual water damage.

Polyvinyl Chloride - I think the culprit is in the last word.

 

[Rollerman]

Burning PVC generates Hydrochloric Acid fumes.
Nasty, irritating and toxic.
Molding PVC can be interesting, PVC can start to decompose in the barrel of the molding machine if it get too hot or is held in the barrel too long.
PVC can also eat injection molds

 

[rklopp]

Another interesting thing I discovered is that hot PVC next to acetal (Delrin) makes the acetal look like termites ate it. I had a motor encased in a PVC sleeve inside an acetal submersible pump housing overheat, and the inside of the housing was full of what looked like termite tunnels.

 

[M.B. Naegle]

Our work stations on the mechanic/assembly side of the shop have their own individual service disconnect switches with stack lamps for both high and low (110v) volt power in those areas and I'm a stickler about shutting it all down at night. I've gotten some flack about needing batteries to charge over night and similar "can't I just plug it in to the wall over there?" scenarios, but my gut always says 'no'. Too many old tools, machines being worked on with unproven components, etc.

At our old shop, the vertical band saw (old 1950's DoAll), just started billowing out green noxious smoke one day out of the blue. Luckily we were there but we found that the service disconnect was always left on keeping the old transformer constantly energized, and that day it finally got too hot. After fixing it, I broke off the work lamp switch so it was always on (as an indicator), and we got our act together about turning machines and work stations off at the end of the day.

Glad your experience wasn't worse, but thanks for sharing.

 

[gustafson]

REminds self to not charge things in the top of Gerstner.....

THat is really lucky that it did not go sideways

 

[mhajicek]

Yep, that amber color is the beginnings of rust. Nip it in the bud.

 

[gbent]

Yes, and lost in the news about the tragic New York City apartment fire was another fire in New York City. The lost fire started in a restaurant where employees were charging electric bikes. One of the Lion batteries exploded.

Expect to see more similar fires, especially as we all buy aftermarket batteries to support old but useful cordless tools where there is either no longer battery support, or the battery support is priced so high to induce you to throw the tool away.

As for the result of to many devices charging at one time, search for stories on the dive boat that burned off the California coast. 34 died there.

Probably a business opportunity for someone to build steel charging stations with a self closing door held open by a low temperature melting link, just like some parts washers.

 

[Gordon Heaton]

. . .Glad your experience wasn't worse, but thanks for sharing.

Thanks! Yeah, I'd heard stories but never thought too much about putting stuff on the charger and taking off. The items in question were low-budget things, likely with deficient or non-existent battery protection. I'd been storing them in the upstairs room at the shop, and had I plugged them in there the shop would have been a total loss. I consider myself blessed, and educated!

 

[rustyironism]

I can't help with the PVC question but I learned...twice.. that Dewalt battery chargers will catch on fire.
Luckily both times I was in the shop, but I never leave them plugged in if I am not very nearby.

Mike

 

[Chip Chester]

Good to know. I don't think I've ever unplugged them.

 

[plastikdreams]

The major gaseous products of the combustion of PVC are hydrogen chloride, carbon monoxide, water, and carbon dioxide. Chlorine is not produced, also a lot of plastics can give off phosgene, hydrogen cyanide,and other toxic compounds as products of combustion but pvc gives off little to no phosgene.

 

[rcoope]

Another interesting thing I discovered is that hot PVC next to acetal (Delrin) makes the acetal look like termites ate it. I had a motor encased in a PVC sleeve inside an acetal submersible pump housing overheat, and the inside of the housing was full of what looked like termite tunnels.

That's really interesting. I work in lab automation where we often use or are tempted to use Delrin, but it according to data sheets it does not tolerate unusual chemical conditions at all well, in particular high pH found in decontamination reagents like bleach and sodium hydroxide. So we use HDPE instead, which is fine but not quite as nice to machine of course. I've never tried dropping a piece of Delrin in bleach though, so I don't know how fast it actually degrades. I should do that experiment given there's a lot of bleach around what with all this Covid PCR testing....

 

[CalG]

Damn Li Ion Batteries!

Thanks for the prompt, I've got a couple on the charger downstairs. I'm pulling them off NOW!

 

[Peter from Holland]

PVC can also eat injection molds

That is why these are made from 16% Crome steel
And even then

Peter