
Lab explosions and accidents - epsylon
http://uvicrec.blogspot.com/2015/12/lab-explosions-and-accidents.html
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brandmeyer
Once upon a time, in the nuclear submarine navy, my shipmate tags out the
ship's battery breaker. As part of the tagout, he checks that the ship's DC
bus is deenergized - within the battery breaker box itself. During the check,
he finds some voltage, which isn't entirely unexpected, since there is enough
capacitance on the DC bus to hold it charged for a while. So he uses a
specialized grounding probe - about 1/8" diameter copper rod with a reinforced
handle - to discharge it. Unfortunately, he has misunderstood what was inside
the breaker box and is actually shorting out the ship's main battery! This is
a couple hundred volts DC, and a few thousand amp-hours of capacity, and it
delivers enough current to instantly vaporized the grounding rod. He's knocked
on his ass by the arc blast. Fortunately, he was correctly considering the box
to be energized gear and was wearing a full set of PPE, suffering only minor
flash damage to his eyes.

~~~
jacquesm
Lucky guy, lucky too he used a relatively thin rod, a thicker one and it would
have been quite a different ending.

I did a similarly stupid thing one day. While repairing a clock for a display
on a trade show I hooked the ground crocodile clamp of my scope to what I
thought was the ground but which in fact was V- of the DC supply voltage of
the neon light installation that was use to drive the display. I had a blind
spot in the middle of my eyes for many days after that (and took out a fairly
large chunk of the mains supply for the Eastern district of Amsterdam). The
crocodile clamp totally disappeared, the scope, miraculously survived and
wasn't even out of spec.

Every time I use a crocodile clamp to hook it on to something I think back to
that moment when the clamp makes contact and some part of me expects it to
happen again.

~~~
brandmeyer
> I hooked the ground crocodile clamp of my scope to what I thought was the
> ground but which in fact was V- of the DC supply voltage of the neon light
> installation that was use to drive the display.

Yeao! I own a couple of high-voltage differential probes for this very
purpose. Even though most single-ended scope probes are rated to 300V Cat II,
I won't go anywhere near main's power with them.

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geerlingguy
Early on in my 'take things apart for fun' youth, I knew that capacitors held
a charge long after power was removed. So when disassembling a camera with
built in flash, I popped off the small board holding the 330V capacitor and
thought it would be a great idea to discharge it using the end of my needle
nose pliers—for the tiny capacitors I'd done this to before, it might've
caused a tiny spark, but nothing more.

Well, I learned a valuable lesson that day; even relatively harmless camera
flash capacitors can pack quite a charge days after a battery's been removed!

The giant spark made me jump back and fall over my chair, and my pliers still
have two nice molten burn marks where it touched the contacts. I'm just glad
the pliers had rubber handles!

I'm much more cautious around capacitors these days.

~~~
peter_l_downs
Not to brag, but my friend Sean and I are much dumber than you. We took the
capacitors out of two disposable cameras and hooked them up inside the casing
of a 9v battery – our "9V Taser", we called it. Looked great, but then of
course we needed to test it. We decided to do the honorable thing and self-
experiment; being the younger and slightly more foolish, I was the subject. We
charged it up and he touched it to my arm. I remember my heart sort of
"skipped" and I felt really weird for the next couple of hours. Ah, youth.

~~~
mbrameld
Similar, but stupider, in my mid 20s while in the Air Force my buddy and I
built a rail gun out of disposable camera capacitors. It didn't take long
after getting the first capacitor out for us to wonder and discover what it
would feel like to short the leads on our skin. That soon turned into a game
of tossing a loaded capacitor to the other at various times throughout the day
in the hopes that the natural reaction of catching something tossed your way
would kick in before the brain figured out what it was catching. Your tax
dollars at work.

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David
In chemistry class in middle and high school, I thought all the safety
precautions we took were stupid, given that we were using harmless chemicals
to do harmless experiments. I wish this had been around, and it had been
required reading--I would have all about that safety gear.

------
fidget

        Takeaways:
        Don't store strong chemicals in your bedroom
    

Some of these seem the wrong side of irresponsible

------
Animats
Darwin award applicant.

 _" I had made some gunpowder and had some sitting on an outside table. I was
experimenting with fuse design and was burning a fuse 6 feet or so away."_

 _" I bought some H2SO4 and used most of it immediately. Unfortunately the
original plastic bottle didn't fit in my cabinet. So I transferred the
contents to a couple of small plastic bottles. Finally, the cabinet was
temporarily blocked so I decided to temporarily store them on a shelf next to
my bed."_

 _" I had a few hundred mL of acetone and H2SO4 waste stored in a glass peanut
butter jar."_

~~~
CamperBob2
Yeah, I enjoy occasional shenanigans with dangerous items and substances as
much as the next nerd, but this guy is just plain reckless. He needs to find
something else to do, preferably before something tragic occurs.

He's incredibly bright (the X-ray machine with the 2D positioner is just plain
brilliant) but he just doesn't seem to think far enough ahead.

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brandmeyer
That 450VDC electrolytic capacitor wasn't the worst failure I've experienced
with such a device. I had one let go about 3 meters away from me. It sounded
like a shotgun had gone off, and left my ears ringing for a few minutes. There
wasn't anything left but the terminals.

~~~
HankB99
Reminds me of a similar situation. We were working on a device powered by what
looked like a 6 pack of 16 Oz cans caps charged to 500V. SCRs controlled the
discharge of the capacitors into the device and caps were charged in opposite
polarity so that the device could deliver current in opposite polarity
depending on which way the mechanism was to move. There was a flaw in the
logic that controlled the SCRs and in some circumstances both directions were
on resulting in a direct short between the two banks of caps, discharging all
stored energy in a fraction of a second (about 300 ms IIRC) That resulted in
catastrophic failure of the SCR which propelled pieces of casing across the
room and left my ears ringing.

I asked that a cardboard box blast shield be placed over the H/W before
participating in further tests.

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JabavuAdams
Fantastic! I love reading accident reports, for some reason. There's so much
practical knowledge contained in them.

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AnimalMuppet
> Think twice before "stop, drop, and roll" as the floor may be on fire

Wow. Just... wow.

------
mschuster91
In school we had a public display exhibition - a series of LEDs mounted on
PCBs with shifters. Like, you put in a color at the first PCB and pressed the
"shift" button and the color would shift through the chain, the color of the
last PCB in the chain would vanish. Each PCB had a capacitor on the 12V supply
rail.

So, I needed to swap the PSU because we planned to add more of them, and I
plugged it out - and cut the supply cable with a scissor. Twelve capacitors
blew out (I believe because the ICs turned off the power of the LEDs before
the caps were discharged, they were ridiculously huge anyways)... right in the
middle of school day, and a week before there was some retard running amok and
killing students.

tl; dr: Shorted 12 caps, huge explosion sound, peoples panicked and thought of
a school shooting.

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weaksauce
I'm almost glad I didn't pay more attention in chemistry class because I'm
sure I'd do some of these blunders.

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rdtsc
> This released profuse magic smoke and severely damaged the power supply.

Magic smoke needs a magic fume hood or being outside ;-) I can't say for sure,
but I would err guessing a lot of smoke coming out of exploding or burning
electronic components is not good for you.

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jtchang
How is this dude not dead yet?!

~~~
tajen
This dude is really passionate. I don't know anyone who did chemistry for fun,
let alone had any budget and enough parent leniency to do it before 18yo. As
he grows up you notice he talks more and more about security gear.

I don't know how someone can get into chemistry before 18. I understand
reactions that are presented to me, but how do you get the initiative of
trying something new? How can I be confident those are the _only_ reactions
that happen? OP has only produced H2S by mistake a few times in his life, far
fewer than I'd expect anyone experimenting to produce unexpected chemicals.

~~~
JabavuAdams
> I understand reactions that are presented to me, but how do you get the
> initiative of trying something new?

This is what kids do naturally, before they know any better. A lot of kids
experiment with chemistry. The trick is keeping them alive and unmangled until
they develop a respect for what they're working with.

~~~
brandmeyer
In my attempt not to drill my young kids' exploration out of them, I tell them
that "X is a tool, not a toy!", for values of X like knives, fire, light
sockets, etc. And then promptly talk about how to use them :)

