Clear cases, case windows - fire hazards?

[CBFalconer]

.... snip ...


What kind of idiots allow lit candles in their house, except
in a blackout?

Apparently you don't associate with women

 

[Strontium]

-
CBFalconer stood up at show-n-tell, in (e-mail address removed), and
said:

Apparently you don't associate with women

You stole the words, from my mouth I remember that my last ex wanted
candles, all of the time.... Scared the shit out of me, as I don't like
fire hazards (ironically, lol).

 

[kony]

Why do you assume that electrical fires need high voltage? High
currents are more likely to start and sustain arcs and melt wires.

Not "need", but the occurance is higher. High currents are not more
likely to start arcs, an arc is almost solely dependant on the
voltage. Of course melting wires would be a problem... but, the
solution is to FIX the problem, not make everything around (melty
wires) be inflammable but to replace the bad components.

The PSU is in a metal box, but it carries current outside, where it's
converted to higher current for the CPU and maybe the AGP card, and
those parts aren't shielded against the window or case.

Heat internal to a part, and sustained extreme heat that produces
combusion outside that part, are two different things. If a part
stayed at a temp high enough to cause combustion for long enough to do
so, it would be destroyed already, either open circuit so it ceased to
heat up, or short that causes power supply to shut off... if you
think your power supply won't, it needs replaced.

I've never even seen an installed copper heatsink.

Hmm. They aren't all that uncommon. You really think a computer is
going to catch it's plastic side-panel on fire if the heatsink fell
off? Get such a heatsink, see if you can make it happen... cut some
wires and such, install some already-vented caps, whatever... see if
there's any possible damage you can do to get a fire going with ONLY
the parts found in a PC. Be sure to use a halfway decent power supply
since I metioned that already. Until you can deliberately create a
case fire that ignites the side panel, in such a way that it's
semi-reasonable that a chain of events could produce same result, I'm
not going to buy the argument that it's likely to happen, that it's a
reasonable consideration compared to any other risks in life.

I'm not a lawyer and have never even been a plaintiff.

.... yet something is making you obsess abou this... Perhaps you're
right, but you have no argument that (at least I) find convincing.

I mentioned transistors burning out from them.

But did they catch the case on fire? Having them overheat and fail is
quite a bit different than igniting something.

What kind of enclosures were they in?

It would seem you're drawing the wrong conclusion here, the power
supply IS going to be the cause or major contributor to the fire. The
power density isn't high enough for any other part to ignite UNLESS
the power supply isn't shutting off in an overcurrent situation.
Again, the focus on plastic side-panels is wasted effort, the power
supply needs replaced.

If a hazard can be prevented cheaply and simply, why not prevent it?

it's called "freedom". People don't like others deciding what's best
for them, especially in situations where there is an overstated
minimal risk. You haven't yet shown any evidence that this hazard
even exists yet, just a theory about a chain of events. Until you
replicate that chain of events and prove the theory, it's not worth
acting on. Perhaps you're right, will be a pioneer in creating safe
computer cases, but first you need evidence, not argument.

What kind of idiots allow lit candles in their house, except in a
blackout?

Outlaw candles then?



Dave

 

[larrymoencurly]

Apparently you don't associate with women

I associate with one whose brother is a fire fighter.

 

[larrymoencurly]

Not "need", but the occurance is higher. High currents are not more
likely to start arcs, an arc is almost solely dependant on the
voltage. Of course melting wires would be a problem... but, the
solution is to FIX the problem, not make everything around (melty
wires) be inflammable but to replace the bad components.

But many safety standards, private and government, do require less
flammable components in case problems like that happen.

The PSU is in a metal box, but it carries current outside, where it's
converted to higher current for the CPU and maybe the AGP card, and
those parts aren't shielded against the window or case.

Heat internal to a part, and sustained extreme heat that produces
combusion outside that part, are two different things. If a part
stayed at a temp high enough to cause combustion for long enough to do
so, it would be destroyed already, either open circuit so it ceased to
heat up, or short that causes power supply to shut off... if you
think your power supply won't, it needs replaced.

Then how do you explain all those TV fires that managed to melt the
cabinets?

You really think a computer is going to catch it's plastic
side-panel on fire if the heatsink fell off?

Until you can deliberately create a case fire that ignites the
side panel, in such a way that it's semi-reasonable that a
chain of events could produce same result, I'm not going to
buy the argument that it's likely to happen, that it's a
reasonable consideration compared to any other risks in life.

Again, why did so many old TVs manage to burn down homes from fires
started inside those TVs? Computers and TVs both have exposed
high-power, high-current circuitry inside. Even a model of baby
monitor intercoms made of regular plastic caused some fires (not much
power there, probably no high voltage but the 120VAC).

I mentioned transistors burning out from them.

But did they catch the case on fire? Having them overheat and fail
is quite a bit different than igniting something.

Those transistors usually don't have big heatsinks, usually nothing
more than some copper on the circuit board, and they can get very hot
very quickly.

I've seen power supplies they exploded in... makes a mess, but there
was no fire.

It would seem you're drawing the wrong conclusion here, the power
supply IS going to be the cause or major contributor to the fire. The
power density isn't high enough for any other part to ignite UNLESS
the power supply isn't shutting off in an overcurrent situation.
Again, the focus on plastic side-panels is wasted effort, the power
supply needs replaced.

That's dodging the question, and I asked about those power supplies
because I wanted to know if their enclosures helped prevent further
damage.

it's called "freedom". People don't like others deciding what's best
for them, especially in situations where there is an overstated
minimal risk.

Sounds like a kneejerk libertarian mindset at work, sort of like
homeowners who want to keep their shake shingles in a crowded
neighborhood. I don't know if the problem of computer fires is
minimal because why else would Apple bother with fire-resistant cases
for their computers?

This time of year the better safety message would be "watch those
candles".

Outlaw candles then?

Another kneejerk reaction.

 

[kony]

But many safety standards, private and government, do require less
flammable components in case problems like that happen.

Let start where the problem lies instead, more stringent regulations
for power supplies... some of 'em never should've been made, IMHO.

Heat internal to a part, and sustained extreme heat that produces
combusion outside that part, are two different things. If a part
stayed at a temp high enough to cause combustion for long enough to do
so, it would be destroyed already, either open circuit so it ceased to
heat up, or short that causes power supply to shut off... if you
think your power supply won't, it needs replaced.

Then how do you explain all those TV fires that managed to melt the
cabinets?

TVs do not have their power supplies, that region of the circuit, in a
metal box. TVs also generate, and have more areas using, high
voltage.

Again, why did so many old TVs manage to burn down homes from fires
started inside those TVs? Computers and TVs both have exposed
high-power, high-current circuitry inside. Even a model of baby
monitor intercoms made of regular plastic caused some fires (not much
power there, probably no high voltage but the 120VAC).

Is it a TV? I do think CRT monitors should have higher
flame-retardance than PC case windows.

"Power" does not matter, a high voltage creates an arc that a power
supply may be able to sustain, but with a low-voltage arc, it's low
resistance, high current, making the power supply shut down. Try it-
Short a power supply wire, trying to cause a fire with an arc. Even
with this intentional act it's not likley you can get a fire started
IF the power supply has overcurrent protection, and/or undervoltage
protection.

Those transistors usually don't have big heatsinks, usually nothing
more than some copper on the circuit board, and they can get very hot
very quickly.

Yes, so? Enough with the theories, take a power supply, directly wire
it to a mosfet, and see if it catches anything on fire... we could
play "what if" all day but at some point it has to be confirmed to
actually be a problem. Motherboard regulators DO fail, no fire. I've
even seen them bust open or become desoldered and slide down the
board, but the system didn't ignite.

That's dodging the question, and I asked about those power supplies
because I wanted to know if their enclosures helped prevent further
damage.

It's not dodging a question to skip the obvious answer (which we both
knew was "metal") and move on to the relevant items.

Their housings don't just help, they work. The whole power supply, as
a unit, works when properly designed.

Enough speculation- get a PC, and try to set it ablaze using ONLY the
components in it, in a way it could possibly fail. Even add a few
wires if you like, some extra solder here and there.... show us it'll
catch on fire even in one scenario, even an unlikely one.

Sounds like a kneejerk libertarian mindset at work, sort of like
homeowners who want to keep their shake shingles in a crowded
neighborhood. I don't know if the problem of computer fires is
minimal because why else would Apple bother with fire-resistant cases
for their computers?

Because Apple likes to use these types of things to market their
goods, knowing they're fighting a loosing battle against PCs they look
for any angle possible to keep afloat. Also since they're making
unique cases anyway, they can spec what they want the case made out
of. Why not ask them if they had a problem with their systems
bursting into flames with the previous case materials?

Another kneejerk reaction.

That's a good way to describe this whole thread.

You're wasting our time by posting this without any facts or testing,
just random speculation... Go get some parts, outline the testing
procedure you're going to do, in case anyone has feedback about the
validity of it, then prove your theory. If you have exact details of
how you did (what) to create a fire in (X) region, where it spread to
result in a clear case window being a problem, then present that data!
We really like data, and pictures, etc... put up a website detailing
all your testing else you just seem fixedated and paranoid for no good
reason.


Dave

 

[jeffc]

I've heard that almost any plastic with a fairly low melting point can
easily burn like crazy, unless made with certain chemical additives.
I have a sheet of polycarbonate, a plastic that can be used in ovens
up to about 400F, but it has warnings all over saying that even though
it's the least combustible glazing plastic it will ignite if exposed
to sources of heat above 800F.

That rules my computer out. It really blazes when I'm in an intense Unreal
deathmatch with all graphics features maxed!

 

[Manny]

I've heard that almost any plastic with a fairly low
melting point can easily burn like crazy, unless made
with certain chemical additives.

It's mostly those chemical additives, in the wiring, the
circuit board resin, and the sockets, that keep a flammable
plastic case from burning down the house, and the standard
for TV fire resistance was adopted before the additives
became uncommon for those components, so TV cases are
highly fire resistant. Those chemicals deserve far more
appreciation for their contribution to safety than most
people realize, and because of them, I wouldn't worry about
a plastic case, but I'd still prefer an all-metal one.

 

[AJ]

The only reason I bought a case with a window in it was because it was
$10 after rebate, but I put in a panel of solid aluminum.

Better off replacing the vinyl dryer hose with metal. Since in many
areas that's the number one cause of house fires.

 

[Erez Volach]

Better off replacing the vinyl dryer hose with metal. Since in many
areas that's the number one cause of house fires.

Reference to "vinyl" is usually common namaing of poly vinyl chloride, which
is one of the most inherently fire-retrading polymers. Sure, in its
plasticized compound, it is not as fire resistant, but it would never burn
as readily as PP, HDPE, nylon, polystyrene or polyurethane. And it is the
most easily polymer to make flame retarding, with simple addition of a
synegic Sb32O3, reacting with the Cl, as opposed to other plastics which
require addition of Br compounds (and Sb2O3) for the same effectiveness.
ALL registered and regulated housings and cases are flame retarded, for the
whole electric and electronic industry (power sockets, cords, appliances, tv
sets, computer parts, electronics, even the individual PCB of add-on cards
and motherboards). The most common standard de-facto is UL(tm) 94-V0 (some
times V1 is allowed for certain usages)
heck, even the mouse is usually made of flame retarded High Impact Poly
Styrene all those housings which turn yellow after a year or more ?
probably HIPS with bromine compounds (now many produce grey colored to
overcome this tendancy). There are non-halogen options, which some
legistlators prefer (geography plays a big role here), based on Phosphate
compounds or use of many fillers such as Aluminum tri hydrate, MgOH etc.

 

[AJ]

Reference to "vinyl" is usually common namaing of poly vinyl chloride, which
is one of the most inherently fire-retrading polymers........................................

When it is brittle to the touch and filled with lint it can light up
like a flare.

 

[Erez Volach]

polymers........................................

When it is brittle to the touch and filled with lint it can light up
like a flare.

When it is brittle, it means the plasticizer has migrated out one way or
another (leaching, blooming, surface migration, plate-out, evaporation -
whatever you name it), and the polymer is back to original state of not
supporting fire (when flame source is removed). Having said that, lint will
burn, for sure. If there is enough oxygen around, most fibers that
accumulate as lint are readily combustible.
This is gone slightly off-topic. I don't consider the whole field of flame
retardancy in plastics and fire safety in ocmputer system to be off topic,
which is why i posted in the first plcae, just this specific thread has
drifted...
E.V