hmmm. tricky. It's all done by direct debit thing, I'd need to find a bit
of paper.
Mind, they recently screwed around with the distribution network. Luckily,
the place not too far away continues to get them as a customer and swaps
them out with their customers, even though they're not a full-blown agent
any more.
--
Austin Shackles. www.ddol-las.net my opinions are just that
Travel The Galaxy! Meet Fascinating Life Forms...
I'd also be very interested to know of a cheaper supplier of full sized
Oxy/Acetylene bottles than BOC and without resorting to any complicated
Direct Debit arrangement etc
Are there such suppliers?
Brad
On or around Mon, 1 Sep 2008 13:54:15 +0100, "BRAD"
dunno. Best bet would be find yer nearest large steel molishing type place
and see if you can do a deal.
Air Products have fewer hoops to jump through, but still want bottle rental
by DD, I think.
I suppose technically you could buy a set of bottles, and then exchange
them.
--
Austin Shackles. www.ddol-las.net my opinions are just that
Travel The Galaxy! Meet Fascinating Life Forms...
Not wishing to teach my grandmother to suck eggs here, but I can vouch
for what others have said about the dangers of pressurising acetylyne
even a relatively little bit. A regular Guy Fawkes night trick was to
fill a condom with oxy-acetylne mix which then makes a great bang when
the bonfire's lit. Then on about the 3rd occasion my mate did this,
the gas detonated whilst he was filling it - what initially appeared
to a Laurel and Hardy moment was actually rather more serious and he'd
perforated both ear drums. Although his hearing did return somewhat,
some damage was permanent and, for instance, he could no longer go
scuba diving. This is only at balloon pressure remember. There was a
view that the condom lubricant was a contributory factor, so
presumably risk can be reduced by keeping a carbide generator very
clean and oil free. I've also heard of the gas evolving from "spent"
carbide exploding when being carried in a sealed container - an ammo
can used for carrying stuff in caves. It went off when banged on a
rock, slightly injuring the hand of the bloke carrying it. He said
he'd have been hurt rather worse if the rock hadn't been shielding him
from it when it went off. (carbide lights used to be used for caving)
Hywel
Oxy-acetylene mix is even more dangerous than acetylene - by far!
The ignition energy required is less than 1/10, maybe 1/100th of the
ignition energy of aceteylene itself - which is still low.
Acetylene/oxygen mixes can detonate at 1/10th atmospheric pressure, or less.
Pure acetylene by itself is not just dangerous by detonation, which
requires maybe 18 psia - it also deflagrates (burns slowly - but slowly
can be anything from very slow to bl**dy fast indeed!) at lower
pressures than pure acetylene, including less than atmospheric pressure.
Then on about the 3rd occasion my mate did this,
:(
I have holes in both my eardrums - I can (or could - they seem to be
blocked now) blow bubbles from them in the bath. Maybe they've regrown,
or filed with wax, but loud bangs do that.
This is only at balloon pressure remember. There was a
No.
Cleanliness and oil-freeness are requirements - but as I said above, the
ignition energy of acetylene/oxygen mixes is very low indeed.
The acetylene/oxygen ignition energy is far less than the ignition
energy of the condom lubricant in oxygen, probably ooms less - but then
perhaps even a bursting balloon might give enough energy to ignite an
oxygen/acetylene mix.
Not kidding.
I've also heard of the gas evolving from "spent"
Not surprising. Spent carbide is dangerous, and will give off acetylene
for a good while.
Still are, occasionally.
I did sanity-check this, but I'm so drunk right now that I'm not sure of
my own sanity -
- and I'm not infallible anyway, as my lack of fingers will attest.
-- Peter Fairbrother
Y'rright of course. Let me rephrase my reply, hoping this is clearer:
hyweldavies wrote:
> Not wishing to teach my grandmother to suck eggs here, but I can vouch
> for what others have said about the dangers of pressurising acetylene
> even a relatively little bit. A regular Guy Fawkes night trick was to
> fill a condom with oxy-acetylene mix which then makes a great bang when
> the bonfire's lit.
Oxy-acetylene mix is even more dangerous than acetylene - by far!
The ignition energy required is less than 1/10, maybe 1/100th of the
ignition energy of acetylene itself - which is still low.
Acetylene/oxygen mixes can detonate at 1/10th atmospheric pressure, or
less. Acetylene/air mixes can explode below atmospheric pressure too,
which is why it's important to flush acetylene hoses immediately before use.
Acetylene without oxygen can not only detonate, which only takes place
at 15 psia or more, but it can also deflagrate at any pressure.
(A deflagration is when the reaction front moves slower [1] than the
speed of sound in the material - if it moves above the speed of sound
it's a detonation, that's the difference between a detonation and a
deflagration. When a reaction front moves faster than the speed of sound
some of the energy goes into making shock waves, which can be very damaging.
[1] for acetylene slower can be anything from very slow to very fast
indeed!)
Most flashbacks in acetylene hoses are deflagrations, not detonations.
Sometimes acetylene burns inside the torch without oxygen, and that's a
deflagration too - but the occasional "pop" may be a detonation of
oxygen/acetylene mix.
Another example of a deflagration is in the regulator of an acetylene
cylinder - this *always* happens to some extent when acetylene is used.
Acetylene regulator passages are made small to limit the volume and thus
lower the rate of reaction so that only a small proportion of the
acetylene decomposes, and to ensure the deflagration does not become a
detonation.
So don't use anything except a proper regulator designed for acetylene
with acetylene!
Then on about the 3rd occasion my mate did this,
> the gas detonated whilst he was filling it - what initially appeared
> to a Laurel and Hardy moment was actually rather more serious and he'd
> perforated both ear drums. Although his hearing did return somewhat,
> some damage was permanent and, for instance, he could no longer go
> scuba diving.
:(
I have holes in both my eardrums - I can (or could - they seem to be
blocked now) blow bubbles from them in the bath. Maybe they've regrown,
or filled with wax, but loud bangs do that.
This is only at balloon pressure remember. There was a
> view that the condom lubricant was a contributory factor, so
> presumably risk can be reduced by keeping a carbide generator very
> clean and oil free.
Not my view. As I said above, the ignition energy of acetylene/oxygen
mixes is very low indeed, far less than the ignition energy of the
condom lubricant in oxygen, probably OOMs [2] less - but then perhaps
even a bursting balloon might give enough energy to ignite an
oxygen/acetylene mix.
Not kidding.
[2] orders of magnitude
I've also heard of the gas evolving from "spent"
> carbide exploding when being carried in a sealed container - an ammo
> can used for carrying stuff in caves. It went off when banged on a
> rock, slightly injuring the hand of the bloke carrying it. He said
> he'd have been hurt rather worse if the rock hadn't been shielding him
> from it when it went off.
Not surprising. Spent carbide is dangerous, and will give off acetylene
for a good while. A polythene bag should be okay, but not a metal
container in which the gas pressure can rise.
> (carbide lights used to be used for caving)
Still are, occasionally.
> Hywel
-- Peter Fairbrother
Also used at party time, balloon with OA inside, nitrogen tri-iodide
outside.
The other use of welding kit on Guy Fawkes night is handing out old,
damp arc welding rods to the youngsters, telling them that they are
sparklers and watching their attempts to obtain ignition from the
bonfire. Once the kidz have gained a nice cherry-red colour we give
them real sparklers, otherwise it would be unkind.
<snip>
Where do you buy driplamp carbide these days? Halfords no longer
stock it. Wouldn't mind a bit to play with, for old times sake.
Regards,
David P.
I have available an unopened sealed canister of carbide -
stated average contents - 6.25Kg.
Should be enough for a spectacular bonfire night if
anyone is interested.
Jim
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