Back to Ganoksin | FAQ | Contact

Still more torch questions


#1

Regarding acetylene tank on its side and acetylene getting into
valve etc.

BEFORE attaching any tank (Oxygen, acetyelene or whatever) to its
regulator or other equipment, I was taught that it is good practice
to open the valve on the tank and allow a short, sharp blast to
escape. This will blow out any dust, debris, water, dead spiders
or whatever might be inappropriately lurking in the recesses of the
valve. Then whatever it is doesn’t get a chance to get blown into
your delicate apparatus.

It goes without saying that you shouldn’t do this while smoking or
where any unwanted accidents might result.

Marty in Victoria


#2

If an acetylene cylinder is transported on its side it should be
allowed to stand upright for at least one hour before it is used.
This allows the acetone (acetylene is dissolved in acetone to make
it more stable) to settle so it won’t come out the valve when
opened.

Ed Howard
G-TEC Natural Gas Systems
www.safe-t-gas.com


#3
If an acetylene cylinder is transported on its side it should be
allowed to stand upright for at least one hour before it is used.
This allows the acetone (acetylene is dissolved in acetone to make
it more stable) to settle so it won't come out the valve when
opened.

I would like to understand this further, please. Acetone is
dissolved into the acetylene, but later separates and settles to the
bottom of the tank, is that what you’re saying? Thank you.

James in SoFl


#4

As an addendum to what Marty in Victoria ( beautiful place that)
said, the short sharp blast will keep stuff out of your delicate
tools but, please, do it with the valve pointed away from you or
anyone else. The goodies you’re blowing out have become projectiles
that will fly a great distance and everyone I know wants to keep
their eyeballs intact.

Mike


#5
    If an acetylene cylinder is transported on its side it should
be allowed to stand upright for at least one hour before it is
used. This allows the acetone (acetylene is dissolved in acetone to
make it more stable) to settle so it won't come out the valve when
opened. 

Acetylene is very unstable and dangerous compressed above 15 psi.
This is why the Acetylene regulators usually have a red line at 15
psi. When Acetylene is dissolved in Acetone it can be pressurized to
a greater pressure, allowing more gas to be stored in the cylinder.
Inside of the cylinder is a honeycomb of some type of material
(ceramic?) If the Acetone isn’t allowed to settle back down into the
tank there will be spits and pops from the torch as the Acetone comes
out of the torch and burns. If an extreme amount of Acetone was lost
the potential for a serious instability of the Acetylene exists. Hope
this clarifies things.

Dan Wellman


#6

From:
bocindustrial.co.uk/product_product_data_sheets/acetylene.asp

  *  Acetylene cylinders differ from other gas cylinders in that
  they contain a porous filler material/mass, and a solvent in
  which the acetylene is dissolved. 

  * If acetylene were to be stored as a compressed gas, in the
  same way as other gases it would be very unstable and could
  decompose explosively. 

  * For this reason, it is dissolved in the solvent acetone,
  which allows greater quantities of the gas to be stored at a
  lower pressure in a safe manner. 

  * The porous mass acts a stabiliser, quenching any
  decomposition in the cylinder. 

  *  If a cylinder has been transported horizontally, stand it
  upright for a minimum of 1 hour prior to use. 

  * This will allow the acetone to evenly re-distribute within
  the cylinder and prevent acetone being carried in to the flame
  causing a 'flame thrower' effect. 

There is other of interest at this URL. BOC is a large
supplier of Gasses for industry both in the UK and Canada.

Two points they also mention which is worth remembering is:

Acetylene can ignite and burn instantly from a spark or piece of hot
metal and can form explosive acetylide compounds with some metals,
most notably, copper, silver and mercury. However copper alloys
containing less than 65% copper and silver solder containing less
than 43% silver are considered safe. (Kay’s note: this is with pure
unburning gas and the metal, not a torch flame)

Hoses used with acetylene are coloured red and are designed to
resist acetone. For this reason other fuel gas hoses must not be use


#7
the short sharp blast will keep stuff out of your delicate tools
but, please, do it with the valve pointed away from you or anyone
else. 

or with oxygen, pointed away from anything oily. many years ago, a
jeweler here, in phoenix az., burnt his store down by the oxygen
blast hitting the oil stones on his bench. appatrently, the oxygen,
hitting the oil stone became explosive!


#8

In its pure form acetylene is unstable and if not handled properly
can rapidly decompose, i.e. explode. Dissolving acetylene in acetone
for storage in a cylinder makes acetylene stable and safe to use as
long as certain conditions are met. It cannot be withdrawn at higher
than 15 psi, you cannot withdraw more than 1/7th the remaining
contents of a cylinder per hour and you cannot shock the cylinder
(hitting it with a hammer or, more likely, dropping a cylinder).

Again, dissolving acetylene in acetone makes it safe to use in
cylinders - when you open the valve acetylene dissociates from the
acetone and goes to your torch. In effect, it is boiling off the top
of the acetone and going out the valve. When the cylinder has been on
its side for a while then turned upright and used, you can get
acetone coming out the valve along with the acetylene.

You can learn more about acetylene by reading a Material Safety Data
Sheet (MSDS) such as here http://www.iigas.com/acetylene_msds.htm,
though there are many versions of this available on the Internet.

Even when handled according to accepted safety practices acetylene
still is a dangerous fuel - note on the MSDS that it is flammable in
a mixture with air between 2% to 80% and can be ignited with a static
electricity spark.

I’m interested in this because my company manufactures a natural gas
pressure booster that elevates utility natural gas pressure for
torch work; we replace acetylene and other fuels with high pressure
natural gas, right from the utility natural gas line. You can find
out more about the safety and performance benefits of high-pressure
natural gas at www.safe-t-gas.com.

Ed Howard
G-TEC Natural Gas Systems
www.safe-t-gas.com


#9

Hi James,

I would like to understand this further, please. Acetone is
dissolved into the acetylene, but later separates and settles to
the bottom of the tank, is that what you're saying?

The acetylene is dissolved in the acetone.

Because everything in the tank is under pressure, if the tank is
lying on it’s side or in any position with the valve lower than the
tank, the acetone (with dissolved acetylene) will be forced out the
valve if it’s opened. In order to prevent the acetone from be
expelled, the tank should be returned to a full upright position &
allowed to stand in that position for a short time before the valve
is opened.

This will give the acetone a chance to seek a level lower than the
valve.

Dave


#10

I’ve been waiting for someone to identify the "gray spongy stuff"
that fills nearly 100% of the interior of an acetylene cylinder,
but since no one has, I thought I’d throw this in…

My first “real” job was as a traveling salesman for Selpac SE,
selling Sherwood high pressure compressed gas valves; (oxygen,
nitrogen, argon, nitrous oxide, etc,) as well as propane and
acetylene valves. I sold primarily to the welding industry in the
SE, USA. If you check the valves on your tanks you stand a better
than a 50/50 chance of having a Sherwood valve on one of them.

One of our accounts, Union Carbide, was a major acetylene
manufacturer/filler. Right after I was hired on, my boss took me way
back to the back of one of the Union Carbide plants for an
education from an OLD-timer that he knew. The old fellow began his
lecture by telling me that the gas is manufactured from the
mineral, carbide; a rock. This is the stuff that is mixed with
water to create the flame that was (and sometimes still is) used to
illuminate the old miners’ and spelunkers’ helmets. I was told that
acetylene was SO unstable that if it were not mixed with acetone
and cushioned by the “gray spongy stuff” in the cylinder, that as
little as a small coffee cup of the pure acetylene, if dropped on
the floor would have exploded and killed the 3 of us outright and
that a whole cylinder’s worth would have leveled the 50’ x 150’
plant that we were standing in (that always sounded a bit
far-fetched to me, but I was never inclined to experiment!). Then
he went on to explain that the “gray spongy stuff” that filled the
bottle was, in fact, ASBESTOS!!! They actually had an in-house
supply of a ground asbestos slurry which they injected into new
cylinders then baked into a solid mass. SCARY stuff!!! I can still
remember that little educational session to this day!

That was over 25 years ago and they may not be using asbestos in
acetylene cylinders anymore, but I wouldn’t bet on it. This is just
another good reason why suppliers should only EXCHANGE acetylene
cylinders. It is set up that way so that only qualified personnel
in a suitable facility are responsible for filling/maintaining what
is not only essentially a bomb, but is also a MAJOR carcinogen!!!

Having said all that, keep in mind that gas
welding/brazing/soldering has a LONG (over 150 years) and
essentially SAFE history. If a person of reasonable intelligence
gets a little training and uses simple common sense they should
have nothing to worry about.

As for laying an acetylene cylinder on its side, its not a really
good practice, but as long as you allow plenty of time for the
contents to settle (overnight, to err on the long side!), it
shouldn’t ever cause you any problems.

Personally, I prefer propane (LPG), because it is cheaper, so much
cleaner to use, and is sold in 20 lbs. tanks nearly everywhere.
Propane, though, has its own set of limitations and drawbacks!!
:wink:

Steve
Steve’s Place
Jewelry Repair
While-U-Watch


#11

Hi James,

    I would like to understand this further, please. Acetone is
dissolved into the acetylene, but later separates and settles to
the bottom of the tank, is that what you're saying? 

The acyetlyene is dissolved in the acetone. Think of the carbon
dioxide dissolved in a bottle of soda (think “Pepsi-cola”). So long as
the cap is on the bottle, the gas (CO2) remains dissolved in the
liquid, because it is under pressure. Once you open the cap, the
pressure inside the bottle drops and the gas is released from being
dissolved, and fizzes out. If the soda bottle is upright, the gas
leaks out. If it is laying on its side, the gas forces the liquid out.
In simplified terms, the same thing happens inside of an Acetlyene
tank.

-AL


#12

At the risk of crossing the line on advertising let me make you
aware of a new natural gas torch booster that elevates standard
utility natural gas pressure up to 25 psi, so it can be used for
casting platinum, all karats of gold, as well as for soldering and
brazing torchwork.

We exhibited the system at Rio Grande’s Catalog In Motion program
and many people asked why they hadn’t seen anything about this on
Orchid. I see discussion about handling and using different fuel
gases so here’s one more option.

There are many choices for fuel gas but natural gas is cheap, clean
and safe - it does a great job if you can get enough pressure. While
a Little Torch works well with standard utility gas other torches and
some applications may need higher pressure and this is what the
natural gas torch booster does. The system is CSA Certified and safe
to install in a home studio. It eliminates fuel gas cylinders…you
continue to use oxygen the same way as you do now.

If interested there is more here www.safe-t-gas.com , or
on page 335 of the Rio Grande Tools and Equipment 2005 catalog.

Ed Howard
G-TEC Natural Gas Systems
ehoward@gas-tec.com


#13

Hi all,

As it was taught to me. Acetylene is dissolved into acetone. To make
stable. The tanks are filled with a buffer either pith or asbestos
to act as a shock absorber.

Try rapping the side of a Acetylene tank you will get a thud. Then
rap a Oxygen tank and it will ring like a bell. They are hollow. The
acetone and the pith separate the acetylene molecules. When you open
the valve the effervesces off to supply you with acetylene(like a
bottle of pop with bubble rising to top.) The idea here is not to
let off to much into the regulator. Over 15psi is explosive. Really.
No kidding. In welding classes they love to show you the bad results
in the form of exploded valves. My last suggestion is to err on the
side of the angels and not take chances.

Jim Zimmerman
@Jim_Zimmerman2
http://www.handengravingcanada.com