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Acetylene tank and cold weather


#1

Howdy,

I vaguely remember being told by a guy who works at my local gas
supply company that acetylene will become a liquid in cold weather.
That the tank can appear to not have any gas in it but actually all
the gas has become liquid and has pooled at the bottom of the tank.
Hmmm… I know I’m missing something to this explanation.

Anyways, it got down to the low 30s last nite and I didn’t have the
heat on at all. I live in a brick house with bad windows and
virtually no insulation so it gets very cold when the heat is not on.
When I went down to my metalsmithing work area in the basement where
I keep my oxy/acetylene tanks, I noticed I couldn’t get my acetylene
up to 5 psi. Maybe 2 psi. The flame I did get would eventually putter
out after a couple minutes. My tank is at least half full and I have
detected no leaks. I’m convinced that it is due to the cold weather
and the acetylene.

Has anyone run into this problem with acetylene during the cold
months? I can’t afford to heat the basement just so I can use
acetylene down there.

Thanks,
Chris


#2
....acetylene will become a liquid in cold weather. 

Well, Chris, my acetylene tank is always outdoors (inside a big
plastic garbage can) all winter long – I have never had any problem
with it. I must admit that I usually don’t do any outdoor soldering
after the daytime weather goes below the 40s, because my hands get
too cold. But the tank itself has certainly gotten below that.

Judy Bjorkman (upstate New York)


#3
Has anyone run into this problem with acetylene during the cold
months? I can't afford to heat the basement just so I can use
acetylene down there. 

Yes, it’s a known issue with acetylene. In fact, it’s not recommended
to try to use a large torch with a partially discharged tank in very
cold weather.

Take the following discussion thread, for example:

You don’t really need to heat the basement, but storing the tank out
of direct contact with the cold concrete (a chunk of plywood might
be enough) cant’ hurt.

Ron Charlotte – Gainesville, FL


#4

Chris,

Maybe a rather vague memory :slight_smile:

I live in Vermont where sub zero F is not uncommon. Lots of welding
company pickups with o2/acet tanks in the back, even I am not nutz
enough to heat an acet tank.

Propane is a different story. Usually a prop/butane blend for the
season. A summer blend could cause problems in the dead of winter,
butane is cheaper but does liquify at much higher temps. As I recall
even straight propane is rather useless below -40.

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand


#5

The problem is that as the acetone gets older and ages it is less
efficient at allowing the acetylene to dissolve out of it. In very
cold weather old acetone ( with contaminants) can become almost like
jelly

In the far north (read Yukon where -50 is not unknown for a few
weeks each winter) what they do on utility service trucks is wrap
heater hose to circulate hot antifreeze around the tanks and
insulation to warm them.

At the low flow rates that a Jewelers torch requires it should not
be a problem ever. Sometime look at the orifice size on a large
cutting torch and compare it to your tip… Major difference. Heck
the really big cutting torches you have to gang up Acetylene
cylinders in a manifold because even at room temperature the
acetylene cannot diffuse out of the acetone fast enough to supply
these torches.

So to summarize, yes it can be a problem at -30 for someone using A
LARGE torch, but not for you

Kay

PS and it is also normal for that full tank of oxygen that read 2200
LBS to read a whole lot less at -30, that is normal too.


#6

Hiya,

Here is basic refrigeration 101.

Releasing gas from a high pressure to low pressure environment is
the basis of refrigeration equipment - it absorbs a lot of heat.
Likewise a change of state from liquid to gas involves absorbing
many, many more calories than merely changing pressure from high to
low while remaining in same state. This cooling effect is so
pronounced that the valve or regulators leading from your acetylene
tank could get so cold that they freeze the acetylene passing
through and thus restrict the flow.

A very similar example of this happened to me when was cook on a
schooner in the Caribbean Sea years ago. We had propane tanks stored
on deck in the blazing hot sun and I was below in the galley with
all burners going on my stove when the gas flow to the stove began
to diminish noticeably and finally I could barely keep one burner
alight. I knew the tanks had been freshly re-filled so I was
puzzled. When I went on deck I could see that despite the heat and
the sun, the valve of the propane tank was covered with a thick
coating of crisp, white ice, condensed and frozen moisture from the
surrounding air. The propane had frozen inside the valve and blocked
its own passage. There was nothing to do but to turn off the stove,
let the valves thaw out and resume cooking, using fewer burners.

I missed the beginning of this thread, but I imagine if you are
using a relatively large torch, ergo large gas flow, and starting
with an already-cold tank of liquified acetylene, then you could be
creating a similar self-refrigerating condition at your tank’s
valve.

Let us know how things work out.
Good luck.
Marty in Victoria BC where life is a gas!


#7

Acetylene cylinders have a spongy layer in the bottom that hold a
liquid (used to be water but am told it is something else now)that
help keep the acetylene partially dissolved and hence regulates the
cylinder internal pressure. Now, in the days of water being in the
cylinder, that freezing would force all of the gas out of solution
and cause the regulators to rupture.

The changes to the liquid and new working pressures for the
regulators should have put an end to that problem BUT if you have
avery old oxyacet set then beware!

Nick Royall


#8

I don’t believe water was ever used to hold acetylene in these fuel
cylinders. It is soluble in water but only at 1.1 volumes of
acetylene into 1 volume of water whereas acetone can hold 25 volumes
of acetylene per 1 volume of acetone. Before the process that is
currently used with acetone and porous material filling the complete
volume of the cylinder storing acetylene gas under pressure was
considered way too dangerous as it will spontaneously explosively
decompose at elevated pressures.

There are gas generators that produced acetylene at atmospheric
pressure by reacting calcium carbide with water they were quite
common at one point in time, this may be what you were thinking
about.

James Binnion
@James_Binnion
James Binnion Metal Arts


#9

(stop the madness) As James said water was used in the generation of
Acetylene gas (miners lamps, old style caving lamps as The PC lamps
now are electric) Today acetylene is mainly manufactured by the
partial combustion of methane or appears as a side product in the
ethelyne stream from cracking of hydrocarbons. Other than in
locations were the transport and re filling of the cylinders isn’t
cost effective. Undeveloped countries, way off the grid.

The filler in the cylinders is Agamassan (aga) is a porous substrate
used to safely absorb acetylene/solvent and thus allow the
transport, storage and commercial exploitation of an otherwise
unstable gas. At one time they tried asbestos for only a couple
years, by only one or two cylinder makers. It didn’t work out all
most all of those have been accounted for and removed from service.
( the compressed gas association keeps very good records) The porous
filler fills the cylinder almost to the top, there is only a couple
of inches of free space for the acetylene to come out of the
dissolved state.

The two liquids that are used to dissolve acetylene for compressed
transport and use are Acetone and Dimethylformamide DMF a polar
(hydrophilic) Aprotic solvent.

OHSA has adjusted the rule for filling and withdrawing acetylene,
While the old standard recommended a flow rate of 1/7 of the
cylinder capacity regardless of the duration of use, the revision
has advises a flow rate of 1/10 per hour for intermittent use and
1/15 for continuous use. Unless you are a volume user this probably
will not apply.

Although the new revision only advises against transporting in
automobiles, it specifically prohibits storing acetylene cylinders
in confined spaces, such as unventilated cabinets, closets, and
drawers.

Gas Pressure(acetylene in this case)will remain almost constant at a
given temperature. As you withdraw the acetylene from the solution
in the cylinder till very little remains. If you are taking the
gauge pressure down on the acetylene cylinder to below 25psig it can
cause acetone to be withdrawn with the gas.

Following the gas laws: The combined gas law is a combination of
Boyle’s Law and Charles’s Law; hence its name. In the combined gas
law, the volume of gas is directly proportional to the absolute
temperature and inversely proportional to the pressure. Simply put
the colder the temp the lower the gas pressure, as the temp climbs
the pressure increases. So you may have more gas in the cylinder
than appears, on the gauge.

The single stage regulators can cause problems as they are
constantly adjusting to the cylinder pressure with will vary a light
bit at the tip as the regulator reacts. The two stage regulators will
maintain a very constant pressure at the torch tip. They are
recommended for use with rosebuds and very large torch tips. Along
with possible manifold system.

Most acetylene cylinders are filled to 225 pisg @70’F. PSIG is
Pounds per square inch gauge which means the pressure registered on
the gauge plus the atmospheric pressure 14.7 psi

Here are some facts about Acetylene: The explosive limits in air are
2.5-80% This is why it isn’t a good idea to transport in a closed
vehicle let alone smoke in the same vehicle.

It is lighter than air so it collets near the ceiling, if there is a
leak. It has a garlic like odorant added to it for leaks.

The MC cylinders are 10 cu ft. in capacity and weighs 7.4 pounds
full The MC stands for Motorcycle that is why the angled valve. At
one time it was the source for gas to operate the lights on
Motorcycles.

The B cylinder is 40 cu ft. in capacity and weighs 23.2 pounds full.
They are called Bus cylinders as they were used on buses and truck
back in the day.

If you transport the cylinder on its side, you must let the
acetylene gas/acetone/DMF flow back into the filler (upright)to
avoid carry over. It can cause a greenish flame, burning liquid
drips, spurting flame and other problems. The suggested times are a
minimum of the time it was on its side or 15 minutes, 30 minutes
minimum is better. Or the length of time it was on its side plus 15
minutes.

The acetone/DMF can cause damage to the regulators and hoses.

And finally Do not pipe acetylene into your house or shop using
copper tubing, pipe or fittings. Search “Copper Acetylide” it will
explain a some little mentioned Which today seem more
people are considering doing just that. After listening to the
genius down the street.


#10
And finally Do not pipe acetylene into your house or shop using
copper tubing, pipe or fittings. Search "Copper Acetylide" it will
explain a some little mentioned Which today seem more
people are considering doing just that. After listening to the
genius down the street. 

I know about copper and acetylene now. Years ago I was given the
task of plumbing Acet/O2 to 8 torches. Easy I thought, gas rated
rubber hoses.

Welding company would not sell me the hoses, insisted that copper or
black iron pipe was the only only legal way to do it. More work or
lots more work either way.

Copper installed and No craters left behind, I even re-used much of
the copper tube when the company moved. Still no craters. I must be
losing my touch :slight_smile:


#11
There are gas generators that produced acetylene at atmospheric
pressure by reacting calcium carbide with water they were quite
common at one point in time, this may be what you were thinking
about. 

The old carbide lamp on a miner’s hard hat - used them many times in
caves back in Missouri!!

Pam Chott
www.songofthephoenix.com


#12

Hi Gang,

You might want to check with your local building code or fire dept.

I many areas, it’s illegal to use copper pipe to move acetylene from
place to place. The only acceptable pipe is black iron pipe.
Galvanized pipe can’t be used either.

Dave


#13
I many areas, it's illegal to use copper pipe to move acetylene
from place to place. The only acceptable pipe is black iron pipe.
Galvanized pipe can't be used either. 

Anywhere that has building codes will forbid plumbing acetylene gas
in copper. Google copper acetylide for the the education. But in
short it is a shock sensitive explosive compound that can under the
right conditions form in pipes made from copper that are carrying
acetylene gas. Any kind of shock or vibration can set it off
resulting in serious, potentially fatal consequences.

Just don’t do it,

Jim

James Binnion
James Binnion Metal Arts


#14

Copper acetylide can form inside pipes made of copper or an alloy
with high copper content, which may result in violent explosion.
This was found to be the cause of explosions in acetylene plants, and
led to abandonment of copper as a construction material in such
plants. Generally above 67% pure copper.

It was a problem back in the day when most of the pipe/tubing and
copper fittings when made form virgin or a higher % copper then is
used now. With the increase in copper prices, and the recycling of
copper. Legally and otherwise. Plumbing supplies are made with a high
amount of other metals in the alloy mixes.

According to the CDA (Copper Development Association) www.copper.org
Copper is routinely refined to 99.98% purity (even more pure than
Ivory Soap) before it is acceptable for many electrical applications.
As any other material will alter the electrical characteristics, and
then the electrical properties of the wire. Which will cause
problems, with the wires current handling ability.

“Welding company would not sell me the hoses” well now you can buy
the hose all the hose you want. But it you tell them what you are
planning to do with it most will balk due to liability issues.
Something called “prior knowledge before the fact, or unsuitable for
use”

This is due to the high vulnerability to damage the hoses can suffer
so easily. Hoses used with acetylene must be Grade R RM or T.

The amazing thing is that there are not more accidents involving the
home/hobbyist uses of air/acetylene oxygen/acetylene torches. With
the amount of miss or people advocating the use in
classes that really and truly don’t have a clue about them.

They are safe to use, when they are used correctly. The net is
filled with people that misuse acetylene, or even vid’s of the
unfortunate few that are caught in a vehicle carrying mishap!

mjoat/glen


#15
It was a problem back in the day when most of the pipe/tubing and
copper fittings when made form virgin or a higher % copper then is
used now. With the increase in copper prices, and the recycling of
copper. Legally and otherwise. Plumbing supplies are made with a 
high amount of other metals in the alloy mixes. 

In the US the copper alloy used in virtually all plumbing is C1220
which is 99.9% copper and a tiny (about.02%) amount of phosphorous.
According to the CDA to be called copper it must be at least 99.3%
copper.

James Binnion
James Binnion Metal Arts