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Propane Safety and Torch Work


#1

The concern over soldering gases comes up quite often on Orchid, and
it is a subject that deserves a lot of attention. As with most
controversial topics, there are lots of opinions.

I’ll give you my opinion and then at the end of this post, I’ve
listed some soldering gas facts. I have some background with these
gases as I have worked as a professional engineer for a multinational
oil company for the last 24 years. Propane, natural gas and many of
the other soldering gases are products of the petroleum industry.

I have been making jewellery as a hobby for the last 10 yrs and have
soldered exclusively with 1 pound disposable propane tanks. I
currently have a little torch set up with oxy propane. I started out
with disposable oxy tanks, but found that they ran out way to fast,
so I switched over to a small (forgot the exact size) oxygen tank
which lasts forever for my needs. The reason that I use a one pound
propane tank (the kind the plumbers use) is that it is the smallest
size of propane tank that I can buy. The size of a propane fire or
explosion is reduced if the amount of propane (or any other gas)
available to burn is reduced.

I personally would not bring a 20 lb propane storage tank or an
acetylene B tank into my home. I believe that it exposes me and my
family to an unacceptable level of risk. A large leak ( it has to be
a large leak, tiny leaks of gas from threaded connections will
usually dissipate by themselves and are highly unlikely to explode)
of either one of these gases in a confined and unventilated space
such as a basement workshop can cause an explosion large enough to
seriously damage your house and injure its occupants.

I do believe that jewellers can safely handle these gases at home
and in their studios, but it is much easier to be safe if you are
well informed.

Below that I have cut an pasted a number of soldering gas facts from
a couple of posts that I sent into Orchid in 1997.

SOME FACTS TO HELP YOU MAKE YOUR OWN DECISIONS ABOUT SOLDERING
GASES; 1) Propane, acetylene, butane, natural gas will all explode
violently if mixed with air in the correct proportions and exposed to
a spark or flame and even a hot glowing piece of metal.

  1. Propane and butane are heavier than air and will sink or pool on
    the ground. Acetylene weighs about the same as air, and is referred
    to as neutrally buoyant, but still behaves a bit like propane and
    butane and usually wants to sink or just hang around. Natural gas and
    hydrogen are lighter than air and will rise.

  2. Whether a gas pools or rises makes little difference in a confined
    space such as a basement studio or a back bedroom. One of these gases
    leaking in a room with little or no ventilation is can form an
    explosive mixture with air. Once it finds an open flame it will
    explode.

  3. All propane tanks are equipped with a spring loaded pressure
    relief valve. This is required by law to prevent a propane tank from
    over pressuring and ripping open. When a propane tank is overfilled
    (especially in cold weather) and brought inside into a heated home,
    or left in the sunshine by a window, the liquid propane in the tank
    expands and vapourizes and pressure starts to build up in the tank.
    The relief valve pops open and lets some of the propane out of the
    tank to lower the pressure inside the tank. Once the pressure in the
    tank drops to a safe level, a spring on the valve pops it shut. This
    works just fine if the tank is located outside as the tank
    manufacturer intended, since the propane gas will disperse
    harmlessly, but not so OK inside your home.

  4. When transporting propane tanks in your car, ALWAYS transport them
    upright and leave your trunk slightly open. Transporting or storing a
    propane tank on its side could affect the ability of the relief valve
    to work, and if the hot sun warms up the propane in your trunk it can
    cause the propane tank to rip open. Also, it is a good idea to leave
    your trunk open a bit just in case the propane relieves out of an
    upright tank.

  5. Oxygen tanks have a device known as a rupture disk (also called
    burst disk or frangible disk). When an oxygen tank exceeds a certain
    safe pressure, the rupture disk ruptures and allows all of the oxygen
    to escape. It does not reclose and has to be replaced by a qualified
    person. An oxygen tank will generally only overpressure if it is
    exposed to extreme heat, such as a large fire. Leaving it out in the
    sun can NOT cause an overpressure as with propane.

  6. Acetylene tanks are equipped with a different device called a
    fusible plug. This is a plug that is set into a threaded hole in the
    tank. The plug is designed to melt when exposed to high heat from a
    fire. The plugs melt at somewhere between 205 to 240 F depending on
    the age and style of the tank. Once the plug melts it does not
    reseal, therefore the entire contents of the tank are emptied.
    Leaving an acetylene tank out in the sun, or in a hot room will NOT
    cause the fusible plug to open.

  7. You might wonder if its a good idea to empty an entire acetylene
    tank into a fire. The bottom line is that it is better to feed the
    fire than to have the tank explode and the pieces fly hundreds of
    feet.

  8. The reason that different tanks have different relief devices is
    a function of the properties of the gasses that are stored in these
    tanks. (by the way I am referring to B tanks, and other typical
    welding/soldering sized tanks) Propane is mostly liquid at its
    storage conditions, and vapourizes as it is drawn from its storage
    tank Oxygen is a gas at 2200 pounds storage pressure Acetylene is
    unstable and likes to explode under pressure, so it is actually
    dissolved in acetone at low pressures and comes out of the acetone
    solution as you use it.

If you plan to bring these gasses into your home or studio you should
consult the local fire department so that you know if it is legal and
also to get some professional advice on how to safely handle the gas.
You should also consult your insurer, to make sure that they will
cover you in the event of an incident.

Milt Fischbein
Calgary, Alberta, Canada


#2

Bravo Milt!! I think I have the same set up here in my shop in
St.Paul. Only I have the largest oxygen tank and two one pound
propane tanks connected together by a “T” fitting. Two pounds and
under is code in my area. You’d be surprised how long these tanks
last most times. With heavy casting weeks they still last about a
month. BE CODE COMPLIANT!!! Check out the rules in your area. Most
places allow one pound and under inside. Again check the Fire Codes.

Some additional comments about the set up. I use a gas ball valve
shut off for the top of the cylinder. This is done by having a camper
(RV) parts supplier connect a disposable tank top fitting to the ball
valve. This shut off now simply screws on the top of the disposable
tank. An easy combination that adds safety to your set up. A hose
fitting screws into the ball valve. I know Smith Torches sells a
fitting that screws to the top of a disposable propane tank, but it
shuts off simply by unscrewing. Not enough for me. I want to shut
this tank off at the end of the day.

The pressure regulator can also be a camper propane gauge. This is
preset for about five pounds of pressure. I’m not quite sure exactly.
It has always worked fine including casting platinum. So for bench
work, fabrication, gold & silver casting as well as platinum work and
casting it works great. With most any torch also. I connect a hose
from the ball valve to the gauge and the hose from the gauge goes to
the casting area as well as bench set up. You never have to touch the
regulator with it being preset. Not terribly expensive either.

Some have mentioned refilling these tanks. Don’t take this chance!
They are real cheap in the first place, about $3.00 per one pound
tank. I say this because when changing out an empty tank sometimes
the tank pressure sealed top, which keeps the gas in, will leak a
little bit and stay open. A little bit is like a flood to me. Pitch
the tank, don’t be cheap, buy a new one. I also try to buy the same
brand name of propane all the time. Coleman is the brand most
available here. Maybe someone could comment on weather there are
different grades of propane or not. Remember the manufacturer only
want to heat things up with these fuels, not have the purity grades
we would like.

Best Regards,
Todd Hawkinson


#3
Check out the rules in your area. Most places allow one pound and
under inside. 

Does that apply to only those tanks hooked up and currently being
used? How about an extra tank or two you keep at the ready?