Back to Ganoksin | FAQ | Contact

Hot torch for propane

#1

Greetings, A while back an Orchid member wrote about the Precision LP
Gas Torch(German torch). Has anyone else in the US bought this and
had success?

I currently have a Smith Acetylene/Air torch with all the tips, but
I often struggle with it trying to get the metal up to temperature
fast enough. I read back through the archives, where this one is
often recommended, but I can’t seem to get the heat out of it. It’s
ok for little things. Maybe I am not using it correctly. Sometimes
when I first light it, the flame will shrink in size after a few
seconds.

I have propane/oxygen tanks and a welding torch with rosebud tip
that I use for melting. I would like a propane/oxygen torch that is
good for everything from the soldering the small stuff to melting. I
store my propane tank outside, so I think I have the safety issues
covered.

Thanks for any suggestions! Margaret

#2

Margaret, It sounds to me that you have not properly adjusted the
valve on the regulator that controls the flow of gas to the torch
head.

When you use a tip with a small oriface, the valve should be backed
partially out so the pressure does not blow the flame out. However,
when you change to a larger tip, you must turn the valve in almost to
the stop so you get the required pressure. The reason the flame
starts out strong and then shrinks is …there is pressure built up
in the hose when the torch is turned off but after opening the torch
and lighting it, the gas burns off and there is insufficient pressure
to keep it lit.

The Smith torch is engineered to give you a nearly perfect flame
just by using air instead of 02. In this case, as the pressurized
gas flows past the holes in the base of the tip, ambient air is
sucked in. As ambient air contains approx 20% 02 it mixes with the
proper amount of gas to burn at a hot even flame. If you turn down
the gas flow at the torch head, there is less gas but the lower
pressure will not pull in the right amount of ambient air. These
torches should always be used at full open (I don’t mean all 5 turns
of the knob…one full turn is the same as 5 in this case).

If you want more heat, use a larger tip, open the regulator valve by
screwing it in full, and open the knob on the head one full turn.

If that does not result in a full hot flame, have your local welding
supplier check the torch head…the filter system inside the body
of the torch may be blocked.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut2

#3

Hello Margaret, I’ve never used an acetylene/air torch. I use an
oxy/acetylene set up with the smith little torch. I haven’t run into
anything I can’t heat up adequately with this set up. Since you
already have the tanks and regulators, give the little torch a try
with the oxygen it will be a much hotter flame but very controlable.
Mark

#4

Are you working with gold or silver? If you are working with silver,
the torch you have is very good and what I use. The tip of the blue
cone is the hottest part of the flame and is what should be in
contact with your metal and in constant movement. Chain work is the
only thing for which the smallest tip is hot enough. If the flame is
getting smaller after you light it, I wonder if your gas tank is
almost empty. You may need to turn up the pressure a bit on the
regulator.

Marilyn Smith

#5

Margaret,

Be careful that you don’t crank up the pressure on your regulator to
the point you burst your hoses. The little torch only needs about
6-8psi pressure. Again, I don’t know what the air torch takes but I
don’t suggest cranking the pressure on the regulator all the way up.
A full acetylene tank can have 200psi in it. Probably more than your
line can safely take.

Adjust the pressure slowly and see if you can manage the flame
without too much of a surge. If the flame is difficult to manage you
might have a bad regulator or one that is too heavy duty for a light
torch. Sometimes the heavy bladders in a single stage regulator do
not handle low pressure well. You might need a different regulator on
the acetylene.

Usually the surge problems are on the oxygen side because those
tanks can hold up to about 2000psi. Two stage regulators work much
better on the oxygen side to get a smooth 6-8psi flow.

Mark

#6

Every torch tip has a range of heat output that it will provide.
For small work a small tip is fine as the size of the work increases
the size of the tip must increase. ( on low conductivity materials

  • i . e. stainless steel it is best to continue with the smallest
    tip that works since the heat is not pulled away as fast as it is
    with the high conductivity non ferrous metals. For brazing
    nonferrous metal work you always want a neutral or slightly
    reducing flame. A neutral flame has no"feather" at the end of
    the blue cone. This maybe hard to see and control so it is best to
    balance the flame with a slight colored “feather” at the end of the
    blue cone which is indication of a slight reducing flame.

If you try to increase the flame output from a given tip size by
increasing gas pressures you reach a maximum that works well.
Acetylene has a maximum safe working pressure of 15 psig and
appropriate regulators are redlined at this pressure. The gas in
the cylinder is at a higher pressure but it is dissolved in a
solvent( usually acetone) which makes it safe for storage.

A lot of silver jewelry work is done with the acetylene air
"Prest-o-lyte" type torch . With the right tip this provides enough
heat to get the entire piece up to soldering temperature. In Mexico
( and elsewhere) similar torches burning propane with air are used
very successfully - natural gas --air also can be used successfully
for brazing with tip sizes to match the work. MAPP gas burns a
little hotter but in not needed for small work.

The book “Silversmithing” by Finegold and Seitz is an excellent
source for on the subject of soldering and annealing
practices on the high conductivity non ferrous metals. It is
easy to find at Amazon and Borders books seem to always have a
copy.

Another excellent source for brazing that online is".

http://www.handyharmancanada.com/TheBrazingBook/bbook.htm

This is more industrial than jewelry oriented

Brazing is the more correct term for the jewelry "soldering
operation.

Fuel gas can be used with oxygen to get extra heat for melting
and for larger work brazing. In this case the extra heat applied
locally overcomes the high thermal conductivity and get the braze
-solder flowing.

jesse

#7 
    Be careful that you don't crank up the pressure on your
regulator to the point you burst your hoses.  The little torch only
needs about 6-8psi pressure. Again, I don't know what the air torch
takes but I don't suggest cranking the pressure on the regulator
all the way up. A full acetylene tank can have 200psi in it. 
Probably more than your line can safely take.

I believe Margaret mentioned that she was using a Smith ace/air
torch set up. If that is the case, unless the hoses are very old,
there is no problem using a full open single stage
regulator…especially if she is using larger tips. There are more
than one type of regulator…some with a secondary pressure gauge
showing pressure to the hose and those with no gauge. The latter is
made to be opened full. The former, with a gauge, redlines between 15
and 30 lbs but full open does not produce anywhere near 200
lbs…usually peaking at about 20 lbs max… Anything near that
will simply blow out the flame. My shop tank (with a torch similar
to the Smith) has a gauge and I keep it about 7 to 8 lbs. Our tanks
at the school, with no gauge, are routinely opened full when using
medium to large tips and we have never had any hose problems. Of
course, as I mentioned before, when using smaller tips, the regulator
valve needs to be backed out else the pressure blows out the flame.

Otherwise, as Mark says, the little torch set up only needs a few
lbs pressure.

Cheers from Don at The Charles Belle Studio in SOFL where it is
raining like crazy and where simple elegance IS fine jewelry!
@coralnut2

#8

Thank you all for your suggestions for using my Smith Acetylene/air
torch, I realize now that my struggles were self-inflicted. Don, your
explanation was especially useful, as I found it easier to understand
than the manual. Jake and Mark thanks also for additional
Wish I could join you all this year in Tucson. I have
benefited so much from Orchid! Thanks to all! Best Wishes, Margaret

#9

Hi Margaret,

I have an oxygen/propane set up. After the regulators, I have "Y"
connectors with hoses going to two separate torches. Each branch of
the “Y” has its own valve so I only turn the gas on to the torch I
am using. One branch goes to a Meco Midget torch which I use for
soldering and small work. The other branch goes to a Meco Aviator
Jet (model 63131) with a No. 2H tip which I use for melting and
larger work. One set of tanks and regulators, two torches.

Dale