There seems to be much confusion on the list about natural gas
torches.
Residential natural gas is supplied to the house at a fixed pressure
typically no more than 11" WC (water column) this is about 1/2 psi.
With high pressure bottled gas (like propane) from a tank the way to
change the heat output of the torch is to change the pressure and if
necessary change the torch tip size. For natural gas appliances the
way to get more gas supplied is to use larger pipes. This is why
plumbers and the gas company will often suggest a 3/4 " line rather
than the standard 1/2" line. The low pressure of a house gas line
makes it hard to get very much natural gas through the torch because
the hoses and valves and tips for our torches are normally sized for
higher supply pressure of bottled gas. Plumbers and the gas company
may ask about the number of BTU’s required because there is a direct
relation between BTU’s and the size of the pipe and burner orifices
in a fixed pressure system.
So if you are going to use natural gas use as large a hose as you
can from the wall to the torch. Any torch that will work for propane
will work for natural gas with very little difference in
performance. The micro tip torches like the Little Torch from Smith
or the ones that use hypodermic needle tips will not work very well
if at all due to the small hose, valve and tip size if you are using
the natural gas straight out of the wall, but if you get a
compressor it will work just fine but compressors cost a fair bit of
money.
Hoke and Meco Midget torches work fine on bottled oxygen and natural
gas out of the wall just use 1/4" id hoses and the larger tips.
There are also specific natural gas torches but they are not as
popular with jewelers and can be hard to find but one brand to look
for is National (http://www.nationaltorch.com) they make both
gas/air and gas/oxy torches. These torches are designed for the low
supply pressure of natural gas and work great. The gas/air torch is
a little cool if you are used to working with oxy/gas but it is a
large soft flame and can help in reducing fire scale during
soldering. Gas/air is not very good for casting though due to its
lower flame temperature.
Jim Binnion
James Binnion Metal Arts
Phone (360) 756-6550
Toll Free (877) 408 7287
Fax (360) 756-2160
jbin@mokume-gane.com
Member of the Better Business Bureau