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Natural Gas - Actual Numbers


#1

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.
If they can’t tell correct you about the torches they
sell without having more Tech support should be given
guidelines as to what questions to ask and where to go to get the
answers. Too much ignorance about the issues from even the Sales
people (so called tech support) at the OEM.

I think 3/4 " pipe equipped with a back flow prevention device in
the piping or on the torch will work for most anything except high
heat requirements like casting. The oxygen will be adjusted at it’s
regulator. No adjustment for the Natural Gas except the hand valve.
And bigger tips (orifices) used than for LP or Acetylene. Cooler
flame, less heat, slower heating time etc.

To amplify: The regulator at the house meter supplies no more than
1/2 psi. More can damage the gas valves used on furnaces, water
heaters etc. (It’s printed right on the side of the valves. approx 14
in w.c. to 1/2 psi) When all appliances are shut off the pressure
rises to a “lock up” pressure from the meter regulator so setting at
11 in wc keeps it below 1/2 psi. The gas valves at the furnace etc.
drop the pressure to approx 3.5 inches of water column to feed the
burner orifices. Natural Gas has less heat content per cubic foot than
LP (propane) the standard is 1 therm; 1000 BTU’s per Cubic Foot for
Natural Gas. If I convert a furnace from Natural gas to LP the
regulator in the gas valve at the furnace is removed and the
regulation is provided by the LP regulator at the house. The standard
is 10.5 to 11 in wc pressure for LP. The orifices are changed to ones
with a much smaller hole. Altitude enters into the picture somewhere
also.

Given:
altitude 0-2000 feet
standard heat content of gas (LP or Natural)
pressure at orifice
size of orifice
the heat output should be able to be figured

Anyone can measure inches of water column by using a glass and
hooking a tube to the gas. The tube is inserted into the glass with
the other end connected to the gas source. As the tube is raised or
lowered into the glass bubbles form from the end. At the point that
the bubble forms but doesn’t push out you measure the depth of
insertion into the water. That is Inches of Water column!

All of the talk about pounds of pressure for a natural gas is for
large systems like glass kilns, factories, or long piping systems. My
suggestion is to see if the torch tech support can or will, supply
heat output ranges (BTU’s) for given size tips. Then a regulator
supplier of natural gas regulators should be able to tell you if it
is possible with standard available gas pressures and what size line
is needed.

Dan Wellman


#2

Hello Orchidland,

I’ve been using NG for… hmmm, at least 15 years with no problems. A
simple set-up with one torch. No pressure regulator or booster
needed, and the connection is through a hand valve to the NG line
that feeds the water heater and furnace.

With standard safety precautions (close the hand valve when done for
the session), NG is the 3Cs: clean, convenient, and cheap. Be
confident; talk to your local welding supplier (who will be your
source of compressed oxygen); it’s not rocket surgery. Judy in
Kansas

Judy M. Willingham, R.S.
B.A.E. 237 Seaton Hall
Kansas State University
Manhatttan KS 66506
(785) 532-2936 FAX (785) 532-6944