Craig Martell on tue 22 sep 98
Hi:
Propane is about 2.5 times hotter than Natural Gas, so the first thing you =
have
to deal with is enlarging the burner orifices so you will get the same BTU
output, when switching to Nat Gas. You don't want to change the operating
pressure of the burners because they are designed to be efficient at the
pressure you are using. Well, hopefully that is true.
One big advantage with Nat Gas is not having to get the tank filled on a =
regular
basis and having to worry about freeze ups when the weather gets chilly. If=
you
live in a warm climate, this is a moot point. Nat Gas isn't heavier than =
air
like LPG so you don't have to be paranoid about gas pockets collecting in
depressions, if you develop a line leak.
A Nat Gas flame is quite different from propane. If I remember correctly, =
Nat
Gas is pure CH4-Methane. More opaque, with more of an orange color, and is =
much
easier to see than a propane flame. If you have some way of analyzing the =
kiln
atmosphere, the change should not be too traumatic in terms of getting a =
similar
result. When I changed from Nat Gas to Propane, my pots weren't as rich for=
a
bit when I was getting my bearings with Propane. I live in a rural area and
there isn't any Nat Gas line here. If there was, my choice would be Natural
Gas.
happy cooking, Craig Martell-Oregon
Michael McDowell on wed 16 dec 98
Chess,
I think the relative hazards of propane vs. natural gas have been pretty well
covered by now. If your house is already set up for Natural gas, and it's just
a matter of extending it to the backyard where the kiln is, it may well be the
best way to go. But you say the expense and bother of doing so is also of
concern to you. On those grounds, the decision might end up hinging on whether
you rent or own your place. Certainly if you are renting, or are considering
moving in the next couple of years or so, extending natural gas to the kiln
sounds less like a good idea. Propane is a good fuel, and it will be safe if
you are safety conscious. Some of your concerns with regard to it's efficiency
have not been as thoroughly addressed as the safety issues.
The sluggishness and flame out the stack you describe may be indications of
either too large an orifice size and/or insufficient primary air for the
amount of fuel entering the kiln. Another problem with propane is this icing
up of tanks and lines as fuel vapors are taken off the liquid propane in the
tank. I'm surprised I've not heard mention of Nils Lou's beautiful liquid
propane burners. Especially for a kiln firing from smaller propane bottles
that you haul out to fill, these burners would seem just the ticket for you.
Since they draw liquid propane from the tank and vaporize it right at the
burner, there is no problem with icing up the tank and lines. It's been a long
time since I fired with propane, but if I ever do again, I'll get more info on
those burners.
Michael McDowell
Whatcom County, WA USA
mmpots@memes.com
http://www2.memes.com/mmpots
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