Paul Lewing on fri 3 nov 00
Remember that the safety precautions for gas kilns and for propane kiln
are exactly opposite of each other. Natural gas is lighter than air,
propane is heavier than air. So if a natural gas kiln is left unlighted
for very long, you should leave a vent hole of some kind near the top of
the arch to prevent gas buildup. In a propane kiln, leaking propane
will collect at the bottom of the kiln. It's important to leave an
outlet at the lowest point of the kiln for the propane to flow out of,
and for there to be ventilation along the floor.
Paul Lewing, Seattle
mel jacobson on fri 3 nov 00
having just read john baymore's post on kiln problems,
it reminds me of how important it is to have a warm stack
when starting a kiln.
i use a small burnz o matic torch, light it, place the flame in
the damper port and let some warm air into the stack.
this takes about 3 minutes.
i still pre-heat my kiln with a small burner over night.
if the flue is not open a crack unburned gas will build in
the kiln. when the kiln is lit, well, you can have a back
flash.
if you use the torch on the stack it will pull that gas out
as the stack is warmed. this makes the lighting much safer.
i like things going up the stack, not down.
just heard of a big flooosh back flash at an art center...of
course the baso valve had a c clamp on it. nice. that is one
of the dumbest tricks a potter can pull. and then teach that
to a student that is firing a kiln for the first time.
jeeez. they have to re'set the arch.
taking a few extra minutes before lighting a gas kiln can be
one of the best things you can do.
it is like the pilot walking around the plane before takeoff.
it puts the responsibility for that craft in the hands of the
captain. do that with your kiln each time you fire. and talk
to yourself out loud. `gas valve on, stack warm, all burnables
out of the way, ready to lite`.
mel
FROM MINNETONKA, MINNESOTA, USA
http://www.pclink.com/melpots (website)
ferenc jakab on sat 4 nov 00
>
> I use a small burnz o matic torch, light it, place the flame in
> the damper port and let some warm air into the stack.
> this takes about 3 minutes.
>
Mel,
My burners have pilots and I always steam/smoke the kiln for at least 12 hrs
usually longer as I often put "last minute" green ware in the kiln. My
baffle/damper (O.K. Vince?) is always open at least 1/4 way. This way the
chimney is always drawing by the time I light the first burner at about
100deg C. I'm wondering why pilot burners are not more popular? They are
extremely useful and a great safety feature, especially when coupled with a
safety cut out.
Feri.
P.S. I NEVER EVER light up with the door closed. Even on the big kiln where
I have to build the door in I light the first pilot before building the door
in. I have baffle plates under each burner which are closed when I shut down
and I do not pull these out until each subsequent pilot is lit.
John Weber on sun 5 nov 00
Maybe I'm confused about how you are warming your kiln, but it seems to me
that the process of warming a kiln with the flu only open a crack is a very
dangerous practice. When I warm my kiln overnight I always set it so the the
stack damper is completely open. Can you clarify this for me?
ferenc jakab on mon 6 nov 00
Maybe I'm confused about how you are warming your kiln, but it seems to me
> that the process of warming a kiln with the flu only open a crack is a
very
> dangerous practice. When I warm my kiln overnight I always set it so the
the
> stack damper is completely open. Can you clarify this for me?
>
John,
I presume your question is directed to me? I have the damper 1/4 open. The
flue on my small kiln measures 7" x 9", 1/4 of that is almost 16 sq" of vent
space for two 1/2" pilot burners. These are coupled to safety cut-outs with
9 second thermocouples. My burner system is full pressure, meaning 130 psi
and I adjust the pilot pressure to 2 - 4 psi. With the damper full open I
would have a vent size of 63 sq ". I would have to use a lot more gas to
achieve the same result. Hope this satisfies your curiosity?
Feri
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