LindaBlossom on thu 31 jul 03
Thank you all for the answers regarding the oxyprobe. I was surprised to
learn that the oxyprobe is not forever. Nowhere in the instructions that I
received with it did it mention anything about this. I would have liked to
have known before using it in EVERY firing. (over 100) I have checked and
restripped all the ends on the three wires and the temperature reading is
still very far off. I bought a digital pyrometer from a guy on ebay - it is
great. It was $65 plus shipping and he is great to deal with.
I fired the gas kiln for the second time. It had gone into reduction on the
first firing and I was unable to advance because I couldn't raise the
burners without reducing. I had the orifices braised closed and I
redrilled them much smaller. The same problem happened on the next firing.
I also had very strong back pressure at the top two holes, neutral at the
middle, and negative pressure at the bottom one. So negative that the cones
tried to bend sideways!! The burners come in the back, the kiln is almost a
36" cube, and the flue in in the bottom of the back wall. Any ideas where
to begin dealing with this pressure problem?
Now for the really interesting thing. I fired to cone six. One piece I
unloaded was at the back near one of the burners. It looked really good -
but it had an area at the bottom about 1 1/2" high and four inches wide that
was white - chalky white. It was unfired glaze. I was able to scrape it
off! Any thoughts, Anyone?? How can a glaze remained unfired to such a
degree in a box that is that hot???
I am taking the orifices to be rebraised and I will drill them even smaller.
Really small and work my way up this time. They were drilled at wire guage
40 - I haven't decided where to try next as it is almost guesswork. The
Olsen book had a size of 29 for the kiln size and number of burners (2) and
they were smaller than that when I started. These are used burners so I
don't know a lot about them but I did talked with the previous owner and he
used two of them for a kiln about the size of mine.
Any suggestions would be helpful. My previous kiln had four burners on the
sides and it never gave me a day of grief so having a kiln that is behaving
so weird is quite an experience. Like having another teenager.
Linda
Ithaca, NY
Mondloch on fri 1 aug 03
Hi Linda,
I also have about 100 firings on my oxyprobe in a typical 60 cu MFT car kiln
with two burners coming in from the back.
Although the atmosphere readings have always seemed accurate and sensitive,
the temperature readings have been erratic right from the start. I sent it
back once but it came back the same.
The erratic oxyprobe temp readings were confusing the heck out of me so I
bought a Fluke double probe digital pyrometer... stuck one probe bottom back
and one top front. I love it. It's sensitive so I can tell immediately if
damper/burner adjustments are increasing heat gain and also, importantly I
think, where the heat is going in the kiln from those adjustments. It also
makes monitoring cool-down easy.
If the temp reading on the oxyprobe seems off by what the pyrometer is
telling me, I can get it to give me what I know it 'should' be telling me by
turning it off for a bit or wiggling on the center black terminal. I have no
clue why- perhaps someone who understands oxyprobes can explain that. I only
use the temp readings on the oxyprobe to graph my firings on the graph they
send when you buy the probe, but I do like using that graph. It tells at a
glance how the firing compares to previous ones.
All in all, I find the probe very useful for the atmosphere readings when
used along with the pyrometer. These two tools were/are my teacher to learn
how to fire with gas.
I have no idea if any of this will be helpful to you, but I thought I'd put
it out there in case you can glean something from it.
Sylvia
---
Mark & Sylvia Mondloch
Silver Creek Pottery & Forge
W6725 Hwy 144
Random Lake ,Wi 53075
HotArt@silvercreekpottery.com
http://www.silvercreekpottery.com
Jennifer F Boyer on sat 2 aug 03
For what it's worth, I've been using an Oxyprobe for over 18 yrs
in two different propane kilns(had to repair/replace parts over
time) and the temp rise has always been rock solid. I've had the
probe part in the middle the door, off to the side of the door
and through the roof(bad placement-heat rise burned out the
probe base) in kilns with 2 different burner set ups. I just
didn't want people to think they never work as advertised! Nils
Lou has always been great about fixing it when things go wrong.
I also have a Fluke double and love the 2 together. I'm amazed
at how a tiny movement(1/2") of the damper is the difference
between oxidation/reduction or stall/temp rise. My kiln tends to
fire cool on the bottom so the Fluke really helps with getting
the bottom to catch up....
Jennifer
Hang in there Arti- your big ole heavya** pot is in a place of
honor at my house
Mondloch wrote:
> Hi Linda,
>
> I also have about 100 firings on my oxyprobe in a typical 60 cu MFT car kiln
> with two burners coming in from the back.
>
> Although the atmosphere readings have always seemed accurate and sensitive,
> the temperature readings have been erratic right from the start. I sent it
> back once but it came back the same.
>
> The erratic oxyprobe temp readings were confusing the heck out of me so I
> bought a Fluke double probe digital pyrometer... stuck one probe bottom back
> and one top front. I love it.
--
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jennifer Boyer
Thistle Hill Pottery Montpelier VT USA
http://www.thistlehillpottery.com/
Never pass on an email warning without checking out these sites
for web hoaxes and junk:
http://urbanlegends.about.com/
http://snopes.com
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
| |
|
