Ivor and Olive Lewis on sun 5 aug 07
Dear Bob Johnson,=20
You give this in quotation
<flame is created, increasing the amount of carbon monoxide that is a by =
product of efficient combustion, creating an even and effective reducing =
atmosphere throughout the kiln, >>
I believe it is not made clear that "Efficiency" in this context refers =
to mixing of the gasses, not to extracting the maximum BThU's from a =
given volume of fuel and air. In the latter case, the balance between =
fuel and Oxygen will achieve the maximum energy release if there is no =
Carbon Monoxide and the products of combustion, Carbon dioxide, Water =
and Nitrogen if using gas.
I would suggest that control of Secondary Air determines the reactive =
nature of gas that has been mixed efficiently. Decreasing the flow of =
secondary air will encourage the production of Carbon Monoxide from that =
"Bushy Flame"
What may not be appreciated is that those oxides which can be reduced to =
a lower oxidation state or to their metallic state to produce colour do =
so at differing partial pressures of Oxygen. In using an instrument that =
senses Oxygen in a kiln atmosphere, the raw reading may guide but =
conversion of the voltage to Oxygen Partial Pressure would be more =
informative when used with information from "Introduction to Ceramics" =
by David Kingery and others.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
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