In the U.S., the main body developing the design standards of kilns, furnaces and ovens is the National Fire Protection Association (NFPA), through NFPA 86 Standard for Ovens and Furnaces. But the ceramic industry has misconceptions about NFPA 86, and no wonder.
Carbon is one of the earliest known elements. It was used by the Egyptians and Sumerians in the form of charcoal around 3750 B.C. for the reduction of copper, zinc, and tin ores in the manufacture of bronze.
As discussed in Part 1 (CI, September 2011), internal kiln pressure in a tunnel kiln governs airflow direction and affects temperature uniformity, soaking time, and energy consumption. Management of the kiln pressure profile makes a huge difference in kiln stability.