Inside the main case of the Model 111, the compressed air is further reduced to the final
desired pressure (10 to 30 psi). The air then passes into a column of Purafil (potassium
permanganate on alumina), which oxidizes NO to NO2. The air then passes through a
column of iodated charcoal, which removes NO2, and S02. Finally, the air goes into the
reactor where it is heated to 350 oC over a catalytic surface, which oxidizes CO to CO2,
and hydrocarbons including methane, to CO2 and water. Figure 4-2 shows the layout of
these components.