Journal Lists User Guide InfoTrac Demo Student Resources Instructor Resources User Comments InfoWrite
Research and the Research Paper Grammar The Writing Process Special Kinds of Writing Modes of Exposition Critical Thinking
Home > InfoWrite > Modes of Exposition > Division and Classification
To understand how a filter regenerates, one must understand how soot or PM burns. Traditionally, combustion of soot is done in an oxygen atmosphere (air). In air, soot will burn at about 450° to 500° Centigrade (840° to 930° F). However, this is not a typical operating temperature for diesel engine exhaust. As a result, in order to burn soot in air, an active system, one that increase the temperature of the exhaust using some external heat source, is required. But if an active system is not carefully controlled, it can often experience an "uncontrolled burn" where the temperature increases to 600° C (1112° F) or more. This will damage the filter element and also pose some potential risk to the vehicle.