Pyrolysis

Definition

Pyrolysis refers to the breakdown (lysis) of condensed-phase materials by heat (pyro), generating gases and vapors in the process. The significance of pyrolysis to fire is that most of the gases that burn in flames, whether from burning vegetation or materials from the built environment, are formed via pyrolysis. In combustion chemistry and related fields, pyrolysis also refers to thermal breakdown of gaseous molecules.

Introduction

As it is currently used by the fire community, pyrolysis refers generically to the liberation of gaseous volatiles from a solid fuel, regardless of the presence or absence of oxygen. However, in other fields of engineering, pyrolysis generally refers to thermal decomposition of solids in the absence of oxygen. For clarity, when thermal breakdown of materials occurs in the presence of oxygen, it is sometimes referred to as oxidative pyrolysis.

During pyrolysis, a mixture of gases and vapors (collectively referred to as pyrolysate) is formed from...