What Does Deflagration Potential Mean?
Deflagration potential describes the potential of a given material or substance to deflagrate.
The term “deflagration” refers to any form of combustion (e.g. fire, explosion) that spreads at subsonic speeds. If combustion occurs faster than the speed of sound, it is referred to as detonation.
Safeopedia Explains Deflagration Potential
Many occupational health and safety standards are concerned with the deflagration potential of a specific material or environment. It is a particular concern in workplaces that contain large amounts of combustible dust. Safety requirements related to combustible dust are designed to ensure that dust concentration within the workplace remains below the point of deflagration potential.
When it is not possible to keep a substance at a concentration below its deflagration potential, employers must take additional safety precautions (i.e. implement hazard controls) to limit the probability of—and potential damage from—a deflagration occurring.
Deflagration potential is a prominent concern within the International Building Code (IBC), a system of safety codes that have been adopted as legal regulations within all 50 U.S. states. The IBC describes buildings with a deflagration potential as “H-2” buildings, a category that denotes the second-highest hazard level for buildings. The highest level, H-1, refers to buildings containing materials with a detonation potential.
The National Fire Protection Association (NFPA) considers deflagration potential within the context of NFPA standards concerning combustible dust. An example is NFPA 68: Standard on Explosion Protection by Deflagration Venting, which applies to contexts where an environment has a specific deflagration potential.
A material can be considered to have deflagration potential if its experimental enthalpy through decomposition is greater than 250 cal/g in an environment that does not contain oxygen. The meaning of enthalpy in this context is roughly equivalent to "heat-generated."
When employers are evaluating the deflagration potential of a specific workplace context, they must account for both primary and secondary deflagration potentials. Primary deflagration potential refers to a substance that has an immediate potential to deflagrate given exposure to an ignition source. Secondary deflagration potential refers to a substance that does not necessarily have immediate potential to deflagrate but that could do so if exposed to a primary deflagration or a detonation.