What is an Explosion?

We are going to focus our discussion on “Explosions”, its definitions from a scientific, regulatory, and societal perspective. We will point out that as defined these definitions are not consistent and lead to ambiguity. Of particular interest to this work is how this current ambiguity affects the emerging Regulation Codes and Standards (RCS) as applied to hydrogen technologies. While this manuscript has its roots in combustion science with extension to both the standard development and regulatory communities for hazards at large, the unique behavior of hydrogen in many configurations motivates examining the relevant definitions and language used in these communities. We will point out the ambiguities, how this leads to confusion in supporting definitions, and how it leads to overly restrictive RCS for hydrogen applications. We will then suggest terminology which is not ambiguous, internally self-consistent, and allows appropriate RCS to be promulgated to ensure the safety of the public and capital, to ensure the correct response of first responders, and allow cost effective development of hydrogen technologies in our infrastructure.