Many NFPA codes and standards, in particular NFPA 400, Hazardous Materials Code, specify separation/clearance distances for hazardous chemical storage and processes from other equipment and occupied buildings. Many of these requirements have historical undocumented origins. Guidance, which may inform a sound technical basis for adjusting these distances, has been requested by NFPA Technical Committees. There are a number of methodologies in the literature, both risk and hazard based, which are used in the chemical safety process safety field that may be relevant to the calculation of these distances.
The purpose of this project is to provide guidance to NFPA technical committees on methodologies to develop technically based separation/clearance distances for hazardous chemical storage/processes and their application to the chemical storage and processes. The specific focus of the project is those hazards within the scope of NFPA 400. The literature review of separation distances is included in the report along with a verification case study using Ammonium Nitrate solids.