TECHNICAL NOTES Combustible Dust Flame Propagation and Quenching in Pipes and Ducts FINAL REPORT BY: Alexander Ing National Fire Protection Association, 1 Batterymarch Park, Quincy, Massachusetts, USA. December 2018 © 2018 Fire Protection Research Foundation 1 Batterymarch Park, Quincy, MA 02169-7417, USA Email:
[email protected] | Web: nfpa.org/foundation ---page intentionally left blank--- —— Page ii —— FOREWORD A technical basis is required for determining when pipes or ducts are too small in diameter to permit the propagation of combustible dust deflagrations. This must be evaluated considering the characteristics of the equipment system (pipe/duct diameter and length), properties of the combustible dust, and operating conditions (pressure, temperature, flow rate, etc.). The knowledge will permit establishing rational protection requirements in NFPA’s various combustible dust fire and explosion prevention standards. There is also a lack of knowledge around conditions influencing the explosion propagation through piping, especially small diameter piping. Having a clear understanding of experimental testing data would allow analysis to see what conditions and parameters will affect the explosion propagation and also point out where there are knowledge gaps. This comprehensive literature review project seeks to identify the parameters affecting flame propagation involving combustible dusts within pipes and ducts, and seeks to determine the conditions under which a combustible dust flame will not propagate (i.e., will quench) within a piping or ductwork system. The following tasks have been carried out for this project: 1) Identify the conditions under which combustible dust deflagration will not propagate within a piping or duct work system. 2) Identify the factors (pipe diameter, pipe length, dust type, and dust concentration) affecting the explosion propagation through pipes from relevant literatures.