Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Fluid Dynamics of Agent Discharge (NIST SP 861)



William M. Pitts, Jiann C. Yang, G. Gmurczyk, Leonard Y. Cooper, William L. Grosshandler, W G. Cleveland, Cary Presser


The extinguishment of a fire using gaseous agents is a very complicated process which is not completely understood. Current fire-fighting agents such as halon 1301 and halon 1211 are believed to function by a combination of chemical (catalytic removal of hydrogen atoms at the flame front due to the presence of bromine atoms) and physical (cooling and dilution of flame gases) actions. All of the proposed alternative agents are known to be less effective (i.e., considerably higher molar concentrations of the agent are required) than halon 1301. This reduction in effectiveness is attributed to the absence of bromine atoms in these chemicals and thus the absence of a highly effective chemical means of fire extinguishment.
Special Publication (NIST SP) - 861
Report Number


halons, fluid dynamics, discharge rate, dispersions, equations, sprays


Pitts, W. , Yang, J. , Gmurczyk, G. , Cooper, L. , Grosshandler, W. , Cleveland, W. and Presser, C. (1994), Fluid Dynamics of Agent Discharge (NIST SP 861), Special Publication (NIST SP), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed July 16, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created April 1, 1994, Updated November 10, 2018