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Discharge of CF3I in a Cold Simulated Aircraft Engine Nacelle (NIST SP 984)



Jiann C. Yang, Samuel L. Manzello, Marc R. Nyden, M D. Connaghan


An aircraft engine nacelle refers to the region between the engine body and its casing. Fuel and hydraulic lines, pumps, and lubrication systems are located within the nacelle. Air is vented through the nacelle to prevent any build-up of combustible vapors, and underside drain holes are used to mitigate potential pooling of flammable fluids as a result of a leak. Once a fire is detected in the nacelle, the pilot will first level the aircraft before arming and discharging the fire suppressant. Depending on the configuration of the aircraft, the fire suppression bottle is mounted either adjacent to the engine nacelle or at a location several meters away from the nacelle, and the agent is transported through piping to the fire zone. Current aircraft fire suppression bottles for engine nacelle fire protection are normally filled with liquid CF3Br (halon 1301) to about half of the bottle volume, and the bottle is then pressurized with nitrogen to a specified equilibrium pressure (typically ~ 4.1 MPa) at room temperature. The purpose of using the pressurization gas is to expedite the discharge of the agent and to facilitate the dispersion of the agent. Without nitrogen pressurization, the bottle pressure, which is simply the vapor pressure of the agent, can be so low at cold ambience that there is not enough driving force to rapidly expel the agent from the bottle when needed.
Special Publication (NIST SP) - 984
Report Number


halons, halon alternatives, halon 1301, physical properties


Yang, J. , Manzello, S. , Nyden, M. and Connaghan, M. (2002), Discharge of CF3I in a Cold Simulated Aircraft Engine Nacelle (NIST SP 984), Special Publication (NIST SP), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed February 21, 2024)
Created June 1, 2002, Updated February 19, 2017