Federal Aviation Regulation (FAR) 25.855 requires certification tests of fire suppression systems to be installed onboard Class C aircraft cargo compartments. This regulation is to certify the operation of the system and to ensure adequate concentration of the extinguishing agent in the compartment during the certification tests. On March 1998, the FAR was modified to include the conversion of Class D cargo compartments into Class C versions. It is expected that the aviation industry will be discharging quantities of Bromotrifluoromethane (Halon 1301) into the atmosphere to comply with the certification tests of the converted cargo compartments since halon is the preferred agent. In favor of reducing the atmospheric ozone depletion caused by the use of halons, the International Halon Replacement Working Group formed a task group to identify an agent that could simulate halon during these and future certification tests.

This paper describes the testing and results of the evaluation of pentafluoroethane (HFC 125) and sulfur hexafluoride (SF₆) as Halon 1301 simulants for cargo compartment certification testing. Results indicate that based on similarities in concentration profiles, decay rates, and metering system agent concentration, SF₆ is the better of the two agents evaluated to mimic halon as a fire suppressant simulant in an aircraft cargo compartment.