For Halocarbon clean agents, what is the maximum discharge time to achieve 95 percent of the minimum design concentration for flame extinguishment, based on a 20 percent safety factor?

• A. 30 seconds
• B. 60 seconds
• C. 10 seconds
• D. 120 seconds

Answer: (C)

The amount of time allowed for the agent to discharge is tied to reaching a target concentration quickly enough to extinguish the fire, while accounting for variability with a safety margin. For halocarbon clean agents, the rule is to ensure the space reaches 95% of the minimum design concentration (MDC) for extinguishment, using a 20% safety factor. These agents are highly effective and distribute rapidly, so the concentration can reach that near-target level in a very short burst. Therefore, the maximum discharge time is around ten seconds, which best guarantees that 95% of the MDC is achieved during the discharge period. The longer times would not meet the same 95% target within the discharge window, given typical room volumes and delivery characteristics.