After hold time, what occurs in NFPA 2001 discharge process?

• A. The space is vented to outside
• B. The system is cleared and normal conditions resume
• C. The agent concentration is increased further
• D. The detectors are recalibrated

Answer: (B)

The hold time is the designated period after discharge has begun during which the space is allowed to achieve and act on the extinguishing effect. When that hold time expires, the discharge sequence is considered complete and the system is cleared, allowing normal conditions to resume. In practice, this means the space is verified safe for re-entry and any remaining agent is managed through purge/dilution as needed so concentrations return to acceptable levels, and the system returns to its standby state.

Venting to the outside, increasing the agent concentration further, or recalibrating detectors are not part of the hold-time step. The hold-time step ends with the space transitioning back to normal conditions.