Water wash shall be inoperable for a minimum of how many seconds upon operation of the automatic sprinkler?

• A. 30 seconds
• B. 60 seconds
• C. 90 seconds
• D. 120 seconds

Answer: (B)

The key idea is the time delay in the water wash release after the automatic sprinkler starts. The water wash must be held out of operation for a short, defined period so the sprinkler system can initiate its extinguishing action first, allowing the agent to begin cooling and suppressing the fire without being immediately diluted by the wash. Sixty seconds provides a balance: long enough for the initial suppression sequence to take effect, but short enough to prevent excessive delay in washing out residues if needed. A shorter delay could cause premature flushing and potential dilution of the extinguishing effect, while a longer delay could allow more fire development before washing.