When the system is exposed to supply, how often should water mist nozzles be replaced or a representative sample tested?

When the system is exposed to supply, how often should water mist nozzles be replaced or a representative sample tested?

• A. 5 years
• B. 20 years
• C. 10 years
• D. 15 years

Answer: (B)

Water mist nozzles that have been exposed to the system’s supply can undergo changes over time due to mineral buildup, corrosion, or elastomer wear. These changes can alter the orifice size and spray characteristics, which affects discharge density and pattern exactly when you need reliable performance in a fire event. Because of that, maintenance guidance uses a long-term testing/replacement cycle to catch these changes before they impact effectiveness without incurring excessive costs. Replacing the nozzles or testing a representative sample every twenty years provides a practical balance: it gives a high likelihood that any significant degradation is caught within a reasonable maintenance schedule, while not imposing overly frequent work on routine servicing. If a nozzle shows visible damage or testing reveals degraded performance, replacement should be done sooner rather than later.

Water mist nozzles that have been exposed to the system’s supply can undergo changes over time due to mineral buildup, corrosion, or elastomer wear. These changes can alter the orifice size and spray characteristics, which affects discharge density and pattern exactly when you need reliable performance in a fire event. Because of that, maintenance guidance uses a long-term testing/replacement cycle to catch these changes before they impact effectiveness without incurring excessive costs.

Replacing the nozzles or testing a representative sample every twenty years provides a practical balance: it gives a high likelihood that any significant degradation is caught within a reasonable maintenance schedule, while not imposing overly frequent work on routine servicing. If a nozzle shows visible damage or testing reveals degraded performance, replacement should be done sooner rather than later.