Which portions are exempt from flushing during service?

• A. Those portions of the system normally containing foam concentrate when the system is in service
• B. The suction lines
• C. The sprinkler heads
• D. The drain valves

Answer: (A)

In a foam-water sprinkler system, flushing during service is intended to clear debris from the parts that carry water, while keeping the foam concentrate portion intact. The portions that are normally filled with foam concentrate when the system is in service are exempt because they are designed to remain charged with concentrate. Flushing these sections could remove or dilute the concentrate, disrupting the foam solution and the system’s intended operation. They’re typically isolated from the water-only flushing loop, so they’re not part of the normal flushing procedure.

The other components listed—suction lines, sprinkler heads, and drain valves—are not exempt because they are part of the water circulation and drain paths that need flushing or draining to ensure the system is clean and free of debris before returning to service.