NFPA 13 Section 24 addresses testing before system acceptance. Hydrostatic testing pressurizes the system to 200 psi or 50 psi above maximum working pressure to verify no leakage. Water flow testing activates sprinkler heads to verify proper discharge patterns. System flushing removes debris and sediment from piping. Sprinkler head deflector alignment is verified with discharge patterns meeting design intent. Obstruction surveys check for new construction or building modifications blocking sprinkler spray patterns. Annual testing requirements include valve operation, flow testing, and visual inspection.