What type of piping supplying fire pumps must be flushed according to NFPA 20 requirements?

The correct choice, pertaining to the type of piping supplying fire pumps that must be flushed according to NFPA 20 requirements, is suction piping. NFPA 20 emphasizes the necessity of ensuring that all water supply lines connected to fire pumps are free of debris, contaminants, and potentially harmful materials that could impair the function of the pumps.

Flushing the suction piping is vital because this section of the system directly draws water into the pump. Any sediment or obstruction in this piping can reduce the efficiency and reliability of the pump, which is critical for fire protection systems where immediate availability of water is essential. The flushing process helps to maintain the integrity and performance of the fire protection system by promoting a clean water supply to the pump.

While other options involve various parts of the fire protection system, they do not specifically have the same flushing requirement outlined for suction piping under NFPA 20, which focuses on the importance of ensuring a clear pathway for water entry into the fire pump.