An NFPA 13 fire sprinkler system requires listing of a main control valve and

In an NFPA 13 fire sprinkler system, a main control valve must be listed, and a flow switch is also required to monitor water movement in the system, signaling activation of the sprinklers. The flow switch is a critical component for system monitoring and alerting.

References: NFPA 13 requirements for the installation and components of fire sprinkler systems, emphasizing the importance of listed equipment and system monitoring devices.