System Sensor WFD40 Water Flow Switch Detector

The System Sensor WFD40 Water Flow Switch Detector is a vane-type sensor used in fire sprinkler monitoring to detect water movement in wet-pipe sprinkler networks. It is designed for 4-inch steel pipe and provides a 4 to 10 GPM activation range with a 450 PSI static pressure rating, and it uses dual SPDT switches rated at 10 A, 1/2 HP at 125/250 VAC. This pipe-mounted device can be installed in either a horizontal or vertical orientation and features a NEMA 4 enclosure for durability in challenging environments; it transmits alarm signals to fire alarm control panels, making it a common choice in commercial buildings, industrial facilities, and warehouses where reliable water flow monitoring and alarm activation are required. Common replacements include System Sensor WFD40A, Potter VSR-F, and Reliable VSR-4.