System Sensor WFD40 | Waterflow Detector for 4″ Steel Sprinkler Pipe | NEMA 4 Rated – UL/FM Approved

The System Sensor WFD40 Waterflow Detector is a high-performance vane-type waterflow detector designed to monitor water movement in 4-inch wet pipe fire sprinkler systems. Engineered for dependable fire alarm activation, the WFD40 features a rugged NEMA 4-rated enclosure, dual synchronized SPDT (Form C) contacts, and an adjustable pneumatic retard mechanism that minimizes nuisance alarms caused by pressure surges or trapped air within the sprinkler piping.

Designed for both indoor and outdoor installations, the WFD40 mounts directly to 4-inch Schedule 7 through Schedule 40 steel sprinkler pipe and is ideal for commercial, industrial, institutional, and residential fire sprinkler systems installed in accordance with NFPA 13, NFPA 13D, NFPA 13R, and NFPA 72.

The corrosion-resistant enclosure features wire-ready terminals, visual and audible switch activation, and a field-replaceable timer and switch assembly for simplified installation and maintenance. Whether used in new construction, system upgrades, or replacement applications, the WFD40 delivers dependable waterflow detection while meeting the demanding requirements of modern fire protection systems.

Technical Specifications

• Manufacturer: System Sensor
• Model: WFD40
• Product Type: Waterflow Detector
• Detection Method: Mechanical Vane-Type
• Compatible Pipe Size: 4″
• Compatible Pipe Schedule: Schedule 7–40 Steel Pipe
• Required Hole Size: 2″
• Static Pressure Rating: 450 PSI
• Flow Threshold: 4–10 GPM
• Maximum Water Surge: 18 Feet Per Second
• Operating Temperature: 32°F to 150°F (0°C to 66°C)
• Enclosure Rating: NEMA 4
• Contacts: Two SPDT (Form C)
• Electrical Rating: 10A @ 125/250 VAC, 2.5A @ 6/12/24 VDC
• Conduit Entrances: Two ½” conduit openings
• Compatible Systems: Wet Pipe Fire Sprinkler Systems
• Service Standards: NFPA 13, NFPA 13D, NFPA 13R & NFPA 72
• Approvals: UL Listed, ULC Listed, FM Approved
• Warranty: 3 Years

Key Features

• Designed for 4″ steel wet pipe fire sprinkler systems
• Vane-type waterflow detector
• Rugged NEMA 4-rated enclosure
• Suitable for indoor and outdoor installations
• Adjustable pneumatic mechanical retard mechanism
• Reduces nuisance alarms caused by pressure surges
• Visual switch activation indicator
• Audible switch activation (73 dBA)
• Dual synchronized SPDT (Form C) contacts
• Wire-ready terminal block for simplified installation
• Field-replaceable timer and switch assembly
• Corrosion-resistant lightweight housing
• Tamper-resistant cover screws
• Two ½” conduit entrances
• Compatible with Schedule 7–40 steel pipe
• UL Listed
• ULC Listed
• FM Approved
• 3-Year Manufacturer Warranty

Applications

• Wet Pipe Fire Sprinkler Systems
• Commercial Buildings
• Industrial Facilities
• Manufacturing Plants
• Warehouses
• Distribution Centres
• Office Buildings
• Hotels
• Schools
• Hospitals
• Apartment Buildings
• Condominiums
• Institutional Facilities