System Sensor WFD40N 4″ Fire Sprinkler Water Flow Switch – UL/FM, NEMA 4, 450 PSI

WFD40N 4″ Fire Sprinkler Water Flow Switch – UL/FM Listed

The System Sensor WFD40N is a 4 inch vane-type water flow switch designed to monitor flow in wet-pipe fire sprinkler systems. Engineered for dependable performance in demanding conditions, this switch is UL Listed, FM Approved, and housed in a NEMA 4 weatherproof enclosure for indoor or outdoor installations.

Top Features:

• Fits 4″ Schedule 7–40 steel pipe
• UL Listed and FM Approved
• 450 PSI maximum pressure rating
• Adjustable pneumatic delay (0–90 seconds)
• Dual SPDT contacts rated 10 A @ 125/250 VAC
• Weatherproof NEMA 4 enclosure
• Audible alarm (73 dBA) and visual activation indicator
• Field-replaceable switch and timer assembly

Common Applications:

• Wet-pipe fire sprinkler systems
• Large commercial and industrial buildings
• High-pressure or high-flow fire risers

Specifications:

• Operating Temperature: 32°F to 150°F (0°C to 66°C)
• Flow Sensitivity: 4–10 GPM
• Conduit Openings: Two 1/2″ NPT (one open, one knock-out)
• Weight: ~2.6 lbs

Installation Tip: Mounts on vertical or horizontal pipe. Use adjustable delay to prevent false alarms due to water hammer.