SYSTEM SENSOR (WFD20N) 2″ Waterflow Detector, Schedule 10/40

The System Sensor WFD20N is a 2-inch vane-type waterflow detector for wet-pipe sprinkler systems. It fits 2-inch steel pipe, Schedule 7 through 40. When sustained water flow occurs, two synchronized switches signal the fire alarm panel. Therefore, sprinkler activation is reported without extra interface hardware.

Built-In Retard Against False Alarms

Water surges can trip a flow switch falsely. However, the WFD20N uses a sealed mechanical pneumatic retard. The delay is field-adjustable from 0 to 90 seconds and factory preset near 30 seconds. In addition, delays do not accumulate — the timer resets if flow stops.

System Sensor WFD20N Specifications

• Pipe size: 2-inch steel pipe, Schedule 7–40 (1-1/4 in hole)
• Maximum static pressure: 450 psi
• Flow trigger threshold: 4 to 10 GPM; 18 FPS maximum surge
• Contacts: two synchronized SPDT (Form C); 10 A at 125/250 VAC; 2.5 A at 24 VDC
• Operating temperature: 32°F to 150°F, indoor or outdoor
• Enclosure: NEMA 4; two 1/2-inch conduit entrances; up to 12 AWG wire
• Tamper resistance: tamper-resistant cover screws; optional CTS cover tamper switch

Listings include cULus (S739), CSFM 7770-1653:0231, and FM (3051266). For Canadian installations, the ULC model is the WFD20NA. Also note: steel pipe only — never copper. Finally, System Sensor covers the detector with a three-year warranty.

For more information, contact the Life Safety Consultants team at (888) 557-0558, or email us at: sales@lifesafetycom.com