2.09 [Water Flow Detector WFDTN] [UL, FM] 1 LR.png 2.09 [Water Flow Detector WFDTN] [UL, FM] 3 LR.png 2.09 [Water Flow Detector WFDTN] [UL, FM] 2 LR.png

WFDTN Water Flow Detector

  • FM Approved Logo Mid Grey 300.jpg
  • UL Logo Mid Grey.jpg
Pressure Rating 25.85 Bar (375 PSI)
Working Temperature 0°C to 60°C (32°F to 150°F)
Contact Ratings Two sets of SPDT (Form C)
10.0 A, ½ HP @ 125/250 VAC
2.5 A @ 6/12/24 VDC​
Pipe Size 25mm (1") NPT
Conduit Entrances Two openings for 15mm (½") conduit
Cover Tamper Switch Optional for UL models
Compatible Tee Fittings 25mm (1"), 32mm (1¼"), 40mm (1½"), 50mm (2") ferrous and brass threaded tees
25mm (1"), 32mm (1¼"), 40mm (1½"), 50mm (2"), copper sweat tees;
1in. CPVC tees​​​​
Enclosure Rating NEMA 4 – suitable for indoor/outdoor use
Maximum Surge 5.5 metres per second (18 ft/s)
Triggering Threshold 15.1-37.9 LPM (3.3-8.3 GPM) (4-10 US GPM)
Time Delay Adjustable 0 to 90 seconds
Approvals FM Approved, UL Listed

The WFDTN Series waterflow detectors from System Sensor consists of a rugged, NEMA 4-rated enclosure that is more damage resistant than previous metal designs. The waterflow detector is designed for both indoor and outdoor use, with the widest available temperature range, from 32°F to 150°F.

Both the WFDTN with incorporated timer and WFDTNRN with immediate activation fit any tee that has a 1 in. NPT branch, including: 1in., 1¼in., 1½ in. and 2in. NPT threaded ferrous and brass tees; 1in., 1¼in., 1½in. and 2in. copper tees, CPVC tees. Twelve different clearly marked plastic paddles are available to fit different installation configurations.

UL-listed models are equipped with tamper-resistant cover screws to prevent unauthorized entry. Inside, two sets of SPDT (Form C) synchronized switches are enclosed in a durable terminal block with new layout designed to make wiring easy with wire ready terminals, COM terminals are on a different elevation, large barrier between switches and easy to read raised textured lettering all make wiring easy. An optional cover tamper switch is available, securely snaps into place, no tools required.

The WFDTN incorporates a mechanical time delay feature, which minimizes the risk of false alarm due to pressure surges or air trapped in the fire sprinkler system. The larger and easy to turn timer dial makes setting the waterflow detector easy with high contrast pad printed markings. The dial offers three tabs to help with turning, with one larger tab located on the dial position for approximately 60 seconds, a notch is also indicated on the dial to locate approximately 30 seconds making setting the detector in dimmly lit locations easy.

The WFDTN series is designed for accuracy and repeatability. The detector also offers improved performance during vibration in riser applications where detectors are exposed to a large in rush of water.


Ferrous and brass threaded tees Copper Sweat Tees CPVC Tees
(1") (1") (1")
(1 1/4") (1 1/4") -
(1 1/2") (1 1/2") -
(2") (2") -