Compact threaded-type vane waterflow detector with adjustable pneumatic delay (0–90 s), designed for wet-pipe fire-sprinkler systems. Built for accuracy, long service life, and compliance with NFPA 13/25/72 standards.
Overview
The VDRT series waterflow detectors are compact, threaded-type devices that sense water movement in wet-pipe fire-sprinkler systems.
When the flow reaches 10 GPM (≈ 37.8 L/min) or higher, the vane deflects and triggers an electrical alarm output after a preset mechanical delay.
If flow drops below 4 GPM (≈ 15 L/min), the detector resets automatically.
Each unit features a pneumatic delay mechanism (adjustable 0–90 s, factory-set to 20 s), dual SPDT switches, and a directional cover for easy visual inspection.
It is supplied with four paddles for DN25–DN50 threaded tees and a height gauge for proper installation depth.⚠ Use in wet-pipe systems only — not for deluge or pre-action systems.
| Item | Specification |
|---|---|
| Contact Rating | 10 A @ 125/250 VAC ; 3 A @ 24 VDC |
| Flow Sensitivity | 15 – 37.8 L/min (4 – 10 GPM) |
| Working Pressure | 31 bar (450 psi) |
| Operating Temperature | 0 – 68 °C (32 – 155 °F) |
| Shipping Weight | ≈ 1 kg |
| Delay Adjustment | 0 – 90 s (pneumatic, factory set 20 s) |
| Switch Type | Two SPDT switches (COM/B-NO) |
| Mount Type | Threaded tee 1″ NPT branch |
| Nominal Size (mm/in) | Threaded Tee Type | Approx. Depth (in) |
|---|---|---|
| DN25 (1″) | 1 × 1 × 1 | 2 1⁄8 |
| DN32 (1¼″) | 1¼ × 1¼ × 1 | 2 1⁄2 |
| DN40 (1½″) | 1½ × 1½ × 1 | 2 3⁄4 |
| DN50 (2″) | 2 × 2 × 1 | 3 1⁄4 |
