4 Inch Vane Type Waterflow Alarm Switch with Retard, Wet Sprinkler Systems VSR-4

The VSR-4 is a vane type waterflow alarm switch designed for wet sprinkler systems. This UL Listed, FM Approved, and LPCB Approved device detects water flow and triggers an alarm signal, making it essential for fire suppression system monitoring and compliance. It features two single pole, double throw snap action switches housed in a tamper-resistant die-cast enclosure.

The VSR-4 activates when flow reaches 10 GPM (38 LPM) or greater downstream of the device. An adjustable, instantly recycling pneumatic retard allows you to set the delay period needed before the alarm triggers, helping reduce false alarms from temporary pressure fluctuations. The switch compartments are isolated for use with dissimilar voltages, and two conduit knockouts support standard 1/2 inch conduit connections.

UL Listed for schedules 5–40 steel pipe in 2–6 inch sizes, with FM and LPC approval for schedules 10–40 in 2–8 inch sizes. Also suitable for sectional waterflow detection on large systems. The die-cast housing features two tamper-resistant screws requiring a special key, with an optional field-installable cover tamper switch available.

• Vane type waterflow switch triggers alarm at 10 GPM (38 LPM) flow rate for automatic system detection
• Two SPDT snap action switches support dissimilar voltages in isolated compartments
• Adjustable pneumatic retard with easy-to-read delay knob reduces false alarms from transient pressure changes
• UL, CUL, CSFM Listed and FM Approved for steel pipe schedules 5–40 in sizes 2–6 inches
• Tamper-resistant die-cast housing with optional field-installable cover tamper switch
• 5-year limited warranty covers defects in materials and workmanship