Potter Amseco VSR-2-1/2 Vane Waterflow Alarm Switch

The Potter Amseco VSR-21 2 is a 2-1/2-inch vane-type waterflow alarm switch with adjustable pneumatic retard, designed to detect sustained water movement in wet-pipe fire sprinkler systems. Featuring two independent SPDT Form C contacts, a 4-10 GPM flow sensitivity range, and a field-adjustable 0-90-second retard, it provides alarm signaling while reducing nuisance activations caused by temporary pressure surges. The switch supports 450 PSI maximum service pressure and is UL Listed for 2-1/2-inch Schedule 5-40 steel pipe, with FM approval for Schedule 10-40 installations. Its NEMA 4/IP54 weather-resistant enclosure supports indoor and outdoor applications.

Potter Amseco VSR-21 2 Vane-Type Waterflow Alarm Switch with Retard for 2-1/2-Inch Sprinkler Pipe

The Potter Amseco VSR-21 2 Waterflow Alarm Switch provides automatic detection of sprinkler water movement in 2-1/2-inch (DN65 nominal) wet-pipe fire protection systems. Manufactured by Potter Electric Signal Company, the device uses a paddle-type sensing mechanism to detect waterflow and activate electrical alarm contacts after the selected retard interval. The VSR-21 2 incorporates two independent SPDT snap-action switches and an adjustable pneumatic retard assembly, allowing integration with compatible fire alarm control panels, central station monitoring equipment, and local notification devices. The unit is UL Listed for 2-1/2-inch Schedule 5-40 steel pipe and FM Approved for Schedule 10-40 steel pipe. Typical applications include commercial sprinkler risers, sectional waterflow monitoring, warehouses, institutional facilities, and other buildings equipped with wet-pipe sprinkler systems.

The VSR-21 2 features a UL-listed waterflow sensitivity range of 4-10 gallons per minute (15-38 LPM), with Potter specifying a minimum 10 GPM flow for operational testing. Its adjustable pneumatic retard provides a delay of approximately 0-90 seconds, helping prevent unwanted alarms from momentary water surges, trapped air, and pressure fluctuations. The retard automatically resets when waterflow stops before the selected delay expires. The switch is rated for 450 PSI (31 bar) maximum service pressure and water surge velocities up to 18 feet per second (5.5 m/s). A factory-installed non-corrosive sleeve protects the saddle opening, while the replaceable vane and retard/switch assembly support maintenance. The retard/switch assembly can be serviced without removing the complete device from the sprinkler piping.

The Potter VSR-21 2 includes two independent Form C (SPDT) electrical contacts, each providing normally open, normally closed, and common terminal connections. The contacts are rated at 10A at 125/250 VAC or 2A at 30 VDC resistive, with a minimum switching current of 10 mA at 24 VDC. One contact set can initiate a waterflow alarm through a compatible supervised fire alarm circuit, while the second can operate a separately powered audible or visual notification appliance. The enclosure incorporates two 1/2-inch conduit knockouts and separate switch wiring compartments for circuits operating at different voltages. Its weather-, UV-, and flame-resistant composite cover and die-cast aluminum base provide durable protection for the internal switches and retard mechanism. An optional VSRCTSK cover tamper switch kit, Potter stock number 0090148, allows supervision of unauthorized cover removal.

The VSR-21 2 mounts to nominal 2-1/2-inch steel sprinkler pipe with a 2.875-inch (73 mm) outside diameter using its saddle and U-bolt mounting assembly. Potter specifies a pipe opening measuring 1-1/4 inches with a tolerance of +1/8 inch/-1/16 inch, with the vane positioned in the direction of waterflow. The device supports horizontal or vertical installation; on horizontal pipe, it must be mounted on the upper side. Installation requires at least 6 inches of separation from fittings that change waterflow direction and 24 inches from valves or drains. Its NEMA 4/IP54-rated enclosure supports indoor and outdoor use with appropriate conduit fittings, within an operating temperature range of 40 F to 120 F (4.5 C to 49 C). The VSR-21 2 carries applicable UL, cUL, FM, and LPCB approvals and supports sprinkler monitoring installations governed by NFPA 13, NFPA 13D, NFPA 13R, and NFPA 72. Installation and operational testing must follow Potter's instructions and the requirements of the authority having jurisdiction.