Potter Amseco OSYSU-2 OS&Y Valve Supervisory Switch, 2 SPDT

The Potter Amseco OSYSU-2 is a dual-contact outside screw and yoke (OS&Y) valve supervisory switch with two SPDT Form C contacts and a NEMA 4X/6P weather-resistant enclosure for fire sprinkler systems. Designed to monitor the fully open position of OS&Y gate valves, it detects valve closure and switch removal through an adjustable three-position trip mechanism. The OSYSU-2 accommodates most 2- to 12-inch valves, features 10A contacts rated at 125/250 VAC, and supports indoor or outdoor installation from -40 F to 140 F.

Potter OSYSU-2 Dual-Contact OS&Y Sprinkler Valve Supervisory Switch

The Potter Amseco OSYSU-2 is a dual-contact fire sprinkler valve supervisory switch designed to monitor the open position of outside screw and yoke (OS&Y) gate valves in commercial, industrial, and institutional fire protection systems. Manufactured by Potter Electric Signal Company, the OSYSU-2 incorporates two single-pole, double-throw (SPDT) Form C switch contacts that change state when a monitored sprinkler control valve moves away from its fully open position or when the supervisory assembly is removed from the valve. The device mounts directly to the valve yoke and uses a spring-loaded, adjustable trip rod to monitor movement of the valve stem. It accommodates most OS&Y gate valves ranging from 2 to 12 inches (50 to 300 mm) and can be fitted to certain smaller valves down to 1/2 inch when the installation permits. Its dual-switch configuration supports connection to compatible fire alarm supervisory circuits and additional monitoring equipment, helping identify valve conditions that could compromise sprinkler system water delivery.

The OSYSU-2 features two independent SPDT Form C contacts rated at 10 amps at 125/250 VAC or 2 amps at 30 VDC resistive, with a minimum switching load of 10 mA at 24 VDC. Its mechanical three-position supervisory mechanism detects both valve closure and removal of the switch from the monitored valve. During normal operation, the spring-loaded trip rod rests in a groove on the fully open valve stem, maintaining the contacts in their normal supervisory condition. When the valve handwheel is rotated toward the closed position, the stem moves the trip rod out of its groove and activates the switch contacts. The manufacturer specifies that the switch must operate within the first two revolutions of the valve handwheel when the valve is turned from fully open toward closed. The contacts remain activated as the valve continues closing and return to normal only when the valve is restored to its fully open position. Because the OSYSU-2 is a mechanically operated dry-contact device, it does not require a separate operating power supply; the connected monitoring circuit provides the electrical supervision.

The Potter OSYSU-2 features a NEMA 4X (IP65) and NEMA 6P (IP67) rated enclosure designed for indoor and outdoor fire sprinkler installations. The housing combines a weather-, ultraviolet-, and flame-resistant high-impact composite cover with a die-cast metal base finished in black powder coating. Corrosion-resistant components and an environmental operating range of -40 F to 140 F (-40 C to 60 C) support installation in exposed mechanical rooms, sprinkler riser areas, exterior valve assemblies, and other demanding fire protection environments. The enclosure includes two 1/2-inch conduit knockouts, screw terminals accommodating conductors up to 12 AWG, and tamper-resistant cover screws. A special cover-removal tool is supplied with each device to restrict unauthorized access to the internal switch mechanism. The manufacturer's adjustable-length trip rod, knurled mounting bracket, visual switch-position indicators, and micro-adjustment feature facilitate positioning and alignment without repeatedly removing the mounting assembly. For locations requiring additional corrosion protection of the external mounting hardware, Potter offers the separately designated OSYSU-2 CRH configuration.

The Potter OSYSU-2 is designed for automatic fire sprinkler systems requiring supervisory monitoring of OS&Y control valves, including commercial buildings, warehouses, manufacturing facilities, schools, hospitals, and other properties protected by wet-pipe or compatible sprinkler systems. Its two Form C contact sets permit separate connections for fire alarm supervision and compatible auxiliary monitoring applications, subject to the electrical ratings and applicable installation requirements. The switch is identified by Potter as cULus Listed, FM Approved, and CE marked, with service applications referenced under NFPA 13, NFPA 13D, NFPA 13R, and NFPA 72. Manufacturer instructions require testing the switch and its associated monitoring circuit after installation and during periodic system inspections, with Potter recommending quarterly testing or more frequent inspection when required by the authority having jurisdiction. Unlike the OSYSU-1, which provides one SPDT contact set, the OSYSU-2 provides two independent contact sets for expanded supervisory signaling flexibility. Its rugged environmental enclosure, adjustable valve-stem actuator, tamper-resistant construction, and dual-contact switching make the OSYSU-2 a practical solution for monitoring sprinkler control valve position and maintaining fire protection system supervision.