The York D4120 Duct Smoke Detector is a photoelectric sensing device designed to detect smoke in HVAC duct systems and shut down air handling units to prevent the spread of smoke through the ductwork. This unit combines reliable detection technology with easy installation and maintenance, making it ideal for commercial and industrial air handling applications. Key Features: Genuine York OEM duct smoke detector for HVAC systems. Photoelectric sensing technology ensures accurate smoke detection with minimal false alarms. Rugged housing protects components from dust and air turbulence in duct environments. Equipped with transparent cover for easy visual inspection. Works with a wide range of HVAC control and monitoring systems. Optional accessories available (sampling tubes, relay modules, etc.). Specifications: Part Number: D4120 Type: Photoelectric duct smoke detector Voltage: 24 VAC/DC or 120/240 VAC (depending on configuration) Air Velocity Range: 100?4,000 ft/min Operating Temperature: 32F?131F (0C?55C) Housing: Rugged plastic with clear cover Mounting: Duct mount Manufacturer: York Compatible Models: AY018MA322, 2HG04700124, B3HP042A25, D1NQ036D05606, D2HE048A46EB, D3CG072N09925, D7CG048N06058EC, DF036N08N2AAA1, D1NH048N09006, D2NP048N11006NX, and more. Why Choose This Item: The York D4120 Duct Smoke Detector provides early, accurate detection of smoke in HVAC air handling systems, helping to ensure occupant safety and system protection. Its photoelectric technology, durable construction, and compatibility with York equipment make it a reliable and essential component for any building?s safety system.