The Johnson Controls AFS-405 is a professional-grade adjustable differential air pressure switch designed for precision monitoring in HVAC, DDC, and energy management systems. Engineered with a glass-filled polycarbonate housing and a high-performance silicone diaphragm, this sensing switch is optimized for detecting positive, negative, or differential pressure between 0.05 and 12.0 inches water column. The inclusion of gold-plated contacts ensures high conductivity and reliable signal switching in low-current dry circuit applications, making it a critical component for proving fan status or monitoring filter pressure drop. With a SPDT contact arrangement and 1/4-inch OD sample line connections, the AFS-405 air pressure switch provides the versatility required for complex air-handling unit (AHU) configurations where consistent air flow proving is mandatory for system safety and performance. Key Benefits Field-Adjustable Performance: Features a wide operating range of 0.07" to 12.0" WC, allowing technicians to calibrate the trip point precisely using a digital manometer. Enhanced Reliability: Gold contacts prevent oxidation in low-voltage circuits, ensuring the proving switch maintains signal integrity over its 100,000-cycle life. Flexible Installation: Designed for surface mounting in any vertical plane, accepting 1/4" OD rigid or semi-rigid tubing with integral compression ferrules. Robust Protection: A zinc-plated steel enclosure cover shields SPDT screw terminals and the adjustment screw from accidental contact or debris. Common Questions How do I calibrate the set point for specific duct static pressure requirements? To adjust the AFS-405, rotate the adjustment screw clockwise to increase the set point or counter-clockwise to decrease it. For precision, always utilize a digital manometer to verify the actual "Operate" and "Release" pressures during commissioning. What media is compatible with this pressure switch? This switch is rated for air and combustion by-products that do not degrade silicone. It is ideal for general HVAC air handling but should be verified against specific corrosive exhaust gases in industrial settings. Can I use flexible plastic tubing with the compression fittings? The standard connectors are designed for 1/4" OD rigid tubing. For flexible plastic tubing applications, a slip-on tubing adapter (Part Number 18311) is recommended to ensure a leak-free seal. Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
