Johnson Controls AFS-460-DSS Sensing Switch

For contractors managing airflow verification in sensitive HVAC systems, the Johnson Controls AFS-460-DSS Sensing Switch provides the redundancy and manual intervention required for critical safety protocols. This industrial-grade air pressure sensing switch is designed to monitor positive, negative, or differential air pressure within a range of 1.25" ± 0.06" to 12" w.c. Featuring two SPST normally closed contact arrangements, this dual-switch configuration allows for separate control and alarm functions within a single housing. The integrated manual reset button ensures that once a set point is reached, the system remains locked out until a technician performs a visual inspection, preventing hazardous recycling of equipment. Built with a durable plated housing and a silicone diaphragm, the AFS-460-DSS handles a maximum pressure of 0.5 psi and connects via a standard 1/4" OD sample line connection using an integral compression ferrule and nut. This unit is essential for proving fan status, monitoring filter blockage, and ensuring proper duct static pressure in commercial energy management applications.

• Redundant Safety Logic: Dual SPST-NC contacts allow one switch to act as a primary controller while the second triggers a remote alarm or safety lockout.
• Field-Adjustable Set Points: The progressive differential can be fine-tuned from 1.25" to 12" w.c. using the set point adjusting screw located under the protective enclosure cover.
• Robust Environmental Tolerance: Operates reliably in temperatures ranging from -40°F to 180°F, making it suitable for both intake and exhaust monitoring in varied climates.
• Versatile Sampling: Accepts rigid or semi-rigid 1/4" OD tubing for flexible installation in positive, negative, or differential pressure applications.
• Code Compliance: UL-approved design with a 7/8" diameter opening to accommodate standard 1/2" conduit connections.

How do I plumb the AFS-460-DSS for differential pressure?
Connect the higher pressure (or the source of positive pressure) to Inlet H and the lower pressure (or negative source) to Inlet L. Always mount the unit with the diaphragm in a vertical plane to ensure the most accurate low-end set point calibration.

What is the purpose of the manual reset on this model?
The manual reset is a safety feature that prevents the switch from automatically re-closing after a pressure drop or rise. It requires a technician to physically depress the button on the enclosure cover to restore the circuit, ensuring the cause of the trip is addressed.

Can this switch be used with combustion products?
Yes, it is designed for use with air or combustion by-products that do not degrade silicone, making it a viable option for burner airflow proving or flue gas monitoring.

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.