McDonnell & Miller FS1 1/2" In-Line High Sensitivity Flow Switch

The McDonnell & Miller FS1 is a high-sensitivity in-line flow switch designed for reliable flow detection in hydronic heating, cooling, and process control systems. This precision instrument monitors liquid flow and provides electrical switching when flow rates meet or fall below the setpoint threshold.

Key Features:

• 1/2" NPT threaded connection for easy installation in standard piping systems
• High sensitivity paddle design detects low flow rates with minimal pressure drop
• Single pole double throw (SPDT) switch contact for versatile control applications
• Durable brass body construction for corrosion resistance and long service life
• Adjustable flow setpoint allows customization for specific system requirements
• Suitable for water, water-glycol solutions, and other compatible liquids
• UL recognized component for safety and reliability

The FS1 flow switch is commonly used to protect pumps, boilers, chillers, and heat exchangers by ensuring adequate flow before equipment startup or triggering alarms during low-flow conditions. Its compact in-line design makes it ideal for installations where space is limited. The high-sensitivity paddle mechanism provides accurate flow detection even at low velocities, making it suitable for systems with variable flow requirements.