McDonnell & Miller FS251 SPDT Liquid Flow Switch 1" NPT with Multiple Paddle Sizes

The McDonnell & Miller FS251 is a general-purpose liquid flow switch designed for reliable flow detection in commercial and industrial HVAC systems, boilers, and process applications. This rugged flow switch features a single-pole double-throw (SPDT) contact configuration and a 1-inch NPT threaded connection for straightforward installation in standard pipe systems.

Key Features:

• SPDT (Single Pole Double Throw) contact configuration for flexible control applications
• 1-inch NPT threaded connection for secure mounting in piping systems
• Includes four stainless steel paddle sizes: 1", 2", 3", and 6" to accommodate various pipe sizes and flow rates
• Stainless steel paddle construction resists corrosion and ensures long service life
• General-purpose design suitable for water, glycol solutions, and compatible liquids
• Adjustable flow rate setpoint for customized activation threshold
• Proven McDonnell & Miller reliability for critical flow monitoring applications

The FS251 is ideal for freeze protection systems, pump proving, cooling tower monitoring, and other applications requiring dependable flow detection. The multiple paddle sizes allow for optimal sensitivity across a wide range of pipe diameters and flow conditions, making this switch versatile for various installation requirements.