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MCDONNELL & MILLER General Purpose Switch: Paddle, 1 in/6 in For Pipe Size - Insertion-Style Switches for Liquids
McDonnell & MillerInsertion-Style Switches for Liquids

MCDONNELL & MILLER General Purpose Switch: Paddle, 1 in/6 in For Pipe Size

The McDonnell & Miller FS251 is a general-purpose, insertion-style paddle switch for liquids, designed for use with a 6-inch pipe size. It features a brass body with a 1-inch NPT connection and an AC contact rating…

SKU 3G-OTH-93528

Brand
McDonnell & Miller
Item
General Purpose Switch: Paddle, 1 in/6 in For Pipe Size
Category
Insertion-Style Switches for Liquids
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Technical Specifications

McDonnell & Miller
Manufacturer Part Number
FS251
Type
1 in/6 in For Pipe Size, Brass, NPT
NPT
1 in
For Pipe Size
6 in
Contact Rating (AC)
44.4 A @ 120V (Locked Rotor)
View Full Spec Sheet

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McDonnell & Miller Products
3G Electric (S) Pte. Ltd. — Singapore

Product Description

The McDonnell & Miller FS251 is a general-purpose, insertion-style paddle switch for liquids, designed for use with a 6-inch pipe size. It features a brass body with a 1-inch NPT connection and an AC contact rating of 44.4 A at 120V (locked rotor). This switch is suitable for liquid level detection in industrial applications.

Frequently Asked Questions

What is the McDonnell & Miller FS251 used for?

The McDonnell & Miller FS251 is an insertion-style paddle switch for liquid level detection in industrial piping systems. It is designed for 6-inch pipe sizes and triggers an electrical signal when liquid flow or level changes, commonly used in HVAC, boiler, and process control applications.

What are the specifications of the McDonnell & Miller FS251?

The FS251 has a brass body with a 1-inch NPT connection, fits 6-inch pipe, and carries a locked-rotor AC contact rating of 44.4 A at 120V. It is a general-purpose paddle switch for liquids, manufactured by McDonnell & Miller under MPN FS251.

Where to buy the McDonnell & Miller FS251 worldwide?

3G Electric supplies the McDonnell & Miller FS251 worldwide. As a global industrial distributor, we handle full logistics, customs clearance, and delivery to your site. Contact us for availability and lead time; we source and deliver this insertion-style switch to any country.

How to install the McDonnell & Miller FS251 paddle switch?

Install the FS251 by threading the 1-inch NPT brass body into a compatible fitting on a 6-inch pipe. Ensure the paddle is oriented correctly for flow direction. Follow standard electrical safety practices for wiring the 44.4 A contact rating. Consult the manufacturer's manual for torque and positioning details.

Used in

Common applications for McDonnell & Miller
Steam boiler low-water cutoff — McDonnell & Miller inline flow switches (e.g., FS-1) for automatic burner shutdown
Cooling water flow monitoring — McDonnell & Miller insertion-style switches (e.g., FS4-3D) in large-diameter pipes
Hazardous-area process lines — McDonnell & Miller FS7-4E with NEMA 7/9 enclosure for Class I, Div 1 locations
HVAC chilled water systems — McDonnell & Miller FS6-1 inline switch for pump flow verification
Industrial wastewater treatment — McDonnell & Miller FS4-3S stainless steel switch for corrosive fluid flow detection
Boiler feedwater control — McDonnell & Miller FS8-WJ with BSP connections for international installations

McDonnell & Miller Products

3G Electric supplies McDonnell & Miller insertion-style switches for liquids. We supply genuine products with in-stock availability on common SKUs, technical documentation, commissioning support, and warranty service — worldwide.

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