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MCDONNELL & MILLER Flow Switch: Paddle, 1 in For Pipe Size, 1 in NPT, 1 in Connection Size - Insertion-Style Switches for Liquids
McDonnell & MillerInsertion-Style Switches for Liquids

MCDONNELL & MILLER Flow Switch: Paddle, 1 in For Pipe Size, 1 in NPT, 1 in Connection Size

The MCDONNELL & MILLER FS4-3 is a paddle-type insertion-style flow switch for liquids, designed for 1-inch pipe sizes with a 1-inch NPT connection. It features a contact rating of 44.4 A at 120V (locked rotor) for AC…

SKU 3G-OTH-93463

Also listed as: FS43 · FS4 3

Brand
McDonnell & Miller
Item
Flow Switch: Paddle, 1 in For Pipe Size, 1 in NPT, 1 in Connection Size
Category
Insertion-Style Switches for Liquids
Available to Order
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Delivery
Worldwide DHL shipping from Singapore; 7–14 business days door-to-door for most destinations.
Payment
Invoicing in USD. Bank transfer (SWIFT) and corporate PO accepted.

Technical Specifications

McDonnell & Miller
Manufacturer Part Number
FS4-3
Type
NPT
NPT
1 in
For Pipe Size
1 in
Connection Size
1 in
Contact Rating (AC)
44.4 A @ 120V (Locked Rotor)

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

Product Description

The MCDONNELL & MILLER FS4-3 is a paddle-type insertion-style flow switch for liquids, designed for 1-inch pipe sizes with a 1-inch NPT connection. It features a contact rating of 44.4 A at 120V (locked rotor) for AC applications.

Frequently Asked Questions

What is the MCDONNELL & MILLER FS4-3 flow switch used for?

The MCDONNELL & MILLER FS4-3 is a paddle-type insertion-style flow switch for liquids. It detects flow or no-flow conditions in 1-inch pipes, commonly used in HVAC, boiler, and industrial water systems to protect pumps and equipment.

What are the specifications of the MCDONNELL & MILLER FS4-3?

The FS4-3 is a paddle flow switch for 1-inch pipe size with a 1-inch NPT connection. Its AC contact rating is 44.4 A at 120V (locked rotor). The manufacturer part number is FS4-3, and it is designed for liquid applications.

Where to buy the MCDONNELL & MILLER FS4-3 worldwide?

3G Electric supplies the MCDONNELL & MILLER FS4-3 flow switch worldwide. As a global industrial distributor, we handle full logistics, customs clearance, and delivery to your location. Contact us for availability and lead time.

How to install the MCDONNELL & MILLER FS4-3 flow switch?

Install the FS4-3 in a horizontal pipe section with the paddle oriented correctly for flow direction. Ensure the 1-inch NPT connection is sealed properly. Follow standard electrical safety practices for the 120V AC circuit. Consult the manufacturer's manual for torque and wiring 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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