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MCDONNELL & MILLER Flow Switch: Paddle, 1 1/4 in/16 in For Pipe Size, Brass - Insertion-Style Switches for Liquids
McDonnell & MillerInsertion-Style Switches for Liquids

MCDONNELL & MILLER Flow Switch: Paddle, 1 1/4 in/16 in For Pipe Size, Brass

The MCDONNELL & MILLER FS7-4W is a paddle-type insertion-style flow switch for liquids, designed for pipe sizes from 1-1/4 in to 16 in. It features a brass body with a 1-1/4 in NPT connection and an SPDT switch rated…

SKU 3G-OTH-93930

Also listed as: FS74W · FS7 4W

Brand
McDonnell & Miller
Item
Flow Switch: Paddle, 1 1/4 in/16 in For Pipe Size, Brass
Category
Insertion-Style Switches for Liquids
Available to Order
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Local availability & support

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
FS7-4W
Type
1 1/4 in/16 in For Pipe Size, Brass, NPT, SPDT
NPT
1 1/4 in
For Pipe Size
1-1/4 in
Contact Rating (AC)
7.4 A @ 120V (Full Load)
Hazardous Location Rating
Class I, Div 1 and 2, Group C, D

Technical Documents

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

Product Description

The MCDONNELL & MILLER FS7-4W is a paddle-type insertion-style flow switch for liquids, designed for pipe sizes from 1-1/4 in to 16 in. It features a brass body with a 1-1/4 in NPT connection and an SPDT switch rated at 7.4 A @ 120V (Full Load). This switch carries a hazardous location rating of Class I, Div 1 and 2, Group C, D.

Frequently Asked Questions

What is the McDonnell & Miller FS7-4W flow switch used for?

The McDonnell & Miller FS7-4W is a paddle-type insertion flow switch for liquids. It detects flow or no-flow conditions in pipes from 1-1/4 in to 16 in, commonly used in industrial process control, HVAC, and water treatment systems to protect pumps and equipment.

What are the specifications of the McDonnell & Miller FS7-4W?

The FS7-4W has a brass body with a 1-1/4 in NPT connection, SPDT switch rated at 7.4 A @ 120V (Full Load), and a hazardous location rating of Class I, Div 1 and 2, Group C, D. It fits pipe sizes from 1-1/4 in to 16 in.

Where to buy the McDonnell & Miller FS7-4W worldwide?

3G Electric supplies the McDonnell & Miller FS7-4W flow switch worldwide. As a global industrial solutions provider, we handle full logistics, customs clearance, and delivery to your site. Contact us for pricing and lead time on this item.

How to install a McDonnell & Miller paddle flow switch?

Install the FS7-4W in a horizontal pipe section with the paddle oriented against flow direction. Ensure the pipe is fully drained and the NPT connection is sealed with thread tape. Wire the SPDT switch per your control circuit, typically for pump start/stop or alarm.

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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