Send a part number, a photo, or a whole BOM — we supply it and stand behind it. Worldwide shipping to 80+ countries.

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 Flow Switch: Paddle (SKU 3G-OTH-93315, MPN FS7-4) is an insertion-style switch for liquids. It is designed for pipe sizes from 1-1/4 in to 16 in, features a brass body with 1-1/4 in NPT…

SKU 3G-OTH-93315

Also listed as: FS74 · FS7 4

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
Trade pricing by quote — replies within 24h
Qty
WhatsApp an engineerMessage via Telegram
No account needed — your quote request goes straight to our engineers. A free account lets you track quotes and re-order faster.
Worldwide Shipping
Air & sea freight
Datasheet on Request
Technical specs
1-Day Quote
Replies within 24h

Local availability & support — Singapore

Local office
20 Woodlands Link #09-05, Singapore 738733
Phone
+65 8878 8355
Delivery
Same-day or next-business-day delivery within Singapore for in-stock items; 7–14 days for factory-order parts from Europe.
Payment
Invoicing in SGD. PayNow, bank transfer, and corporate PO accepted.
Ships to
Singapore

Technical Specifications

McDonnell & Miller
Manufacturer Part Number
FS7-4
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)
44.4 A @ 120V (Locked Rotor)

Technical Documents

No technical documents available for this product.
Request documentation
Not sure this is the right part? Get a recommendation.

Need installation or engineering help?

Installation, commissioning, maintenance plans, system design, and bundled product + service quotes — one team handles the full scope.
Talk to an engineer

Ask a question

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

Product Description

The MCDONNELL & MILLER Flow Switch: Paddle (SKU 3G-OTH-93315, MPN FS7-4) is an insertion-style switch for liquids. It is designed for pipe sizes from 1-1/4 in to 16 in, features a brass body with 1-1/4 in NPT connection, and has a SPDT contact rated at 44.4 A @ 120V (Locked Rotor).

Frequently Asked Questions

What is the MCDONNELL & MILLER FS7-4 flow switch used for?

The MCDONNELL & MILLER FS7-4 is an insertion-style paddle flow switch for liquids. It detects flow or no-flow conditions in pipes from 1-1/4 in to 16 in, commonly used in HVAC, boiler, and industrial water systems to protect pumps and equipment.

What are the specifications of the MCDONNELL & MILLER FS7-4 flow switch?

The FS7-4 has a brass body with a 1-1/4 in NPT connection, SPDT contacts, and a locked-rotor contact rating of 44.4 A @ 120V AC. It fits pipe sizes from 1-1/4 in to 16 in and is manufactured by MCDONNELL & MILLER.

Where to buy the MCDONNELL & MILLER FS7-4 flow switch worldwide?

3G Electric supplies the MCDONNELL & MILLER FS7-4 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 a MCDONNELL & MILLER paddle flow switch?

Install the FS7-4 by inserting the paddle into the pipe through a 1-1/4 in NPT fitting, ensuring the paddle is sized for the pipe diameter. Wire the SPDT contacts per your control circuit. Always follow local codes and the manufacturer's instructions for safe operation.

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.

You might also need

Burners & Combustion Pumps & Compressors Spare Parts All Products

Compatible alternatives & equivalents

Cross-referenced by specification & description
MCDONNELL & MILLER Flow Switch: 1 in For Pipe Size, 1 in NPT, 1 in Connection Size, NPT, SPDT (MPN FS6-1)
McDonnell & Miller
MCDONNELL & MILLER Flow Switch: 1 in For Pipe Size, 1 in NPT, 1 in Connection Size, NPT, SPDT (MPN FS6-1)
MCDONNELL & MILLER Flow Switch: Paddle, 1 in For Pipe Size, 1 in NPT, 1 in Connection Size, NPT (MPN FS4-3)
McDonnell & Miller
MCDONNELL & MILLER Flow Switch: Paddle, 1 in For Pipe Size, 1 in NPT, 1 in Connection Size, NPT (MPN FS4-3)
MCDONNELL & MILLER Flow Switch: 1 in For Pipe Size, 1 in NPT, 1 in Connection Size, NPT, SPDT (MPN FS6-W-1)
McDonnell & Miller
MCDONNELL & MILLER Flow Switch: 1 in For Pipe Size, 1 in NPT, 1 in Connection Size, NPT, SPDT (MPN FS6-W-1)
MCDONNELL & MILLER General Purpose Switch: Paddle, 1 in/6 in For Pipe Size, Brass, 1 in NPT, NPT (MPN FS254)
McDonnell & Miller
MCDONNELL & MILLER General Purpose Switch: Paddle, 1 in/6 in For Pipe Size, Brass, 1 in NPT, NPT (MPN FS254)
MCDONNELL & MILLER Liquid Flow Switch: 3/4 in For Pipe Size, Brass, 3/4 in NPT, NPT, 32°F to 250°F (MPN FS5-3/4)
McDonnell & Miller
MCDONNELL & MILLER Liquid Flow Switch: 3/4 in For Pipe Size, Brass, 3/4 in NPT, NPT, 32°F to 250°F (MPN FS5-3/4)

More from McDonnell & Miller

View all McDonnell & Miller parts
MCDONNELL & MILLER Flow Switch: Paddle, 1 1/4 in/16 in For Pipe Size, Brass, 1 1/4 in NPT, NPT, SPDT (MPN FS7-4W)
McDonnell & Miller
MCDONNELL & MILLER Flow Switch: Paddle, 1 1/4 in/16 in For Pipe Size, Brass, 1 1/4 in NPT, NPT, SPDT (MPN FS7-4W)
MCDONNELL & MILLER Flow Switch: Paddle, 1 1/4 in/16 in For Pipe Size, Brass, 1 1/4 in NPT, NPT, SPDT (MPN FS7-4SW)
McDonnell & Miller
MCDONNELL & MILLER Flow Switch: Paddle, 1 1/4 in/16 in For Pipe Size, Brass, 1 1/4 in NPT, NPT, SPDT (MPN FS7-4SW)
MCDONNELL & MILLER Flow Switch: Paddle, 1 in For Pipe Size, Stainless Steel, 1 in NPT, NPT, SPDT (MPN FS4-3S)
McDonnell & Miller
MCDONNELL & MILLER Flow Switch: Paddle, 1 in For Pipe Size, Stainless Steel, 1 in NPT, NPT, SPDT (MPN FS4-3S)
MCDONNELL & MILLER General Purpose Switch: Paddle, 1 in/6 in For Pipe Size, Brass, 1 in NPT, NPT (MPN FS251)
McDonnell & Miller
MCDONNELL & MILLER General Purpose Switch: Paddle, 1 in/6 in For Pipe Size, Brass, 1 in NPT, NPT (MPN FS251)
MCDONNELL & MILLER Flow Switch: Paddle, 1 1/4 in/16 in For Pipe Size, Brass, 1 1/4 in NPT, NPT, SPDT (MPN FS7-4S)
McDonnell & Miller
MCDONNELL & MILLER Flow Switch: Paddle, 1 1/4 in/16 in For Pipe Size, Brass, 1 1/4 in NPT, NPT, SPDT (MPN FS7-4S)
MCDONNELL & MILLER Flow Switch: Paddle, 1 in For Pipe Size, 1 in NPT, 1 in Connection Size, NPT (MPN FS4-3D)
McDonnell & Miller
MCDONNELL & MILLER Flow Switch: Paddle, 1 in For Pipe Size, 1 in NPT, 1 in Connection Size, NPT (MPN FS4-3D)
MCDONNELL & MILLER Flow Switch: Paddle, 1 1/4 in/16 in For Pipe Size, Brass, 1 1/4 in NPT, NPT, SPDT (MPN FS7-4E)
McDonnell & Miller
MCDONNELL & MILLER Flow Switch: Paddle, 1 1/4 in/16 in For Pipe Size, Brass, 1 1/4 in NPT, NPT, SPDT (MPN FS7-4E)
MCDONNELL & MILLER Flow Switch: Paddle, 1 in For Pipe Size, 1 in NPT, 1 in Connection Size, NPT (MPN FS4-3RP-T)
McDonnell & Miller
MCDONNELL & MILLER Flow Switch: Paddle, 1 in For Pipe Size, 1 in NPT, 1 in Connection Size, NPT (MPN FS4-3RP-T)