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Mcdonnell & Miller Series AF3 Air Flow Switches
Mcdonnell & MillerFlow Switches

Mcdonnell & Miller Series AF3 Air Flow Switches

Note: listed by manufacturer as obsolete/discontinued.

SKU 3G-OTH-02750

Brand
Mcdonnell & Miller
Item
Series AF3 Air Flow Switches
Category
Flow Switches
Available to Order
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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 Documents

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

Product Description

Note: listed by manufacturer as obsolete/discontinued.

Frequently Asked Questions

What is the McDonnell & Miller AF3 flow switch used for?

The McDonnell & Miller AF3 is a general-purpose low-velocity flow switch designed for applications where an economical switch is needed. It is commonly used in HVAC, water treatment, and industrial piping systems to detect flow or no-flow conditions in ducts or pipes of 8 inches (203 mm) minimum size.

What are the specifications of the McDonnell & Miller AF3 flow switch?

The AF3 flow switch features a paddle that fits a minimum duct size of 8 inches (203 mm). It is designed for low-velocity applications and includes two electrical connections. Note that the manufacturer lists this model as obsolete or discontinued, so availability may be limited.

Where to buy the McDonnell & Miller AF3 flow switch in Singapore?

You can source the McDonnell & Miller AF3 flow switch through 3G Electric in Singapore. We handle logistics, customs clearance, and delivery to your facility. Contact us for current pricing and lead time, as this model is listed as discontinued by the manufacturer.

How to install the McDonnell & Miller AF3 flow switch?

Install the AF3 flow switch in a horizontal pipe section with the paddle oriented correctly for flow direction. Ensure the minimum duct size of 8 inches (203 mm) is met. Follow standard wiring practices for the two electrical connections and verify proper operation after installation. Consult the manufacturer's manual for specific torque and clearance requirements.

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 flow switches. We supply genuine products with in-stock availability on common SKUs, technical documentation, commissioning support, and warranty service — worldwide.

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Compatible alternatives & equivalents

Cross-referenced by specification & description
For general purpose applications with medium and high velocity requirements Paddle fits 8 (203mm) minimum duct size, or 6 (152mm) if trimmed Brass
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For general purpose applications with medium and high velocity requirements Paddle fits 8 (203mm) minimum duct size, or 6 (152mm) if trimmed Brass
In-line configuration eliminates need for a pipe tee Sizes available 3 4 NPT 1 NPT Paddles available for low, medium or high flow Two electrical
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In-line configuration eliminates need for a pipe tee Sizes available 3 4 NPT 1 NPT Paddles available for low, medium or high flow Two electrical
Paddle-type flow switch for liquid systems, installed inline in 1-inch pipes with a 1-inch BSP connection. Rated 7.4 A at 120V AC full load. Used to detect liquid flow in piping systems for process control or alarm activation
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Paddle-type flow switch for liquid systems, installed inline in 1-inch pipes with a 1-inch BSP connection. Rated 7.4 A at 120V AC full load. Used to detect liquid flow in piping systems for process control or alarm activation
Paddle-type flow switch for liquids, installed inline in 1-inch pipe systems. Detects flow or no-flow conditions for pump protection, boiler low-water cutoff, and cooling water monitoring. Features 1-inch NPT connection and AC contact rating of 3.7 A at 240V full load
McDonnell & Miller
Paddle-type flow switch for liquids, installed inline in 1-inch pipe systems. Detects flow or no-flow conditions for pump protection, boiler low-water cutoff, and cooling water monitoring. Features 1-inch NPT connection and AC contact rating of 3.7 A at 240V full load
1 NPT Two electrical knock-outs allows connection from either end Sensitivity adjusting screw makes flow adjustment easy Single pole, double throw snap
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1 NPT Two electrical knock-outs allows connection from either end Sensitivity adjusting screw makes flow adjustment easy Single pole, double throw snap
This inline flow switch uses a paddle to detect liquid flow in 1-inch pipe systems. It features a 1-inch NPT connection and an AC contact rating of 22.2 A at 240V (locked rotor). Typical applications include pump protection, boiler low-water cutoff, and cooling water monitoring
McDonnell & Miller
This inline flow switch uses a paddle to detect liquid flow in 1-inch pipe systems. It features a 1-inch NPT connection and an AC contact rating of 22.2 A at 240V (locked rotor). Typical applications include pump protection, boiler low-water cutoff, and cooling water monitoring

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