McDonnell & Miller Liquid Flow Switches

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McDonnell & Miller Series FS1 High Sensitivity Liquid Flow Switches

For general-purpose applications where high sensitivity is required and moderate or low flow rates are encountered, such as air conditioning, heating, and hydronic systems, water, fuel oil, some viscous liquids, and oils in process work.

McDonnell & Miller Series FS1

Features:

In-line configuration eliminates the need for a pipe tee
High flow capacity
1/2" NPT
Single pole, double throw snap switch
Switch compartment is completely sealed to protect it from the liquid
Sensitivity adjusting screw makes flow adjustment easy
Optional features:

BSPT threads
Gold plated contacts

Minimum temperature (fluid or ambient): 32°F (0°C)
Maximum temperature: 225°F (107°C)
Maximum operating pressure: 100 psi (7 kg/cm²)

McDonnell & Miller Model FS1-W High Sensitivity Liquid Flow Switches

FS1-W switches are for general-purpose applications where high sensitivity is required and moderate or low flow rates are encountered, such as air conditioning, heating, hydronic systems, water, fuel oil, some viscous liquids, and oils in process work.

McDonnell & Miller Model FS1-W

Features:

In-line configuration eliminates the need for a pipe tee
High flow capacity
1/2" NPT
Single pole, double throw snap switch
Switch compartment is completely sealed to protect it from the liquid
Sensitivity adjusting screw makes flow adjustment easy
Minimum temperature (fluid or ambient): 32°F (0°C)
Maximum temperature: 225°F (107°C)
Maximum operating pressure: 100 psi (7 kg/cm²)

Optional Features:

BSPT threads
Gold-plated contacts

McDonnell & Miller Series FS250 General Purpose Liquid Flow Switches

Series FS250 liquid flow switches provide greater reliability and lower flow sensing capabilities in a general-purpose flow switch. Their universal design serves the widest variety of applications, such as starting or stopping electrically operated equipment such as signal lights, alarms, motors, automatic burners, metering devices, and others. They are an excellent replacement for common flow switches from Johnson/Penn, Potter/Taco, Watts, Hydrolevel, and other manufacturers.

McDonnell & Miller Series FS250

Features:

1″ NPT connection
Two electrical knock-outs allow connection from either end
Sensitivity adjusting screw makes flow adjustment easy
Single pole, double throw snap switch
EPDM o-ring sealed
Four stainless steel paddles included: 1", 2", 3" & 6" (25, 50, 80 & 150mm)
Minimum temperature (fluid or ambient): 32°F (0°C)
Maximum temperature: 227°F (107°C)
Maximum pressure: 160 psi (11.3 kg/cm²)
Model FS251 – NEMA 1 enclosure
Model FS254 – NEMA 4 enclosure

McDonnell & Miller Series FS4-3 General Purpose Liquid Flow Switches

Series FS4-3 switches are ideal for starting or stopping electrically operated equipment such as signal lights, alarms, motors, automatic burners, metering devices, and others. They are an excellent replacement for common flow switches from Johnson/Penn, Potter/Taco, Watts, Hydrolevel, and other manufacturers.

McDonnell & Miller Series FS4-3

Features:

1" NPT
Two electrical knock-outs allow connection from either end
Sensitivity adjusting screw makes flow adjustment easy
Single pole, double throw snap switch
Hardened stainless steel bearings minimize friction
Sealed Monel bellows
Four stainless steel paddles included: 1", 2", 3", and 6" (25, 50, 80, and 150mm)
Minimum temperature (fluid or ambient): 32°F (0°C)
Maximum temperature: 300°F (149°C)
Maximum pressure: 160 psi (11.3 kg/cm²)

Optional Features:

Two SPDT switches to make or break two separate circuits
Materials of construction suitable for corrosive liquids
BSPT threads

McDonnell & Miller Series FS4-3T General Purpose Liquid Flow Switches

Series FS4-3T general-purpose liquid flow switches are ideal for starting or stopping electrically operated equipment such as signal lights, alarms, motors, automatic burners, metering devices, and more.

McDonnell & Miller Series FS4-3T

Features:

In-line configuration eliminates the need for a pipe tee
Sizes available:

3/4" NPT
1" NPT

Paddles available for low, medium, or high flow
Two electrical knock-outs allow connection from either end
Sensitivity adjusting screw makes flow adjustment easy
Single pole, double throw snap switch
Hardened stainless steel bearings minimize friction
Sealed Monel bellows
Minimum temperature (fluid or ambient): 32°F (0°C)
Maximum temperature: 300°F (149°C)
Maximum pressure: 160 psi (11.3 kg/cm²)

McDonnell & Miller Series FS5 General Purpose Liquid Flow Switches

Series FS5 switches are for general-purpose applications requiring low flow rate sensitivity.

McDonnell & Miller Series FS5

Features:

In-line configuration eliminates the need for a pipe tee
Sizes available:

3/4" NPT
1" NPT

Materials of construction

Models FS5 & FS5-D: brass, carbon, and EPDM elastomer (for water)
Models FS5-S & FS5-DS: stainless steel, carbon, and Buna-N (for water or water and petroleum base compounds)

Single pole, double throw snap switch
Sensitivity adjusting screw makes flow adjustment easy
Optional feature: BSPT threads
Minimum temperature (fluid or ambient): 32°F (0°C)
Maximum temperature:

225°F (107°C) – stainless steel models
250°F (121°C) – brass

Maximum operating pressure: 150 psi (10.5 kg/cm²)

McDonnell & Miller Series FS6 High Sensitivity Liquid Flow Switches

Series FS6 switches are ideal for heavy-duty applications requiring high sensitivity, such as water treatment systems, cooling systems for electronic circuits, compressors, booster pumps, and bearings, and other applications that need instant switching.

McDonnell & Miller Series FS6

Features:

In-line configuration eliminates the need for a pipe tee
Very high flow capacity
Actuates at an extremely low flow rate
Sizes available:

3/4" NPT
1" NPT

Single pole, double throw snap switch
Switch compartment is completely sealed to protect it from the liquid
Sensitivity adjusting screw makes flow adjustment easy
Optional feature:

BSPT threads

Minimum temperature (fluid or ambient): 32°F (0°C)
Maximum temperature: 225°F (107°C)
Maximum operating pressure: 100 psi (7 kg/cm²)

McDonnell & Miller Model FS6-W High Sensitivity Liquid Flow Switches

FS6-W switches are for heavy-duty applications with high sensitivity, such as water treatment systems, cooling systems for electronic circuits, compressors, booster pumps, bearings, and other applications that need instant switching.

McDonnell & Miller Model FS6-W

Features:

In-line configuration eliminates the need for a pipe tee
Very high flow capacity
Actuates at an extremely low flow rate
Sizes available:

3/4" NPT
1" NPT

Single pole, double throw snap switch
Switch compartment is completely sealed to protect it from the liquid
Sensitivity adjusting screw makes flow adjustment easy
Minimum temperature (fluid or ambient): 32°F (0°C)
Maximum temperature: 225°F (107°C)
Maximum operating pressure: 100 psi (7 kg/cm²)
BSPT threads are optional

McDonnell & Miller Series FS7-4 Industrial Liquid Flow Switches

Universal design serves the widest variety of large pipe applications, including heating and hydronic systems, air conditioning, refrigeration, and process work.

McDonnell & Miller Series FS7-4

Features:

1-1/4" NPT
Brass with sealed tube construction
Single pole, double throw snap switch
Magnetic switching mechanism eliminates the need for bellows
Sensitivity adjusting screw makes flow adjustment easy
Paddles can be trimmed to suit application needs
Minimum temperature (fluid or ambient): 32°F (0°C)
Maximum temperature: 300°F (149°C)
Maximum operating pressure:

300 psi (21 kg/cm²)
1000 psi (70 kg/cm²) – stainless steel models

Optional Features:

Extended paddle arm – model FS7-4L
Two SPDT switches to make or break two separate circuits
Stainless steel body and paddles
BSPT threads

McDonnell & Miller Series FS7-4E Industrial Liquid Flow Switches

Series FS7-4E switches are for hazardous environment applications requiring a NEMA 7 (Class I, Group C or D) or NEMA 9 Class II, Group E, F, or G) rated flow switch.

McDonnell & Miller Series FS7-4E

Features:

1-1/4" NPT
Brass with sealed tube construction
Single pole, double throw snap switch
Magnetic switching mechanism
Sensitivity adjusting screw makes flow adjustment easy
Paddles can be trimmed to suit application needs
Minimum temperature (fluid or ambient): 32°F (0°C)
Maximum temperature: 300°F (149°C)
- Maximum operating pressure:
- 300 psi (21 kg/cm²)
- 1000 psi (70 kg/cm²) – stainless steel models

Optional features:

Extended paddle arm
Stainless steel body and paddles
BSPT threads

McDonnell & Miller Series FS7-4W Industrial Liquid Flow Switches

1-1/4" NPT Series FS7-4W switches are ideal for applications requiring a water-tight, dust-tight, or NEMA 4X-rated flow switch.

McDonnell & Miller Series FS7-4W

Features:

Brass with sealed tube construction
Single pole, double throw snap switch
Magnetic switching mechanism eliminates need for bellows
Sensitivity adjusting screw makes flow adjustment easy
Paddles can be trimmed to suit application needs
Minimum temperature (fluid or ambient): -65°F (-54°C)
Maximum temperature: 300°F (149°C)
- Maximum operating pressure:
- 300 psi (21 kg/cm²)
- 1000 psi (70 kg/cm²) – stainless steel models

Optional Features:

Extended paddle arm
Stainless steel body and paddles
BSPT threads

McDonnell & Miller Series FS8-W General Purpose Liquid Flow Switches

Series FS8-W liquid flow switches are for general-purpose applications with environmental exposure or require a water-tight, dust-tight, or NEMA 4X rated flow switch 1″ NPT.

McDonnell & Miller Series FS8-W

Features:

Sealed Monel bellows
Single pole, double throw snap switch
Four stainless steel paddles included – 1", 2", 3", and 6" (25, 50, 80, and 150mm)
Sensitivity adjusting screw makes flow adjustment easy
Minimum temperature (fluid or ambient): 32°F (0°C)
Maximum temperature: 225°F (107°C)
Maximum operating pressure: 160 psi (11.3 kg/cm²)
Replacement for NEMA 4X-style flow switches from Potter/Taco, Watts, Penn, and other manufacturers