Flow Switches

Flow Switches

McDonnell & Miller Flow Switches are equipped with either one or two SPDT switches except for Model FS7-4A (Pneumatic).

Information:

They can make or break an electrical circuit when flow starts or when flow stops, and can be used to:

  • Actuate a signal when flow stops
    • Start a motor with flow, Shut off an alarm when flow is adequate Stop a motor with no flow
  • Size of pipe
    • McDonnell & Miller Flow Switches may be used on pipe sizes 1/2" - 36" NPT.
  • How much flow is present?
    • The flow rate at which the flow switch is to respond should be determined next. McDonnell & Miller Flow Switches are actuated (make or break) with an increase in flow. The term “Flow” represents the actual movement (velocity) of liquid within a pipe sufficient to actuate the switch. The term “No-Flow” represents a decrease in velocity, or total flow stoppage, which will permit the switch to return to its original position. IMPORTANT: In operation, the switch must be actuated by “Flow” before it can be reversed again by “No-Flow”. All McDonnell & Miller Flow Switches can easily be adjusted in the field to require a higher actuating “Flow” or “No-Flow”.
  • Maximum liquid pressure in pipe
    • The maximum pipeline pressure should be considered when selecting a particular model. Different flow switch models can accommodate a range of pipeline pressures up to 1000 psi (70kg/cm2).
  • Maximum temperature
    • Determine the liquid and ambient atmospheric temperature when selecting the flow switch model. Various McDonnell & Miller Flow Switches can be used at ambient temperatures from 32°F (0°C) and liquid temperatures up to 300°F (149°C). If ambient temperatures are lower than 32°F (0°C) use the FS7-4W.
  • Type of liquid
    • McDonnell & Miller Flow Switch models have wetted parts of brass, monel or stainless steel. Depending on the particular model they may be used with water, certain light viscous fluids, some oils, various caustic solutions and other fluids.
  • Atmosphere surrounding flow switch
    • It should be determined if the location will be subject to high humidity, weather conditions or explosive atmospheres. Standard, water tight and hazardous duty flow switch models are available. 

If you have any questions please give us a call at 1-800-781-7405 or email us your request. Sales@NationalPumpSupply.com

  • Product
  • Qty in Cart
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  • 120601 McDonnell & Miller FS8-W - 1" Flow Switch

    120601 McDonnell & Miller FS8-W - 1" Flow Switch

    McDonnell & Miller

    $184.95
    120601 McDonnell & Miller FS8-W - 1" Flow Switch General purpose flow switch w/NEMA 4X enclosure 120601. Mcdonnell & Miller 120601 Instruction Manual For general purpose applications with environmental exposure, or those requiring a...
    $184.95
    Qty in Cart: 0
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    $184.95
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  • 120611 McDonnell & Miller FS251

    120611 McDonnell & Miller FS251 Flow Switch With NEMA 1 Enclosure

    McDonnell & Miller

    $138.95
    McDonnell & Miller FS251 General Purpose Flow Switch With NEMA 1 Enclosure 120611, Replaces FS4-3. Information: McDonnell & Miller FS4 Brochure McDonnell & Miller FS4 Instruction Manual Features Universal design serves the widest...
    $138.95
    Qty in Cart: 0
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    $138.95
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  • 114400 McDonnell & Miller FS4-3 1" Flow Switch 1" NPT

    114400 McDonnell & Miller FS4-3 1" Flow Switch

    McDonnell & Miller

    $134.95
    114400 McDonnell & Miller FS4-3 1" Flow Switch 1" NPT. Click here for more info on Mcdonnell Miller Flow Switches Universal design serves the widest variety of applications. For starting or stopping electrically operated equipment such as signal...
    $134.95
    Qty in Cart: 0
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    $134.95
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  • 120610 McDonnell & Miller FS254 Flow Switch

    120610 McDonnell & Miller FS254 Flow Switch With NEMA 4 Enclosure

    McDonnell & Miller

    $178.95
    120610 McDonnell & Miller FS254 Flow Switch With NEMA 4 Enclosure, Replaces FS8-W. McDonnell & Miller FS254 Brochure Features: Universal design serves the widest variety of applications For starting or stopping electrically operated equipment...
    $178.95
    Qty in Cart: 0
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    $178.95
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  • 113200 McDonnell & Miller FS-1 1/2" Liquid Flow Switch

    113200 McDonnell & Miller FS-1 1/2" Liquid Flow Switch

    McDonnell & Miller

    $214.95
    113200 McDonnell & Miller FS-1 1/2" Liquid Flow Switch. McDonnell & Miller FS1 Instruction Manual Features: For general purpose applications where high sensitivity is required and moderate or low flow rates are encountered such as air...
    $214.95
    Qty in Cart: 0
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    $214.95
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  • 114639 McDonnell & Miller FS4-3RP-T 1" Flow Switch FS4-3 With Test Button

    114639 McDonnell & Miller FS4-3RP-T 1" Flow Switch

    McDonnell & Miller

    $178.95
    114639 McDonnell & Miller FS4-3RP-T 1" Flow Switch FS4-3 With Test Button. McDonnell & Miller FS4 Brochure McDonnell & Miller FS4 Instruction Manual Universal design serves the widest variety of applications. For starting or stopping...
    $178.95
    Qty in Cart: 0
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    $178.95
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  • 123400 McDonnell & Miller Air Flow Switch Model AF3

    123400 McDonnell & Miller AF3 Air Flow Switch

    McDonnell & Miller

    $149.95
    123400 McDonnell & Miller Air Flow Switch Model AF3. McDonnell & Miller AF1 Flow Switch Instruction Manual For general purpose low velocity applications where the most economical flow switch is desired. Paddle fits 8" (203mm) minimum...
    $149.95
    Qty in Cart: 0
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    $149.95
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  • 123000 McDonnell & Miller Air Flow Switch Model AF1-S

    123000 McDonnell & Miller Air Flow Switch AF1-S

    McDonnell & Miller

    $292.95
    123000 McDonnell & Miller Air Flow Switch AF1-S. Mcdonnell & Miller AF1 Flow Switch Instruction Manual For general purpose applications with medium and high velocity requirements: Paddle fits 8" (203mm) minimum duct size, or 6" (152mm) if...
    $292.95
    Qty in Cart: 0
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    $292.95
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  • 114780 McDonnell & Miller FS5-1 - 1" Flow Switch

    114780 McDonnell & Miller FS5-1 - 1" Flow Switch

    McDonnell & Miller

    $224.95
    114780 McDonnell & Miller FS5-1 - 1" Flow Switch 114780. McDonnell & Miller FS5 Instruction Manual Features: In-line configuration eliminates need for a pipe tee Sizes available: 3/4" NPT, 1" NPT Materials of construction: Brass, carbon &...
    $224.95
    Qty in Cart: 0
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    $224.95
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  • 114760 McDonnell & Miller FS5-3/4 - 3/4" Flow Switch

    114760 McDonnell & Miller FS5-3/4 - 3/4" Flow Switch

    McDonnell & Miller

    $224.95
    114760 McDonnell & Miller FS5-3/4 - 3/4" Flow Switch 114760. Information: McDonnell & Miller FS5 Instruction Manual Features: For general purpose applications requiring low flow rate sensitivity In-line configuration eliminates need for a pipe...
    $224.95
    Qty in Cart: 0
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    $224.95
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  • 119700 McDonnell & Miller FS7-4 - 1-1/4" Flow Switch

    119700 McDonnell & Miller FS7-4 - 1-1/4" Flow Switch

    McDonnell & Miller

    $359.95
    119700 McDonnell & Miller FS7-4 - 1-1/4" Flow Switch Paddle Style. McDonnell & Miller FS7 Overview McDonnell & Miller FS7 Instruction Manual Features: Universal design serves the widest variety of large pipe applications, including heating...
    $359.95
    Qty in Cart: 0
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    $359.95
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  • 114900 McDonnell & Miller FS4-3T2-3/4 - 3/4" Flow Switch

    114900 McDonnell & Miller FS4-3T2-3/4 - 3/4" Flow Switch

    McDonnell & Miller

    $214.95
    114900 McDonnell & Miller FS4-3T2-3/4 - 3/4" Flow Switch With NPT Body Medium Flow Rate 114900. McDonnell & Miller FS4 Instruction Manual Features: For starting or stopping electrically operated equipment such as signal lights, alarms, motors,...
    $214.95
    Qty in Cart: 0
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    $214.95
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  • 115400 McDonnell & Miller FS6-3/4 - 3/4" Flow Switch

    McDonnell & Miller

    $334.95
    115400 McDonnell & Miller FS6-3/4 - 3/4" Flow Switch-High Sensitivity. McDonnell & Miller FS6 Instruction Manual This Mcdonnell & Miller flow swicth is for heavy duty applications where high sensitivity is required, such as water treatment...
    $334.95
    Qty in Cart: 0
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    $334.95
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  • 120160 McDonnell & Miller FS7-4S - 1-1/4" Flow Switch

    120160 McDonnell & Miller FS7-4S - 1-1/4" Flow Switch

    McDonnell & Miller

    $598.95
    120160 McDonnell & Miller FS7-4S - 1-1/4" Flow Switch With Stainless Steel Body 120160. Mcdonnell & Miller 120160 Instruction Manual Features: Universal design serves the widest variety of large pipe applications, including heating and hydronic...
    $598.95
    Qty in Cart: 0
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    $598.95
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  • 115300 McDonnell & Miller FS4-3T3-1 - 1" Flow Switch

    115300 McDonnell & Miller FS4-3T3-1 - 1" Flow Switch

    McDonnell & Miller

    $214.95
    115300 McDonnell & Miller FS4-3T3-1 - 1" Flow Switch With NPT Body Low Flow Rate 115300. McDonnell & Miller FS4 Instruction Manual Features: For starting or stopping electrically operated equipment such as signal lights, alarms, motors,...
    $214.95
    Qty in Cart: 0
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    $214.95
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  • 123200 McDonnell & Miller Air Flow Switch Model AF2

    123200 McDonnell & Miller AF2 Air Flow Switch Model AF2

    McDonnell & Miller

    $226.95
    123200 McDonnell & Miller Air Flow Switch Model AF2. Mcdonnell & Miller AF1 Flow Switch Instruction Manual For low velocity applications: Paddle fits 8" (203mm) minimum duct size Two electrical knock-outs allow connection from either end...
    $226.95
    Qty in Cart: 0
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    $226.95
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  • 120201 McDonnell & Miller FS7-4W - 1-1/4" Flow Switch

    120201 McDonnell & Miller FS7-4W - 1-1/4" Flow Switch

    McDonnell & Miller

    $444.95
    120201 McDonnell & Miller FS7-4W - 1-1/4" Flow Switch w/NEMA 4X Enclosure 120201. Information: Mcdonnell & Miller 120201 Instruction Manual Features: For applications requiring a water-tight, dust-tight or a NEMA 4X rated flow switch. 1-1/4"...
    $444.95
    Qty in Cart: 0
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    $444.95
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  • 115000 McDonnell & Miller FS4-3T3-3/4 - 3/4" Flow Switch

    115000 McDonnell & Miller FS4-3T3-3/4 - 3/4" Flow Switch

    McDonnell & Miller

    $214.95
    McDonnell & Miller FS4-3T3-3/4 - 3/4" Flow Switch With NPT Body Low Flow Rate 115000. McDonnell & Miller FS4 Instruction Manual Features: For starting or stopping electrically operated equipment such as signal lights, alarms, motors, automatic...
    $214.95
    Qty in Cart: 0
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    $214.95
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  • McDonnell & Miller FS4-3S 1" Flow Switch w/Stainless Steel Body Monel Bellows 114641

    114641 McDonnell & Miller FS4-3S 1" Flow Switch

    McDonnell & Miller

    $414.95
    McDonnell & Miller FS4-3S 1" Flow Switch w/Stainless Steel Body Monel Bellows 114641. McDonnell & Miller FS4 Brochure McDonnell & Miller FS4 Instruction Manual Universal design serves the widest variety of applications. For starting or...
    $414.95
    Qty in Cart: 0
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    $414.95
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  • 115652 McDonnell & Miller FS6-W-1 - 1" Flow Switch

    115652 McDonnell & Miller FS6-W-1 - 1" Flow Switch

    McDonnell & Miller

    $384.95
    115652 McDonnell & Miller FS6-W-1 - 1" Flow Switch With NEMA 4X Enclosure. McDonnell & Miller FS6 Instruction Manual This Mcdonnell & Miller flow swicth is for heavy duty applications where high sensitivity is required, such as water...
    $384.95
    Qty in Cart: 0
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    $384.95
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