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Flow Switches
When fluid movement falls outside set thresholds, flow switches trigger alarms or shutdowns that protect pumps, heaters, and cooling systems from costly damage. Mechanical, thermal, and ultrasonic models support insertion and inline installation in pipes of every size.
Filters 122 Results
122 items
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The Dwyer - FS-100-050 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 0.5 GPM Switch Point, 50 VA SPST, 3/4 ", NPT Female, ± 10 % Accuracy, PP, and 12 " (300mm) Wire L. Part of the FS-100 Series. Sold individually.
$114.77
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-160 is a Flow Switch featuring Paddle, Heavy Duty, Liquid, 4 GPM to 500 GPM, 15 A SPDT, 1 ", NPT Male, ± 1 % Accuracy, 316 SS, 304 SS, Brass, and EPDM. Sold individually.
$254.33
Should ship between 03 Nov and 06 Nov
Subject to factory lead times
The Dwyer - FST-321-SPST is a Flow Switch featuring Thermal Dispersion, Gas, 1 FPS to 90 FPS, 1 A SPST Relay, N.O/N.C, Selectable, 3/4 " to 1-1/2 ", NPT Male, ± 5 % Accuracy, PP, PVDF, and 10 ' Wire L. Part of the FST-320 Series. Sold individually.
$359.23
Should ship between 06 Dec and 13 Dec
Subject to factory lead times
The Dwyer - FSW301 is a Flow Switch featuring Low Cost, Economical, Liquid, 4 GPM to 132 GPM, 26 VA SPST, 1/2 ", NPT Male, Brass, SS, PP, and Noryl. Part of the FSW300 Series. Sold individually.
$371.78
Should ship between 03 Nov and 06 Nov
Subject to factory lead times
The Dwyer - FST-212-SPST is a Flow Switch featuring Thermal Dispersion, Liquid, 0.04 FPS to 3 FPS, 1 A SPST Relay, N.O/N.C, Selectable, 3/4 " to 1-1/2 ", NPT Male, ± 5 % Accuracy, PVDF, and 10 " Wire L. Part of the FST-200 Series. Sold individually.
$564.90
Should ship between 06 Dec and 13 Dec
Subject to factory lead times
The Dwyer - FS-100-025 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 0.25 GPM Switch Point, 50 VA SPST, 3/4 ", NPT Female, ± 10 % Accuracy, PP, and 12 " (300mm) Wire L. Part of the FS-100 Series. Sold individually.
$108.64
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-25 is a Flow Switch featuring Trim-to-Size, Paddle, Liquid, 43 Centistokes, SPDT, 1 ", PT, ± 1 % Accuracy, 304 SS, and Aluminum. Sold individually.
$448.77
Should ship between 03 Nov and 06 Nov
Subject to factory lead times
The Dwyer - FST-221-SPST is a Flow Switch featuring Thermal Dispersion, Liquid, 0.04 FPS to 3 FPS, 1 A SPST Relay, N.O/N.C, Selectable, 2 " to 12 ", NPT Male, ± 5 % Accuracy, PP, PVDF, and 10 " Wire L. Part of the FST-200 Series. Sold individually.
$340.79
Should ship between 06 Dec and 13 Dec
Subject to factory lead times
The Dwyer - FSW-42A is a Flow Switch for 3 " to 10 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW-40A Series. Sold individually.
$742.53
Should ship between 03 Nov and 06 Nov
Subject to factory lead times
The Dwyer - FSW304 is a Flow Switch featuring Low Cost, Economical, Liquid, 3.5 GPM to 4.4 GPM, 26 VA SPST, 1 ", NPT Female, and Brass. Part of the FSW300 Series. Sold individually.
$428.69
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-41A is a Flow Switch for 1-1/2 " to 2-1/2 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW-40A Series. Sold individually.
$742.53
Should ship between 03 Nov and 06 Nov
Subject to factory lead times
The Dwyer - FST-211-SPST is a Flow Switch featuring Thermal Dispersion, Liquid, 0.04 FPS to 3 FPS, 1 A SPST Relay, N.O/N.C, Selectable, 3/4 " to 1-1/2 ", NPT Male, ± 5 % Accuracy, PP, PVDF, and 10 " Wire L. Part of the FST-200 Series. Sold individually.
$325.52
Should ship between 06 Dec and 13 Dec
Subject to factory lead times
The Dwyer - FSW-30A is a Flow Switch featuring Non-Magnetic, Industrial, Water, 0.12 GPM to 8 GPM, 15 A SPDT, 1/2 ", NPT Female, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW30 Series. Sold individually.
$851.89
Should ship between 03 Nov and 06 Nov
Subject to factory lead times
The Dwyer - FST1001R is a Flow Switch featuring Economical, Air, 0 FPM to 5000 FPM, 2 SPST N.O Relays, 1/4 ", Compression Fitting, ± 2 % Accuracy, 304 SS, 12 " Wire L, and Remote Probe. Part of the FST1000 Series. Sold individually.
Save 8%$622.77
$572.15
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FS-100-250 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 2.5 GPM Switch Point, 50 VA SPST, 3/4 ", NPT Female, ± 10 % Accuracy, PP, and 12 " (300mm) Wire L. Part of the FS-100 Series. Sold individually.
$114.77
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-43A is a Flow Switch for 10 " to 48 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW-40A Series. Sold individually.
$742.53
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FS-100-200 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 2 GPM Switch Point, 50 VA SPST, 3/4 ", NPT Female, ± 10 % Accuracy, PP, and 12 " (300mm) Wire L. Part of the FS-100 Series. Sold individually.
$108.64
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FST1001A is a Flow Switch featuring Economical, Air, 0 FPM to 5000 FPM, 2 SPST N.O Relays, 1/4 ", Compression Fitting, ± 2 % Accuracy, 304 SS, 12 " Wire L, and Fixed Probe. Part of the FST1000 Series. Sold individually.
Save 8%$547.28
$502.80
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FS-100-100 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 1 GPM Switch Point, 50 VA SPST, 3/4 ", NPT Female, ± 10 % Accuracy, PP, and 12 " (300mm) Wire L. Part of the FS-100 Series. Sold individually.
$108.64
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-42A-SS is a Flow Switch for 3 " to 10 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, EPDM, FKM, and PTFE. Part of the FSW-40A Series. Sold individually.
$1,174.96
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-6212 is a Flow Switch featuring Thermal Dispersion, Liquid 0.09 FPS to 9.84 FPS, Gas 0.16 FPS to 49 FPS, 5 A SPDT, 3/4 ", NPT Male, ± 10 % Accuracy, 316 SS, and 2 " Insertion L. Part of the FSW-6000 Series. Sold individually.
$1,170.78
Should ship between 29 Nov and 06 Dec
Subject to factory lead times
The Dwyer - FSW303 is a Flow Switch featuring Low Cost, Economical, Liquid, 1.8 GPM to 2.4 GPM, 26 VA SPST, 3/4 ", NPT Female, and Brass. Part of the FSW300 Series. Sold individually.
$428.69
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-40A is a Flow Switch for 1 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW-40A Series. Sold individually.
$702.86
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW302 is a Flow Switch featuring Low Cost, Economical, Liquid, 0.9 GPM to 1.1 GPM, 26 VA SPST, 1/2 ", NPT Female, and Brass. Part of the FSW300 Series. Sold individually.
$428.69
Should ship between 22 Nov and 06 Dec
Subject to factory lead times
The Dwyer - FS-100-050 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 0.5 GPM Switch Point, 50 VA SPST, 3/4 ", NPT Female, ± 10 % Accuracy, PP, and 12 " (300mm) Wire L. Part of the FS-100 Series. Sold individually.
$114.77
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-160 is a Flow Switch featuring Paddle, Heavy Duty, Liquid, 4 GPM to 500 GPM, 15 A SPDT, 1 ", NPT Male, ± 1 % Accuracy, 316 SS, 304 SS, Brass, and EPDM. Sold individually.
$254.33
Should ship between 03 Nov and 06 Nov
Subject to factory lead times
The Dwyer - FST-321-SPST is a Flow Switch featuring Thermal Dispersion, Gas, 1 FPS to 90 FPS, 1 A SPST Relay, N.O/N.C, Selectable, 3/4 " to 1-1/2 ", NPT Male, ± 5 % Accuracy, PP, PVDF, and 10 ' Wire L. Part of the FST-320 Series. Sold individually.
$359.23
Should ship between 06 Dec and 13 Dec
Subject to factory lead times
The Dwyer - FSW301 is a Flow Switch featuring Low Cost, Economical, Liquid, 4 GPM to 132 GPM, 26 VA SPST, 1/2 ", NPT Male, Brass, SS, PP, and Noryl. Part of the FSW300 Series. Sold individually.
$371.78
Should ship between 03 Nov and 06 Nov
Subject to factory lead times
The Dwyer - FST-212-SPST is a Flow Switch featuring Thermal Dispersion, Liquid, 0.04 FPS to 3 FPS, 1 A SPST Relay, N.O/N.C, Selectable, 3/4 " to 1-1/2 ", NPT Male, ± 5 % Accuracy, PVDF, and 10 " Wire L. Part of the FST-200 Series. Sold individually.
$564.90
Should ship between 06 Dec and 13 Dec
Subject to factory lead times
The Dwyer - FS-100-025 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 0.25 GPM Switch Point, 50 VA SPST, 3/4 ", NPT Female, ± 10 % Accuracy, PP, and 12 " (300mm) Wire L. Part of the FS-100 Series. Sold individually.
$108.64
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-25 is a Flow Switch featuring Trim-to-Size, Paddle, Liquid, 43 Centistokes, SPDT, 1 ", PT, ± 1 % Accuracy, 304 SS, and Aluminum. Sold individually.
$448.77
Should ship between 03 Nov and 06 Nov
Subject to factory lead times
The Dwyer - FST-221-SPST is a Flow Switch featuring Thermal Dispersion, Liquid, 0.04 FPS to 3 FPS, 1 A SPST Relay, N.O/N.C, Selectable, 2 " to 12 ", NPT Male, ± 5 % Accuracy, PP, PVDF, and 10 " Wire L. Part of the FST-200 Series. Sold individually.
$340.79
Should ship between 06 Dec and 13 Dec
Subject to factory lead times
The Dwyer - FSW-42A is a Flow Switch for 3 " to 10 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW-40A Series. Sold individually.
$742.53
Should ship between 03 Nov and 06 Nov
Subject to factory lead times
The Dwyer - FSW304 is a Flow Switch featuring Low Cost, Economical, Liquid, 3.5 GPM to 4.4 GPM, 26 VA SPST, 1 ", NPT Female, and Brass. Part of the FSW300 Series. Sold individually.
$428.69
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-41A is a Flow Switch for 1-1/2 " to 2-1/2 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW-40A Series. Sold individually.
$742.53
Should ship between 03 Nov and 06 Nov
Subject to factory lead times
The Dwyer - FST-211-SPST is a Flow Switch featuring Thermal Dispersion, Liquid, 0.04 FPS to 3 FPS, 1 A SPST Relay, N.O/N.C, Selectable, 3/4 " to 1-1/2 ", NPT Male, ± 5 % Accuracy, PP, PVDF, and 10 " Wire L. Part of the FST-200 Series. Sold individually.
$325.52
Should ship between 06 Dec and 13 Dec
Subject to factory lead times
The Dwyer - FSW-30A is a Flow Switch featuring Non-Magnetic, Industrial, Water, 0.12 GPM to 8 GPM, 15 A SPDT, 1/2 ", NPT Female, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW30 Series. Sold individually.
$851.89
Should ship between 03 Nov and 06 Nov
Subject to factory lead times
The Dwyer - FST1001R is a Flow Switch featuring Economical, Air, 0 FPM to 5000 FPM, 2 SPST N.O Relays, 1/4 ", Compression Fitting, ± 2 % Accuracy, 304 SS, 12 " Wire L, and Remote Probe. Part of the FST1000 Series. Sold individually.
Save 8%$622.77
$572.15
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FS-100-250 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 2.5 GPM Switch Point, 50 VA SPST, 3/4 ", NPT Female, ± 10 % Accuracy, PP, and 12 " (300mm) Wire L. Part of the FS-100 Series. Sold individually.
$114.77
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-43A is a Flow Switch for 10 " to 48 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW-40A Series. Sold individually.
$742.53
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FS-100-200 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 2 GPM Switch Point, 50 VA SPST, 3/4 ", NPT Female, ± 10 % Accuracy, PP, and 12 " (300mm) Wire L. Part of the FS-100 Series. Sold individually.
$108.64
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FST1001A is a Flow Switch featuring Economical, Air, 0 FPM to 5000 FPM, 2 SPST N.O Relays, 1/4 ", Compression Fitting, ± 2 % Accuracy, 304 SS, 12 " Wire L, and Fixed Probe. Part of the FST1000 Series. Sold individually.
Save 8%$547.28
$502.80
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FS-100-100 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 1 GPM Switch Point, 50 VA SPST, 3/4 ", NPT Female, ± 10 % Accuracy, PP, and 12 " (300mm) Wire L. Part of the FS-100 Series. Sold individually.
$108.64
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-42A-SS is a Flow Switch for 3 " to 10 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, EPDM, FKM, and PTFE. Part of the FSW-40A Series. Sold individually.
$1,174.96
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-6212 is a Flow Switch featuring Thermal Dispersion, Liquid 0.09 FPS to 9.84 FPS, Gas 0.16 FPS to 49 FPS, 5 A SPDT, 3/4 ", NPT Male, ± 10 % Accuracy, 316 SS, and 2 " Insertion L. Part of the FSW-6000 Series. Sold individually.
$1,170.78
Should ship between 29 Nov and 06 Dec
Subject to factory lead times
The Dwyer - FSW303 is a Flow Switch featuring Low Cost, Economical, Liquid, 1.8 GPM to 2.4 GPM, 26 VA SPST, 3/4 ", NPT Female, and Brass. Part of the FSW300 Series. Sold individually.
$428.69
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW-40A is a Flow Switch for 1 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW-40A Series. Sold individually.
$702.86
Should ship between 15 Nov and 22 Nov
Subject to factory lead times
The Dwyer - FSW302 is a Flow Switch featuring Low Cost, Economical, Liquid, 0.9 GPM to 1.1 GPM, 26 VA SPST, 1/2 ", NPT Female, and Brass. Part of the FSW300 Series. Sold individually.
$428.69
Should ship between 22 Nov and 06 Dec
Subject to factory lead times
FAQ
- A flow switch is a simple device that closes (or opens) a contact when flow crosses a setpoint. It doesn't tell you how much flow there is, just whether flow is present or absent. Used for low-flow shutdowns on pumps and chillers, leak detection, and as a permissive in safety interlocks. Cheap and reliable when all you need is on/off confirmation.
- Paddle switches have a small paddle in the stream that swings against a spring; flow pushes the paddle, a magnet triggers a reed switch. Thermal dispersion switches use a heated probe and detect flow by the cooling effect on it. Piston switches use a piston in a tube that moves with flow against a spring. Shuttle switches use a free shuttle that lifts when flow picks up. Paddle is the workhorse for general use, thermal handles clean low-flow gas or liquid, and piston or shuttle types are for tight, clean service.
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About NISCO Inc.
NISCO offers a wide range of pressure gauges & instruments, diaphragm seals, thermometers, valves, and flow control products to the industrial and commercial marketplaces, as well as other resellers like ourselves. We can also provide other value-added services such as gauge repair, NIST traceable calibration, diaphragm seal assembly, and valve automation. NISCO takes pride in providing extensive product knowledge, helpful customer service, and market competitive pricing to help fit whatever need you may have because it is our goal to be regarded by our customers as the best supplier of pressure, temperature, and flow control products.